Turquoise Energy Ltd. News #60
Victoria BC
Copyright 2013 Craig Carmichael - February 3rd, 2013

www.TurquoiseEnergy.com = www.ElectricCaik.com = www.ElectricHubcap.com = www.ElectricWeel.com = www.MushroomOutboard.com

Features:
* The New Electric Caik Motor
* MnMn Production Battery Designs

Month In Brief (Project Summaries)
- PCBs by laser printer iron-on transfers - Caik Motor - Production MnMn Battery designs - 12 VDC outlet properly wired
In Passing (Miscellaneous topics and editorial comments)
- EV Sales in BC - Electric Ferry (Norway) - Ominous developments & progress as applied to weapons.
Electric Hubcap Motor Systems
* Electric Caik Motor ("Mini Electric Hubcap") is built and runs great. It's about "cake" size!
* PCBs by Laser Toner Transfer: works decently with the right techniques, glossy magazine paper, and practice. (Made Caik motor magnet & temperature sensor board.)
* Assembling the motor
* Magnet Rotor: Magnet Placement Jig, magnet adhesion failures on first run & rebuild.
* Rebuilt rotor, second tests: runs great - I decided it's 0-2000 RPM instead of 0-3000.
* Projected improvements - Proper motor performance testing?
* Motor controllers need a programmable function to prevent motors from over-revving (Caik could hit 5000RPM?)
Planetary Gear Torque Converter & Ultra-Efficient Vehicle Transmission Project
* Put clutch pedal/cable in Sprint car. (Not a big accomplishment for a month.)
Outboard Motors Projects
* Fitting Honda outboard for the new Electric Caik motor: Square shaft & joy couplings, motor mounting.
Turquoise Battery Project
* Toluene: Still seems to improve graphite conductivity.
* Iron: seems to rust at lower pHes.
* Manganese: theory says it's a "cycle forever" negative electrode.
* Production prototype: case - filler cap/airlock - end compaction for electrode briquettes.
* Battery Cell assembly, step by step procedure
* MnMn Battery Cell: Self discharge... pH 13, a bit high?

No Project Reports on: DSSC solar cells, LED Lighting, Pulsejet steel plate cutter, Magnetic Heat Pumping, Magnetic Motion Machine, Large format NiMH batteries - take 3, Mushroom Outboard, CNC Farming Machine, Superinsulated 12VDC Peltier element fridge (finished except for smart solar control... and in use with food).


Newsletters Index/Highlights: http://www.TurquoiseEnergy.com/news/index.html

Construction Manuals and information:
-  Electric Hubcap Motor - Turquoise Motor Controller - 36 Volt Electric Fan-Heater
- Nanocrystalline glaze to enhance Solar Cell performance - Ersatz 'powder coating' home process for protecting/painting metal

Products Catalog:
 - Electric Hubcap Motor Kit
 - Sodium Sulfate - Lead-Acid battery longevity/renewal
 - NiMH Handy Battery Sticks, Dry Cells
 - LED Light Fixtures
Motor Building Workshops

...all at:  http://www.TurquoiseEnergy.com/ (orders: e-mail craig@saers.com)


January in Brief

    The bulk of the month was spent on the new "Mini Electric Hubcap" motor and, mostly later on, on designing and setting up to make a limited production model MnMn battery. The motor is too fat to be a "pancake" motor, but it's about the size of a cake (3 layers?), so that's what I decided to call it. "ElectricCake.com" was taken, so I initially titled it the "Electric Kake" motor. On February 2nd I decided "Electric Caik" looked better (or at least less bad) and changed it.

Sprint Car, ultra efficient transmission

   I set to work on this on the 6th when I made a mounting for the clutch pedal, drilled some holes, and installed the clutch and its cable in the car. Next is mounting the idler pulley in the transmission unit, but I turned to other things and got no more done.

PCBs with 3D Printer? - No Way!

   I tried 3D printing a sample trace with a donut at each end on a single sided PCB, but the PLA plastic simply fell off the copper at a touch. I should have known. No way will it work.

PCBs with laser printer revisited - Caik motor Magnet Sensor board.

   Somewhere on the web I heard that iron-on transfers printed on a laser printer worked better if the sheet was repeatedly printed with the same pattern, thickening the toner on the acetate sheet. Although not optimistic about the probable results, I decided to give this a try.
   After some complaints from the printer, I got a double print and the two passes lined up better than I expected. The ironing went okay (as well as might be expected), and not too much toner stuck to the acetate to prevent me etching the board. But it was no beauty.

   I'd also read some people used glossy magazine paper instead of acetate. One web site finally explained why: you can soak the paper off, so it won't lift any of the toner from the copper board. Aha! Finally I saw the glimmer of potential good results! (And here I thought people were just using it because they were being cheap!) Trying it revealed more details: thin magazine paper transfers the heat to the toner and board better, and there seems to be less smear. On the minus side, you can't see through it to see any spots of toner that haven't transferred.
   I started getting quite decent results this way, although there seemed to be a spot or two on each board that somehow got missed. Some practice may bring perfection, but I bought an etch resist pen to touch up such spots. With an acceptably working system I won't bother mounting the tiny dremmel tool on the giant CNC machine and attempting to router the copper off after all.

   I also tried the etching system of hydrochloric ("muriatic") acid (2 parts by volume) and hydrogen peroxide (drugstore variety, 3%, 3 parts). It works fine, but much more slowly than 'advertised' and only with continual agitation. The author did say he bought the acid and the peroxide at a chemical place, so his peroxide was probably stronger.

   On the 17th I printed and etched a soil moisture switch circuit I had said I'd do for someone for a sprinkler system. No point watering if it's rained. At least, I think it was for him... but perhaps it has a place in the CNC gardening machine.

"Electric Caik" motor

   I spent much of the month on the "Mini Electric Hubcap" motor with a total of 4 or 5 weeks of construction counting December. I completed it and have a fine motor and the molds and jigs to make more of them. I think people will really like the fact that it runs on only 24 volts. It's electrically safe and makes system design simple. Rather than put in too many details here, I'll list the main outline (long enough by itself!) and refer those interested to the detailed report under Electric Hubcap Systems.

Electric Caik, Stator Side
* I fitted the pressed shell bearings to the motor bells on the 5th, using hex bolts and "T" nuts since the intended carriage bolt system was too bulky to fit in at either end. Theoretically the motor could be thinner and slightly smaller diameter, but in practical terms it was as thin and small as I could make it and I almost made the rotor compartment too thin to fit everything. On the rotor bushing I had to drill recesses and use flat head bolts to eliminate the normally protruding hex heads.
* I designed, made and installed the magnet and temperature sensors circuit board (13th?), then wired the coils on the 14th, then painted all the motor rotors I have sitting around ("ersatz powder coating" - TE News #??)
* To put the magnets on the rotors, I made a complete circle HDPE plastic jig with an exact size rectangle space for each magnet, and a rotating lid having just one slot, to uncover one magnet place at a time. That's safest to prevent magnets - fighting with each other (and the worker) magnetically when they're being placed - from snapping together accidentally and perhaps doing damage or injury. (Epoxy glue doesn't stick to polyethylene.) Having every magnet held in position by the jig eliminates having to C-clamp them.
* I tried using OpenSCad and Pronterface to generate the G-code for making the jig, but the whole process got too convoluted. I went back to writing the main sequence using a spreadsheet. But later it occurred to me I might go into the editable Python code of Pronterface and make a version that makes G-code tailored to my CNC drill/router instead of to the 3D printer, for future CNC projects.
* I installed eight 1"x2"x.375" magnets on a rotor. Thanks to CNC precision, this was definitely the most perfectly aligned magnet rotor I've done, and the rotor balance proved very good. Of course now I'll do one of these jigs for the larger motors as well.
* I tested the magnet sensor board. I was glad I did because there were a couple of little problems and I'd have had to open the motor stator (again) to get it to run.
* Using an AD590 temperature chip (or an LM335 chip) is no big expense, and it gives a direct voltmeter reading in degrees Kelvin. (eg, 2.93V=293K. Water freezes at 273ºK. 293-273=20ºC.) A thermistor would essentially require a microcontroller to interpret the temperature reading, so the chip provides a simpler option, albeit in the less common Kelvin scale.
* I wired up the power plug, then milled 2 shaft key slots in the axle - to lock the rotor and for whatever load was put on the outside. (The manual milling machine, still not converted to CNC, does come in handy at times!)
* The (epoxy?) coating on the magnets was so slick they didn't adhere to anything, and when I first ran the motor four of them simply slid out of their pockets and jammed on the outside rim, at no great RPM. And the jammed magnets caused the zinc primer to delaminate and a couple of sections of the strapping ripped up - ouch! (I then pulled all the strapping off by hand - not without effort. The other four magnets were easily knocked off the rotor.)
* I scraped and sanded the rotor down to the steel, sanded the magnets to roughen them up, and re-did the rotor without the zinc primer and polyurethane. (That does unfortunately make it more susceptible to corrosion. Stainless steel would not only be costly -- it's non-magnetic!)

   After completing the second magnet installation, I tried the motor again and ran a few tests. It ran great, smooth and well balanced. I got nervous about turning the RPM up too high and chickened out at 2700 RPM - and at only about 1/4 or 1/3 "throttle". My instinct said it'd be safer to call it a 2000 or at most 2500 RPM motor instead of the planned 3000. I also thought it was using too many watts to turn with no load, but the power needed went down considerably as (presumably) the bearings warmed up. I was then in essence happy with the motor, barring a few ideas for improvements that could wait for another occasion or the next motor. (One idea in particular is to add a microcontroller control to limit such motors to safe RPMs - but that's the domain of the motor controller rather than the motor.)

   The Electric Caik motor project was born (after being a 'theoretical possibility' motor idea for a long time) after a VEVA electric transportation meeting and a subsequent meeting with electric scooter enthusiasts who had attended that in early November. I thought it would be a good size for that, and also for electric marine propulsion. Parts were purchased or ordered in the weeks following that. Creation of molds, jigs and construction commenced some time in December, and it was completed and operational before the end of January. Unlike so many of my long drawn out projects, a new type of motor was developed in under 3 months.

   Next I hope to have proper comprehensive performance testing done by electrical eng. students at Camosun College. Then I'll mount it in the "7.5 HP" Honda outboard shell and try it out on the motorboat, to see how it performs in real life operating conditions. And then probably to see how the "airfoil" shaped propeller performs compared to the "regular" props.
   I avoided the temptation to immediately start in on the outboard or on the bicycle rim motor, in order to focus on batteries - those are what the world seems to need most, and I've had the high energy, "forever" cycle life, permanganate-manganese/moderately alkaline battery chemistry working for nearly a year.
   But on the evening of February 2nd I took the motor out to the outboard, and seeing that it would be quite simple to mount it, I spent a couple of hours on it, and it may be complete in a couple more. The task is simplified by the fact that my 2011 rear motor mounting bracket is usable for the new motor. A boat ride in February seems likely.

Production Battery Design

   All the test battery cells I've made able to open for trying various things and inspection have leaked and become encrusted in salt from the electrolyte around the seams. The leaks cause self-discharge and loss of electrolyte, making any longer period test results questionable at best. On the 20th I decided that, having a proven chemistry, workable materials, and now a plan in my head for what ought to be good, working cells, it was time to put together a production battery design that would be securely glued shut, and a much faster means for producing electrodes - as simple, highly compacted briquettes.
   On the evening of the 21st, I printed the first case, complete with one side face, after a frustrating time unsuccessfully trying to print a separator grille. The next day, I cut the current collectors, and the other side face out of sheet plastic. When the second side is glued on with methylene chloride, heat glue seals the gaps around the electrode terminal protrusions, and a ball bearing covers the filler hole, the cell should be well sealed.
   From the 25th on, I made a selection of improving case designs, separator grilles that became 'baskets' to hold the upper electrode, and a compactor box that compacts 64x64x2mm electrode briquettes from the end instead of the face, requiring only a couple of tons of force instead of 30 or 40. Now that I have custom cases with the 3D printer, it should be actually easier to put together a 'production' cell than a 'test' cell, and it feels like I should have started a while ago. But the ideas had to gel, and I've incorporated an important detail or two that I've learned making test cells in recent months as well as experience with designing 3D printed parts.
   On the 31st I finally had a cell together. When I filled it it started bubbling and I put it on charge immediately to prevent too much oxidation of the zinc. It leaked, and I had quite a time patching it. I've sanded the glue face of the next one much more thoroughly - the top layer of the 3D printing is anything but flat and smooth at smaller scale. It seemed to charge to about 2.4 volts, but wasn't holding that charge too well. pH was probably rather high at around 13. Maybe I should eliminate the calcium hydroxide, as it'll probably hold charge best at pH lower pH, eg, 8 to 11. I ordered some "high range pH tape" paper, pH 6 to 13, to better see what the pH really is. On the other hand, it hasn't had much time yet. It may improve.

   On about the 30th, I decided I simply couldn't let the month pass with no progress at all on the 12VDC house wiring. So I spent a couple of hours and cut a hole in the kitchen wall, installed an electrical box and properly mounted the outlet for the fridge. I thought I'd go with the downstairs theme of brass covers, so I used a square hole "decor" faceplate with a brass (plated!) surround. (Evidently I was using green plastic when I printed all these pieces - they could be any color.) The fit was less than perfect -- the 3D plastic design for the "decor" socket plate seems to need a bit of work.
   I reflect that you could easily fit in 3 or 4 outlets even in this small plate size, instead of just 2. 6 would be easy on a full size cover plate. A switch in place of one could turn some of them off and on. That could eliminate need for a power bar! However, since each socket (and switch) has to be wired up together by the installer, having too many in each plate could make for a lot of extra work. If the CAT standard for 12 VDC outlets and plugs catches on, there'll doubtless be a great variety of pre-wired choices for such things after a while.

12 VDC outlet by the "solar fridge", nearby a 120 VAC outlet
(Ironically, the AC outlet has a 12 VDC power adapter plugged in for the LED globe light that lit the corner for the foto!)


In Passing
Incidental news, editorial opinions

 
BC Electric Vehicle Sales Stats for Dec. 2011 + 2012

   It's not much, but up from near zero for all previous years. It's a start! Someone who would like to buy a lower cost converted car complains that the ones he's seen - an RX7 and two S10 pickup trucks - are all two seaters, unsuitable for his family.

   Also of interest, the first ever 120 car, 360 passenger, 80 meter catamaran electric ferry is said to be going into operation in Norway in 2015. (So far, it looks like it's a computer graphic judging by all the identical cars.)

   The 800KW vessel will charge at each end of the 30 minute route in 10 minutes and save a million litres of diesel fuel per year.

   Since the grid on shore can't provide sufficient power for this rapid charge, the batteries are charged from batteries on shore that are under continuous slower charge. (These are the sort of systems we need, but they will be much more economical when MnMn batteries replace lithium or other types.)




Meandering opinionated write... USA - Switzerland - Weapons & Technology

   I was amused by US president Obama doing what I've always advocated - shortening the work week as an obvious benefit to all the labor saving devices that have been invented in the last century, changing the law to consider that anyone working 30 or more hours a week is working 'full time', down from 35. Unfortunately the intent was merely to make the unemployment stats look less dismal as all the financial fraud sucks the remaining life blood out of the economy, not to actually make anyones' week shorter. If he would shorten the weekly work hours of his bloated civil service to match that figure, he might actually cut a meaningful chunk out of the staggering US deficit, and at the same time (at least theoretically) hire a few of the unemployed if services are to be kept at the same level.

   Instead, he intends to use some of his civil servants to try to confiscate Americans' precious guns nationwide, notwithstanding a decreasing rate of violent crime. If you haven't noticed that the US government has become the most heinous terrorist organization in the world, it's probably because the right to freedom of speech is gone. Journalists and critics are increasingly subject to being harassed, kidnapped and locked away, tortured or killed, and American "mainstream" media is captive and complicit. The persecution of Julian Assange is no isolated case. Get your news off the internet.
   Empowerment against tyrannical government as well as against foreign invasion is the prime purpose of the US constitutional right to bear arms and form defensive militias. (Evidently "guns everywhere" was a bigger factor than the US military in why Japan didn't try to invade Hawaii when they bombed Pearl Harbor.) Many consider Obama's intended violation of that clause to be high treason. He's repeatedly bypassed congress with "executive orders", entering wars in Libya and now Mali (not to mention the less direct attempt to destabilize Syria) when declaring war is supposed to be entirely a prerogative of congress. He's also trying to get rid of 2 term presidency limits, with the obvious intent of making himself "President for Life" Obama. But he is himself a puppet of the corrupt "power brokers".
   There are limits to what people will put up with before they start shooting back or even strapping bombs to their belts. On this continent they haven't been reached since the US civil war, but passions are stirring.
   What Obama is accomplishing is that Americans have purchased 68 million new guns since I started working on electric transportation in 2008, various US states are enacting laws that make enforcing federal laws that violate the US constitution an offense (meaning state agents will arrest federal enforcement agents), and the demand for ammunition is now so high that the police can't buy bullets, which may indicate that people are replenishing supplies for their older weapons as well.
   Could Obama break up the country even in advance of the inevitable US dollar collapse? A small but increasing number are starting to think that civil war is inevitable. Unless he has an epiphany and does an about face, Americans with guns may be the only thing standing in the way of a brutal totalitarian dictatorship. Other countries may soon count themselves thankful if they manage to stay out of it. (If Obama were to do an "about face", he may soon be deposed by those that put him in power -- if not by assassination then perhaps by some public disclosure of hidden 'dirt', such as the "Watergate Scandal" that deposed Nixon... after he had suddenly turned around and ended the 'profitable' Vietnam war, gave China long overdue diplomatic recognition, and started nuclear arms limitation talks with the Russians)

   There is much criticism, eg here in Canada where gun ownership is presently relatively controlled, about the US 'right to bear arms', when we hear in the news about all the murders and accidents with guns there. But in past times lots of Canadians had guns - only hand guns were regulated, and our murder and accident rates were low. My dad, a respected university professor, had a .22 rifle and a couple of shotguns, and used to go duck or game bird hunting with friends (including the Superintendent of Edmonton Schools) on weekends up into the mid 1960's. (They taste much better than any poultry from a store, but I hated plucking them.) He let me shoot the .22 rifle at targets when I got older. And we might want to consider another respected country where everyone has guns: In Switzerland, all men are supposed to keep a military assault rifle locked up at home, and are army trained in using them. Accidents and murders with guns are historically rare in Switzerland.
   Switzerland can raise an army of a million trained men in 24 hours any time the need should arise. This policy has stood Switzerland in good stead. The last occasion was when Hitler began his rampage of Europe. The Swiss said: "If you attack us, we'll fight to the last man and blow every bridge and tunnel." Hitler asked that a plan be prepared for invading Switzerland. Of course mountainous terrain isn't good blitzkrieg country, and his generals reported that it would take 12 divisions 6 months. At no time did Hitler have such forces to spare for so long for such a puny prize. How many Swiss lives were saved as little Switzerland, surrounded by the tide of death of Nazism and Fascism, held out because it was resolute, geographically fortunate... and also armed to the teeth? The deterrent proved sufficient.

   Technological advance making small scale manufacturing ever easier may be making the whole gun control discussion irrelevant. There's evidently a 3D plastic printable gun design on the web, and magnetic coil guns (eg, see youtube, 'rail guns') that can also be made at home use electricity instead of gunpowder to accelerate a steel 'bullet' (most any piece of steel rod or ball bearing) to bullet speeds. None of these simple designs require anything but common parts used for many other things. The magnetic gun doesn't even require recognizable bullets. Then there are powerful lasers, IEDs and other more novel weapons. Soon no one will be able to assume their intended victim doesn't have an effective loaded weapon hidden away somewhere. That could be some deterrent to violence. And nations may more and more easily produce devastating weapons when and as they feel threatened by other nations. Iran's own new advanced stealthy jet fighter is probably a good example of this. (The USA should consider that with all the enemies it's making by its drone strikes, that soon drones may be flying the other way and killing Americans on their own soil.)

   But seeing all this struggle and concern from a materialistic viewpoint retards growth of the soul, and will leave us with many additional lessons to learn when we arrive on the next world of our long upward ascent towards Paradise. It is still true that "Violence begets violence." and "He who lives by the sword dies by the sword."
   We may anticipate that the financial collapse and violence of today and in the immediate forecast will spur vital social changes, that sustainable cultural advances and social justice in the coming century or two will make violence as a dispute resolution technique obsolete and having weapons superfluous, for all future time and for all people. Then, except of course in wilderness areas, people will gladly dispose of their guns over a generation or two, in and because of the absence of any coersion, asking themselves "Why do I have this old thing cluttering up my closet?"

Electric Hubcap Motor Systems

   All the subheadings here this month are about the "Mini Electric Hubcap Motor", now titled the Electric Caik Motor ("ElectricCake.com" was taken). It continues - and essentially concludes - the motor development story started in December, including the making of the molds and jigs to produce the motors, and the making and initial testing of the first one, which runs great.
   Where the Electric Hubcap has 9 coils and 12 supermagnets on a 10" rotor, the Caik is a "2/3 version" with 6 of the same coils and 8 magnets on a 7.5" rotor. The outside diameter is thus smaller (9.25"). The supply voltage is 24 instead of 36, at the same 0-127 amps. If desired it could be wired as 36 volts and 0-82 amps instead by wiring the old style coils, ie, 63 turns of #14 wire instead of 21 turns of #11, with the 2 coils of each phase in parallel instead of in series.

   It runs great, and the rotor is the best balanced one I've made, thanks to the new magnet placement jig below. I had thought that if the regular Electric Hubcap was 0 to 2000 RPM with a 10" magnet rotor, the new one should be about 0 to 3000 RPM with a 7.5" rotor, but as I increased the speed, despite running smoothly the energy seemed so ominous that I stopped at 2700 RPM and headed down again, and decided that maybe it should be rated 0 to 2000 RPM as well, or not a lot more. The back EMF (Kv) seemed quite low at 5.1 mV/RPM and it attained those RPMs with quite low control settings. This would be partly because I used thinner supermagnets, .375" instead of .5", in spite of the fact that the flux gap is probably down to 10 or 11 mm instead of 14 to 16. I think that if I turned it right up with the 24 volt supply and no load, the motor speed would increase until it self destructed, even if that didn't happen until 5000 or more RPM. I'm starting to think that a microcontroller overseeing operation is really a necessity if only to set an RPM limit at a safe maximum regardless of flux gap and load.

   I fitted the pressed shell bearings (received on the 4th) to the motor bells on the 5th. Skipping ahead in the story, there wasn't enough room between the coils in the stator, nor width in the rotor compartment, to use the manufacturer's intended bolting system at either end. Instead I put in some "T" nuts that took up little space inside and tightened short hex head bolts on from the outside.
   On the rotor side I found it necessary to file the hole in the rotor a little so the "H" taper lock bushing slid in 1/4" farther, and then to drill the "H" bolt holes with bevels and use flat head bolts, in order to fit the rotor and bushing into the space without anything hitting anything. Theoretically the rotor compartment just needs to be wide enough internally for the rotor, magnets, and a little air space on each side, about an inch. But with the practicalities of securely mounting the rotor, it just made it in the 1.5".

   (The bearings I ordered came the wrong size, 1" instead of 7/8", but it finally occurred to me the simple answer was simply to make a few mini motors with 1" shafts. Also these bearings might fit more compactly on the rotor end of the larger motors than the trailer bearings, and could potentially shrink the length of the motors by 1/4" or more.) But the first motor has 7/8" bearings and shaft.

Coil Coating

   Some time early in the month I took the coils - the six for this motor and a bunch more - and coated them with ilmenite, using the ilmenite frosted "Plasti-Dip" primer technique described in an earlier TE News.

Coils were painted with Plasti-Dip that contained ilmenite,
and then shaken up in a jar of ilmenite powder, so the powder coated the wet paint.


I decided to do enough coils for the next several motors.
(These are still the coils wound with old surplus magnet wire with cloth
insulation, except the more compact one at the lower left has modern wire.)

PCBs with 3D Printer? - Nope!

   I've put off trying to make more PCBs for quite a while. Now I really needed to design and make some for the Mini Electric Hubcap motor magnet sensors, so I finally turned to the task.

   I tried printing a sample trace with a donut at each end on a single sided PCB with the 3D printer. In addition to the traces not starting smoothly, after the board cooled the PLA plastic simply fell off the copper at a touch. I figure it would never make it through the etchant bath intact no matter how carefully it was handled.

PCBs with laser printer -- with improved techniques, glossy paper, and practice, it works well enough for small single sided boards that aren't too fine.

   Sometime I heard that iron-on transfers printed on a laser printer worked better if the sheet was repeatedly printed with the same pattern, thickening the toner on the acetate sheet. Although not optimistic about the probable results, I decided to give this a try, with the LED constant current board I designed last summer.
   After some complaints from the printer, I got a double print and the two passes lined up better than I expected. The ironing went okay (as well as expected), and not too much toner stuck to the acetate instead of the board.
   I looked up a web site. I'd seen some where glossy paper was used instead of acetate. There was no explanation for this, so I figured the users were just being cheap or it was more convenient. But this site finally explained why: you can soak the paper off, so it won't lift any of the toner from the copper board. Aha! Now I saw the glimmer of why some people claim to get decent results! I didn't want to run old magazine pages through my color laser printer, but on the evening of the 12th some "glossy photo printer paper" meant for inkjets didn't work right in the laser printer, and I tried thin magazine paper, adjustment set to "darkest". I thought it would surely crumple up and jam somewhere in the printer, but it printed well. It also has the valuable attribute of being thin, so the heat of the iron transfers through to the toner and to the copper rapidly. Its one big minus, compared to the acetate, is that you can't see through it. You have to get good results across the board without seeing those results in any detail until it's too late to fix anything that's not well stuck down.

   The next morning (13th) I tried transferring the print to a PCB. First I cleaned the copper, first with scotchbrite, then with toothpaste and a toothbrush per the brilliant cleaning instruction in "How to Electroplate a Penny". Nothing like starting with a clean PCB!
   Then I heated up the board with the iron. When I put the paper on it, it was already starting to stick down. Then I applied the flat of the iron for a minute or so and went back and forth a bit. After soaking it, I pulled the paper off - not in one intact piece. There was lots of fiber left between traces, which I gently rubbed off with my fingers.
   The first attempt looked very good except rough or missing spots out at both "wings" of the board. Evidently the iron, used on the flat, hadn't touched at those edges. Probably the board was slightly curled. So I tried again, and tried hard to get the tip of the iron everywhere. This time it was quite good except one long trace at the top edge was broken in 4 places, and two pads looked like they might be touching. I suspect the iron tip only hit some points on the broken line. There was a bit of smear in one area, and I had noticed the paper move when I'd pulled too hard with the iron. Evidently this is a process one gains proficiency with through experience. (Acetate seems to smear worse.)
   I scraped between the pads and put some 'invisible' tape along the missing path. (It etched off so I just ran a wire.) For next time - and the other board - I decided to get an "Etch Resist Pen" and touch up any small trouble spots by hand. (It didn't work very well, at least not with the etchant I used.)

   I also tried out the HCl (2 parts) + H2O2 (3 parts) etching chemical mix as detailed on the same site. "In seconds your board will be etched." Mine took about 600 seconds, and the next time was longer. Perhaps he had stronger H2O2.

   On one web site, someone said Avery 8.5" x 11" adhesive label backing sheets work fabulous and the toner comes off so cleanly that you can reuse the sheet. But he must have had some really old ones - the more modern ones I have have the backing sheet cut into diagonal strips, no doubt for easier removal.
   So I cast the idea aside. But later it occurred to me that maybe the backing paper for the Mac-Tac I used on the fridge would work the same! I'll try that some time soon.

   By night I had the board drilled, populated and mounted in the motor. There's sure not much room for it in those little motors! I used #8 x 1/2" sheet metal screws into the PP-epoxy composite to hold the board on. Naturally they poked through into the rotor compartment, and (contrary to plan) I wasn't sure they were quite out of the path of the magnets, but they do miss by 1/4" or so.

Magnet & temperature sensor board in the motor
(I used 3 cloth insulated coils and 3 with modern wire -
I couldn't fit the PC board wires between the bulkier cloth insulated coils.)

Magnet Rotor



Rotor magnet placement jig


Caik Magnet Rotor (1st edition)
(2nd build [not shown] was straight on the steel with no paint)

   After installing the circuit board (13th), then wiring the coils (14th), then painting all the motor rotors I have sitting around ("ersatz powder coating" - TE News #??), it came time to put the magnets on the rotor. I made a complete plastic jig of UHMW-PE with an exact size spot for each magnet, and a rotating lid having just one slot to uncover one magnet place at a time. That's safest to prevent magnets - fighting with each other magnetically when they're being placed - from coming together accidentally and perhaps doing damage or injury. The epoxy to glue down the magnets doesn't stick to the polyethylene.
   On the 17th I put together the G-code sequence to router out this jig, and did a dry run by evening. I tried using OpenSCad and Pronterface to generate the G-code from a source file, but the whole process got too convoluted. I went back to writing the main sequence using a spreadsheet with "G01 X" __ "Y" __ - the G-code syntax and line numbers in the spreadsheet boxes as well as the trigonomically calculated co-ordinate values. That at least makes for a fairly simple copy and paste operation.
   Later it occurred to me I might go into the editable Python code of Pronterface and make a version that makes G-code tailored to my CNC drill router instead of to the 3D printer. That could solve future project operations.

   The next day, not without a few hitches, I cut the jig on the CNC router, cut a lid for it, and installed eight 1"x2"x.375" magnets on a rotor. The cut & paste programming isn't perfect, and in the actual run, after the cutting was completed and everything was perfect, a command to lift the router was missing, and it routered a slot back to center position before I could think what to turn off. The "dry run" didn't find this problem because it doesn't lower the router.
   But it was good enough! I added the missing command for nest time. Thanks to CNC precision, this was definitely the most perfectly aligned and best balanced magnet rotor I've done. Somehow in my mind balance at 3000 RPM seems more critical than 2000, even tho the forces should be roughly the same owing to the smaller rotor diameter.
   Of course now I'll do one of these jigs for the larger motors as well.

Motor Assembly

   I had planned to test the magnet sensor board before bolting the stator together. On the 19th, I was ready to close it up. First I tested the board and was glad I did: a solder blob across two traces kept one of the sensors from working (and seemingly blew it), and like the previous motor, the temperature sensor didn't work. The previous motor was also the first time it had occurred to me to try reading the temperature, since I haven't run any of the motors long enough to get very warm since designing the PC board with the temperature as well as the hall sensors. Investigation disclosed that the AD590 temperature sensor part in the Eagle PCB components 'library' was defined mirror image. (I probably defined it myself.) Turning it around fixed it, and I'll redo the PCB design for next time.
   People ask me why I use the AD590 temperature sensor chip instead of a simple thermistor. Well, the AD590 chip is no big expense or complication, and it gives a direct voltmeter reading in degrees Kelvin. (1mV/ºK with a 1K resistor, or 10mV/ºK with 10KΩ - which is also the same reading an LM335 temperature sensor chip gives.) That's instead of some logarithmic reading needing a lookup table (different for each type of thermistor) to match the reading to a temperature, which would essentially require a microcontroller with a display to interpret the reading instead of just a voltmeter.
   On the other hand, a microcontroller would have no difficulty with the linear temperature chip readings, so the chip provides for both options.

ºC = ºK - 273. Max motor temperature = 65ºC. If reading > (273 + 65 =) 338 motor is getting too hot.

   On the 20th I wired up the power plug and the motor was ready to assemble and run except that I wanted to cut 2 shaft keys in the axle - to lock the rotor and whatever load was put on the outside in place. Being Sunday I couldn't buy a 3/16" mill or 3/16" square key that day.

Test and Failure

   The next day I finished it up. On the second try I got the phase wires right and it ran very smoothly... until I tried to speed it up. It wasn't going very fast when there was a clunk from inside and it stopped abruptly. I knew that somehow even at probably only around 1000 RPM, magnets had come off the rotor.
   Four magnets had simply slid out. Their coating - presumably epoxy - was so slick that the (new) epoxy didn't bond to them. There was a second problem: the epoxied polypropylene strapping had ripped up between a couple of the magnets. The zinc coating on the steel rotor had pulled apart, leaving some zinc on the rotor and some on the strapping.
   I added the zinc coatings to protect the rotors from rusting - especially if some of them may be used in marine applications. I wasn't sure if it had ripped because it was inherently weak, or because I hadn't sintered it in the oven as I had on previous occasions. (I simply sprayed the zinc on the rotor while it was quite hot.)

Failed Rotor: slick magnets and weak zinc

Remake (of magnet rotor) and Retry - 1st spec test

   On the 22nd I scraped and then sanded the rotor down to the steel (or mostly just to the parkerizing, if that's what the darker color typically coating plate steel is). Then I cleaned and sanded the 8 magnets to roughen them up, and re-did the rotor, coating the entire rotor face with epoxy to replace the previous zinc and urethane.
   On the AM of the 23rd the epoxy had hardened and I reassembled the motor and tried again. This time it hit a fair RPM with no problem. I didn't push it. I hooked up a clamp-on ampmeter and checked currents. They seemed kind of high. I think these bearings have more friction than the trailer bearings. They improved, presumably as the thick grease warmed up.

   Then I mounted it with an angle iron on the radial arm saw table and used the saw motor to turn it through a V-belt, and checked the readings. On either of two phases, it read 47-48 Hz and 4.7 VAC. Since it has four magnet poles, RPM=Hz*30 or 1425 RPM. Voltage for Kv is the peak voltage, at 1000 RPM, so assuming it was a reasonable approximation of a sine wave out:

Kv = 4.7 * SqareRoot of 2 * 1000/1425 = 4.66

   This figure is somewhat disturbingly low - with a 24 volts supply, full power and no load, the motor might be headed for 5000 RPM. It was supposed to be 0 to 3000. I tried reducing the magnet flux gap by about 1/8", leaving less than 1/8" before the magnets would start to hit the dividing plate between rotor and stator. The reading changed to 5.2 VAC at the same RPM.

Kv = 5.2 * SqrRt 2 * 1000/1425 = 5.16 mV/RPM

   The next day I ran some no-load spinning tests and took some measurements. By the end of the tests, the motor temperature had risen just 15º.
   The Kv of 5.16 didn't seem a lot higher, and sure enough I didn't turn the control up too high (1/4 or 1/3 of the way?) before hitting 2700 RPM. The motor ran smoothly and was well balanced, but the kinetic energy was obviously high at that speed. My instinct said it already seemed dangerous and that I'd feel much more confident calling it a 2000 or maybe 2250 maximum RPM motor instead of 3000.

Below are the no-load spin test results. Note that the currents dropped substantially as the bearings (I presume) warmed up, and power requirements would doubtless have further decreased in a longer run, in a warmer air temperature, or maybe simply after the bearings wear in a while. (See the two 1000 RPM current/power figures.) Unless something else was loosening up during operation, it seemed that the grease in the needle bearings was the main loss factor. In this respect they aren't as good as the trailer wheel bearings -- perhaps simply because I don't grease those too heavily.

RPM  -  Volts  -  Amps -  (Watts)

600   -  25(?)  -  1.6  -  (40W - warm)
1000 -  26.0   -  3.9  -  (101W - cold. This was the first reading after turning it on.)
1000 -  25.1   -  2.5  -  (63W - after warming up)
1500 -  25(?)  -  4.3  -  (107W - partly warmed up?)
2000 -  24.4   -  5.7  -  (139W - warm)
2500 -  24.2   -  8.4  -  (203W - partly warmed up?)

   Later it occurred to me I could check the locked rotor torque with the torque wrench if I could put the square key on the shaft and find a socket just the right size to 'lock' on the shaft with the key. 22mm wouldn't quite go on, but I ground a key down so it would, and did the test. It wasn't much torque for a wrench running to ±140 foot-pounds with 5 foot-pound division markings, but I set the control to 30 amps and pulsed it on for brief periods, and got a reading of about 3 -- 1 foot-pound or 1.36 newton-meters per each 10 amps. The controller's "CRM" constant current modulation, and the spring loaded "momentary on" switch on my test control, were blessings for this test! I tried both directions and moved the wrench to different angles. Torque might have been a little higher in some areas (seemed to read about 4) but it wasn't severe torque ripple. I didn't want to push my luck with (somehow again) my only working motor controller and turn current up higher with the rotor locked to get more precise readings, so I left it at that. But presumably a peak of 127 amps would give around 12.7 foot-pounds or perhaps somewhat more. That's good torque for such a small motor.
   Furthermore, with so little back EMF, that torque and current could well be maintained to quite a high speed. Since:
 motor power out = newton-meters * 2 * π * RPS,
 12.7 foot-pounds (17.2 newton-meters) * 2000 RPM (=33.33 RPS) ~= 3600 watts.
 Since power in = V * A, the maximum power in is 24V * 127A = 3048 watts,
 so obviously we won't maintain full torque up to 2000 RPM. (In fact it works out as full torque to ~1700 RPM, dropping a little to 14.5 N-m torque at 2000 RPM.)
   The current for torque-power calculations is usually measured as the AC current in the motor, which is related to but isn't the same value as the DC battery current. For example, these no-load readings: 1500 RPM, 4.2 ADC and 8.1 AAC on one phase wire. But with locked rotor I got absurdly low amp readings with the AC clamp-on meter, like 20 ADC and 1.6 or 3.8 (or 0) AAC depending on the position of the shaft. I'm not sure what to make of those, except to note that with no load, the current can be way out of phase with the voltage, and volt-amps is then nothing like the same as watts.

FINISHED! Next: measurements, put it in Honda outboard, and future improvements

   The Caik Motor initial development project is finished and the first motor is finished and working. Perhaps students at the local college (where they probably have the equipment) would care to take on figuring out the performance specifications? I sent an e-mail to the head mechanical engineering instructor - one can always hope.

   I'm pleased with the motor and (heavy bearing grease aside) its performance, but I can already see at least three future improvements. The flux gap depends on adjustments of the bearings, clamping onto the shaft from the outside of the motor at both ends. That's very nice for adjusting the gap, but if they slip, it would leave the magnets clamped against the center plate. It would be nice to have a spacer on the shaft to ensure a minimum gap even if that happens. (I have some stainless steel tube just the right size.) I might also make the center plates a bit thinner in future to allow thinner flux gaps with the thinner magnets.
   Secondly, with the magnets puling the rotor towards the stator, the "T" nuts holding the stator end bearing on are under tension. The tops of the "T"s are fairly large and it would be fine for a metal housing, but I'm concerned for the PP-epoxy body. It's tough, but it's not steel. The three "T" nuts could possibly rip through under some unusual stress (like getting dropped or banged maybe). At first I thought some sort of metal ring going all the way around the center hole where the bearing pulls on it would be good. Then it occurred to me that drilling 3 more holes in the flange and having 6 - one bolt and "T" nut between each pair of coils - should provide sufficient support. (The rotor end bearing is pressing rather than pulling, and that bell has more flex than the stator side, and hence is less likely to break. All these things to think about - but better overbuilt than having something bust while you're depending on it!)
   Thirdly, the motor would be easily over-revved at 24 volts with no load, and perhaps even with a moderate load. The larger motors also at least verge on over-revving at full 'throttle'. Preventing this evidently would take a smaller flux gap than is desirable - or perhaps would even require the thicker magnets. The motor controller should have some way to limit the speed, and probably the practical way would be with a microcontroller overseeing the operation. But this is really an improvement to the motor controllers rather than to the motors per se.


Planetary Gear Torque Converter (PGTC)
and Ultra-Efficient Vehicle Transmission Project

Clutch: Pedal, Idler Wheel

   On the 6th it wasn't raining or too cold. I made a mounting bracket for the clutch pedal and installed it in the Sprint car. Luckily even tho it had been an automatic, two nuts were located under the dash for the clutch cable with a hole marked for the cable, and there was a hole at the steering column for one side of the clutch pedal pivot bolt. These were enough to properly locate the clutch pedal and cable in the position they normally occupy. But the rest of the mount for the pedal had to be fabricated, and holes had to be drilled through the outside firewall to meet the bits for the cable on the inside.
   I was going to use steel for the mounting, but the pieces I had on hand were either too thick or too thin. I decided to go with 18 gauge nickel-brass as being the right thickness, substantially harder than aluminum (or straight brass), and anyway much easier to work with than steel. If ever it should start to bend and the clutch pedal creep out of place, it'll either get reinforced as necessary or become the template for a steel one.

Pedal with nickel-brass mounting bracket ready to install in car


Idler clutch pulley and "convenient" bracket... which I probably won't use.

   The weather got worse and other projects intervened.
Mushroom Outboard (Outboard Motor from Scratch) Project

   Well, this isn't getting built very fast. But the new Electric Caik motor gives me compact power to employ in the Honda outboard shell. The idea that the Caik would be 0-3000 RPM seemed to give some promise that despite the 2.7 to 1 reduction in the foot, the motor might get the boat up on a plane. But when I tested the motor, unfortunately for this application I decided it had better be derated to 2000 max RPM. Nevertheless, it should be a good outboard for displacement hulls.

   I took a piece of 1/2" square steel rod and stuck it into the splined socket of the leg drive shaft in the Honda. To my surprise it was virtually a perfect fit. I took a Joy coupling I had lying around and realized that if I rounded the corners a bit, the square steel would fit it perfectly. So, one 2-1/2" piece of steel and a bit of grinding and filing later, I had a fitting in the outboard. On the 24th I bought the rubber center piece and the Joy coupling to fit the motor shaft, and it's done. (Amazing how a shopping trip can eat up a whole morning or afternoon.)
   The next task will be to mount the Caik motor in the outboard. Then it'll be ready for a test run.
   After that I can get back to trying to cast the airfoil shaped propeller that I suspect is more efficient. If I chop some off the end of each blade it would fit the Honda, and then I can see if this somewhat butchered version works better than either or both of the props I already have. If it does, great. If not, it only proves that the chopped blades don't work better, so I'll still want to try the "real deal" on an "outboard from scratch".

   On the evening of February 2nd, I took the Caik motor out to the garage to see how it would fit in the Honda outboard shell. With the 2011 rear bracket (blue) fastened, everything seemed to line up nicely with the motor shaft right over the drive shaft in the leg and the joy couplings mating nicely, and on the spot I started working on it and spent a couple of hours on a front support and getting it all ready. It just needs a flat plate and some bolt holes drilled.
   Were it not for the existing rear bracket I'd have mounted it 1/2" to 1" lower, but the hood fits on with about 1/4" or more to spare on all sides.

Fitting Electric Caik motor into Honda outboard shell


Turquoise Battery Project

Methyl Benzene (Toluene) to increase Positrode conductivity

   Current capacity of the new cell was poor. Since the iron electrode had worked well in the Changhong cell, I assumed the problem was the KMnO4 posode. I realized soon after making it that I hadn't done a conductivity test and that there wasn't enough graphite powder in proportion to the other ingredients. It was probably below that threshold where conductivity rises rapidly with just a few more percent of graphite.
   A few cycle tests with a 50 ohm load seemed to indicate the operation was stable with cycling. I removed the electrodes and dried out the posode, then applied 4 eyedropperfulls of toluene. The first 3 soaked right in. The 4th took longer, presumably indicating I'd saturated the electrode. It was doubtless overkill.
   Methyl benzene (toluene) is supposed to dissolve graphite in order that it'll form carbon nanotubes (Wikipedia). In the electrode with a the graphite current collector and containing graphite powder, the toluene evaporates, leaving (according to my theory) random conductive paths of carbon/graphite lamilae and nanotubes. (I suppose I could see this if I had a scanning electron microscope.) Earlier tests on "grafpoxy" current collector rods seemed to show about a 40% (IIRC) drop in surface resistance, and in other tests 'expanded graphite' sheets - and the surface of the electrode they touched - acquired a silvery sheen.
   On the 12th I put the cell back together. On the morning of the 13th after a very disappointing load test I found that the cell didn't have enough electrolyte -- I'd been fooled by a bubble across the opening that made it look full. A couple of tests later in the day showed that conductivity seemed considerably improved.

MnMn or MnMn?: troubles with Fe

   The new cell, supposedly Mn-Fe, would charge up to well over 2 volts, the voltage for Mn-Mn, instead of maybe 1.6 or so. I consider that the posode initially loses a little unchelated KMnO4 into the electrolyte. The MnO4- ion finds its way to the negode and discharges to MnO2->Mn2O3->Mn3O4->Mn(OH)2->Mn (all solid, the last metallic), coating the negode with Mn as a higher voltage surface charge.

   Worse than having two voltages, the already low amp-hours capacity of the lower, iron, voltage apparently decreased first when it was removed from the Changhong cell and left sitting for a while, and second when it was removed while the other electrode was 'toluened' to increase conductivity. My take on this is that the lower level of alkalinity in my 'moderately alkaline' cells doesn't provide the iron corrosion inhibiting properties of pH 14, and that some of the iron was turning from conductive ferrous (Fe(OH)2) to non-conductive ferric (yellow or red rust, Fe(OH)3) state at the slightest excuse. From the chart this apparently shouldn't be very pronounced above pH 7, but it does gradually happen even at pH 14. Add to that the band "g" where it appears one must use a higher voltage to charge the iron to metal (bottom of 'g') than is retrieved during discharge (top of 'g') and we see the known inefficiency of charging an iron electrode. While it appears to work surprisingly well at pH 14, iron would seem to be a poor choice of electrode material at lower alkaline pHes. Instead manganese becomes the "right stuff", and anyway has higher voltage.

Manganese!

   I've sung the praises of manganese as a battery ingredient for both electrodes before, but here's another perspective. A great beauty of manganese is that in every state of oxidation from Mn metal to MnO4- (valence 7), it has electrical conductivity. It can electrically charge or discharge all the way from one end to the other; it can't be passivated, which is the chief factor limiting the life of most batteries. All the states except permanganate are also insoluble.
   Other researchers have shunned it as a rechargable positive because of the slight solubility of the KMnO4 oxidation state. I use chelation with sulfonates (as in Sunlight dishsoap) to fix even the dissolved ions in place. And it's been ignored as a possible negative because it self discharges at pH 14. I use a lower pH electrolyte, plus antimony sulfide to raise the hydrogen overvoltage.
   MnMn in moderately alkaline electrolyte still appears to me to be the outstanding choice for a high energy density and "forever" cycle life battery cell.
   Vanadium-Manganese (VMn) would have about another 1/2 a volt (and I may make one just to see a 2.7V alkaline battery), but lower amp-hours by weight and volume since the reaction V2O5 => V2O4 [+1.5V] only moves one electron per vanadium, instead of three per manganese for MnO4- => MnO2 [+1V]. And vanadium costs notably more than manganese.

Production Battery Cells

an initial concept
   On the 20th, since I thought I pretty much knew in almost every detail what I wanted to do to make production MnMn flooded cells (along the lines of last month's writing), I decided it was time to bite the bullet, make all the needed tools to make them and design the 3D plastic pieces, and try making some. This seems something of a gamble, but with yet another test cell oozing salt out the seams and discharging itself, it seems making test cells has been something of a losing proposition and isn't providing any more especially useful results.
   I decided to make electrode briquettes strongly compacted from one end with a screw press, avoiding need for a 45 ton press to compact them well on the flat. But from the pocket electrodes I'd take the best feature: a plastic grille to separate the electrodes and provide a narrow free space of vertical columns for gas to bubble out.
   A last piece of the puzzle seemed to be the one-way air block/pressure relief cap mechanism. The small glass 'marbles' were larger than the planned thickness of the cell, and not all that smooth. I had been avoiding metal, but I finally decided to try stainless steel ball bearings. They shouldn't corrode since they won't be in contact with either electrode. In theory. The second point was the smoothness of the lip of the plastic hole they cover. For this it finally occurred to me I could make the holes slightly undersize on the 3D printer, and then drill or ream out the lip to a smooth bevel.

   On the 21st I printed a prototype case that included all except one face, and I cut that side from a piece of 1/16" ABS sheet. It looked good except for a couple of omissions.

   My previous steel boxes for compacting electrodes would get dirty and when I washed them they'd rust. This time, on the 23rd, I cut some pieces of .1" stainless steel for the new box, and polished the inside faces mirror smooth. This box accepts material from one end, and a bar is pushed in and compacts it from that same edge. By compacting from the end, only a fraction of the pressure is needed compared to compacting on the flat, eg maybe 1500 pounds instead of 70000 for the electrode size I've selected, 63 x 63 mm. When the briquette is complete, I had hoped to simply push the briquette out the far end. But it didn't work unless the bolts were loosened off. I finished the box to usable state on the 26th.
   A drawback to compacting from the end is that no grill can be compacted with the briquette, as it gets munched down towards the bottom end. (I tried it once.)

   On the 27th I printed a more complete battery cell box, and then made some center bubble-up grills to try out. Seeing how they fit, I then designed a further improved box with lips for the lower separator paper. I hope I might just get the whole thing down to dropping in the internal components and sealing it up, without very much fiddling around, and every time I had an idea or two, I printed an improved case.

Punched current collector contact sheets with sewing machine

   It seemed to me that rough material would contact the briquettes far batter than the smooth sheets of flexible graphite and zinc. But what rough material? I've never seen a zinc mesh or grill. I dislike working with carbon (graphite) fiber, but perhaps that would be an option to make a "grill" for the positrode? Of course, there would be no way to electrically bind it to the current collector except by random contact.. or perhaps by winding it around the whole sheet.
   I realized that holes could be punched in the zinc sheet and could give nice jagged edges, but punching one hole at a time seemed absurd. I could put some sort of punch on the CNC machine, but it would take ages. Or could I make some sort of thing with rotating pins?

   Suddenly on the morning of the 25th I thought of the sewing machine - just punch a bunch of holes all over the material with the needle. Unfortunately a few months ago I sold the powerful Singer 503 (for 1/2 what I paid) since I wasn't punching plastic pockets now that I had the 3D printer, and it had been just sitting around. I'm such a packrat, hanging onto tools and materials "just in case", but I told myself here was something I really didn't need any more. Rong!
   My old, slow machine did manage to punch holes in the zinc - barely, slowly, unevenly. But the effect was good. The many holes have ragged edges sticking out, perfect to dig into the briquette and make good electrical contact.
   I punched the graphite sheet as well. This didn't even slow the machine down, but the soft protruding hole edges will mush down when the briquette presses on it. Then I thought to use a broken needle with a flat end. That makes somewhat bigger holes. The holey graphite is probably an improvement over the smooth sheet.
   I was pretty sure the zinc would be great, so if the graphite worked well I'd have good hopes of getting decent current capacity. It seemed poor. If it doesn't improve I can try the carbon fiber.

   At last there seems to be hope for making practical high energy, low cost, long life batteries in the near future. It may just hinge on making really leakproof cases.

   On the evening of the 29th I made a positrode. I used about the same permanganate-nickel-graphite mix as last time, with a bit more graphite added to it. I removed the top plate from the book press to get more pressing height, making a very nice screw press except that the screw had no non-turning end piece on it. But it was good enough and the compactor seemed to compact very well. I added more and more of the powder until 20 grams had been consumed. (From which one might estimate 5 to 8 amp-hours capacity if utilization is good.) Even then it wasn't quite full size. Because I had made one side of the compactor exactly the 63mm electrode height, it was hard to add powder to get it right to the top without it spilling. If I pressed it hard enough, the 2.6mm stainless steel bulged. (.1" was the thickest piece of flat stainless steel the recycling place had at the time.)
   The part of the plan to support the edges and push the briquette out the bottom didn't work. It wouldn't budge. At least it only had four bolts to undo. (On the next one I found it could be pushed out if the bolts were merely loosened.) I'll want to improve on the compactor box, and put a bottom on the screw press screw, but it's okay for a few cells. The electrode had a dull silvery sheen (compacted graphite) and gave ohmmeter readings in the low to mid 100s of ohms. That seemed good for the relatively small concentration of graphite before the toluene treatment.

   However, when it was placed in the cell, it was too thick. It stuck up about 1.5 mm or more above the shoulder I printed into the case for the top of the positrode and the lower paper separator. That's all around, so it doesn't even include the center bulging. How .5mm plus 2.3mm adds up to 4.3+mm thickness I'm not sure, but on the 30th I made a case 12mm thick instead of 8, with the inner shoulders 2mm higher and 2mm more for the upper electrode as well. (They'll stand up better and have more room for the filler caps anyway.) Of course, I could make thinner briquettes and have these for thinner "high rate" cells. Perhaps I'll try that out, as I've already printed a couple of thin cases.
   In the meantime, I printed a taller top basket for the thicker cell case.

Evolving case designs: top L: basic idea, R: add filler hole surround
bottom R: add barrier to positrode material escape (but bar printed hollow), L: improved version with graphite sheet.
Next version (not shown) was 12mm thick instead of 8mm.


Evolution of separator frames from just gas bubble channels into baskets to contain edges of negode.
Top: off-center edges 1.2mm, better 1.2mm, .8mm but hollow bar (printer's fault at specific widths)
Bottom: (hollow) basket edges, better edges, Thicker basket (not shown), thicker and with cutouts at top for case variant.


Evolving filler hole cover ball spring clips (they hold the ball in the filler hole):
Too short, too long, right length, add squirt guard, better squirt guard.

   On the 31st I mixed ingredients for the negode, and stuffed 35 grams of the mix into the compactor - theoretically over 20 amp-hours of manganese! It won't attain that, and the posode had less than 1/2 that anyway. (I could probably make this side much thinner than the plus.) I then finished assembling the cell and glued the outer face on.

Mn Negode pushed out of compactor after loosening the bolts.
The silvery sheen is mainly from the (20%) zinc powder, but initial conductivity was surprisingly poor. More zinc next time?

Benign Failure Mode

   Somehow I gradually removed most of the batteries from my solar PV system, over time and finally to use to run the Caik motor, and then came about the only really sunny day in late January, with lots of solar power. Somehow the DC to DC converter was putting out over 14.4 volts, and with less current being drawn by the few remaining batteries, the schottky diodes had less voltage drop. An excessive voltage of over 14.2 volts over enough hours was too much for some cell or cells, and the battery (my first original NiMH car battery of January 2011) overheated. When they do rupture, they seem to short circuit, or at least have a lower voltage, and the nearby cells get even more voltage and start burning out. My first clue was faintly smelling burning acrylic plastic from the hallway downstairs. Upstairs when I opened the door, my office was filled with acrid smoke! I shut off the solar 12 VDC main panel breakers, got gloves, disconnected the offending battery, which by now was 60 smoking "4/3 A" cells perhaps about ready to burst into flame, and took it outside and hosed it down.
   I had considered that dry cells were pretty safe to use indoors, but I'm very glad I was home and about when this happened. (Less than an hour earlier I had been in the office and there was no sign of trouble then.) I dropped the DC to DC converter by .2 volts and hooked up some more batteries to share the charge, and I'll add protection soon (a fireproof metal box off the floor... or fire bricks... comes to mind).

   But that got me thinking about the batteries I was making. They're wet cells and overcharging will give off hydrogen and oxygen just like lead-acids, albeit less since the cells and the amount of liquid are smaller. Aside from that, the two electrodes each have their own paper separator, and between the separators is a .8mm gap, designed as a passage for gasses to bubble up from anywhere inside to the surface. If the cells are overcharged and gas is emitted long enough, the water level will get low, and finally it will boil (electrically) dry. As it does its resistance will rise and more voltage will drop across it, accelerating the boiling. But the current will drop and charging of the other cells in that bank will be reduced. Once it's dry it becomes an open circuit and charging of that bank ceases entirely. Assuming the gas has been vented safely, the cell may be refilled and no lasting damage is done. This is a much more benign failure mode than the NiMH dry cells exhibited, but obviously the MnMn wet cells shouldn't be kept in an unventilated closet either.

   A related interesting aspect is that with spring clips holding the balls on the filler holes even against slight pressure, these flooded cells could be tipped over for a short period, theoretically without leaking - or perhaps with 'minimal' leaking. It certainly wouldn't be an advisable operating mode, but it should ease concerns about using these batteries in mobile situations, eg, what happens if a bike accidentally falls on its side, or what about boating in choppy waves where the electrolyte may be well shaken?

Battery Cell Assembly Procedure (tried once - subject to change)

1. Prepare the internal components:
- Positive current collector, positive briquette, positive separator paper, separator basket,
negative separator paper, negative briquette, negative current collector.

2. Prepare the case: Sand the outer outer face edges flat and smooth with a big piece of sandpaper on a flat surface, file or cut out sags in the 3D printed posode terminal slots, drill out filler hole to 1/4", put in 5/16" ball bearing and run a little methylene chloride around it so the lip of the hole conforms/melts to shape of the ball (trim thin scrap created in hole if necessary).

3. Cut & prepare the top side sheet plastic piece.
(70 x 100mm + 20 x 20 mm negode tab.)

4. Slip the 'flexible graphite' positive current collector tab under the slots and position it in the 65x65x4.0mm lower box.

5. Fill the top slot with heat glue so the terminal won't leak. Get some in behind too, with a thin knife or something. (work fast on that.) (This step may optionally be done after assembly is complete. If you break the graphite now getting some glue under it, it's easy to pull it out and start over.) Also heat-glue the top end of the inner slot to prevent escape of electrode material through the tab slot into the upper chamber. (must be done now.)

5b. Optional: surface treatment of graphite current collector to improve surface conductivity: acetaldehyde doped with osmium. (More on this later.)

6. Place the posode briquette in the lower box on top of the current collector.


7. Place a piece of 69x69mm watercolor paper on top of the briquette.


7b. Before 7, fold a little piece of paper with a 3mm edge. Place it over the briquette and fit the fold pointing down between the briquette and the upper wall. This should help keep briquette material from escaping from under the flat paper into the upper chamber.

8. Place the separator basket on top of the paper. Press the edges down and glue it in (3 edges) with methylene chloride. Let it harden.


9. Drop 5 to 10cc of toluene (methyl benzene) with a dropper at various points into the basket/paper/briquette/graphite to absorb in and dissolve graphite powder. The graphite will form more conductive random lamilae and nanotubes to improve conductivity as the toluene evaporates and it solidifies again. (around 40% more conductivity) Give it some hours to evaporate. (until it doesn't stink of toluene.)

10. Place a 64x70mm piece of watercolor paper into the basket, folding it up the side of the basket at the top and bottom (where there are no lips at the edges).


11. Place the negode briquette in the top basket, on the paper.


12. Place the zinc current collector on top of the basket with its terminal extension sticking out the 'minus' slot.


13. Run a bead of methylene chloride around the outside edge of the case and put the top face on the cell. (Avert your nose. Wetting the fingers with it seems okay but it's not good stuff to breathe.) Clamp the cell in a book press or put a flat heavy piece on it to hold it closed while the solvent evaporates and the plastic hardens.

14. Use heat glue to seal the "+" terminal slot, including some between the zinc and the plastic tab.

15. Punch a hole in the graphite and in the zinc terminal, put in brass or stainless washers and machine screws and nuts. Loosely put on a second nut to attach connection wires.

16. Fill with electrolyte pouring from a beaker, using a fine funnel, small flex hose or ?. Liquid level should be above top of grid. (If you can find translucent or transparent plastic for the flat face, its great for seeing the level! Note: acrylic plastic will crack to pieces if it contacts toluene.

17. Place 5/16" ball bearing on filler opening and put cover clip over it.

   Now it should be charged to about 2.4 volts. Then it needs to rest quite a while, during which it'll self discharge considerably. Then recharge. It remains to be seen if it's a good idea to change the electrolyte after initial use to eliminate any soluble impurities. That might also depend on the source of the ingredients.

   Below is the first 'production prototype' initially charging on the 31st. (I did the hole and bolt in the zinc terminal later.) Initial filling of the cell resulted in lots of bubbling, presumably as MnO2 and Mn metal interacted, and some zinc, especially the powder, was doubtless also being reduced to oxide. This reaction might have been reduced somewhat had I remembered to torch the negode before I put the cell together, which should have converted some of both the MnO2 and the Mn metal powder to MnO, Mn3O4 or Mn2O3.
   I also sanded the edges just enough to take off any high spots made by the 3D printing. I thought the glue would solve any slight dips, but I had trouble with the seam leaking, and patching with "plaster" of ABS saturated with methylene chloride was difficult and took several tries. (Sigh!) For the next cell I've sanded the outer edge until it's definitely flat all the way around.

After further charging, the voltage sat around 2.4V. pH was about 12 to 13.

Here's the next case and basket, with the next refinement: the basket can't slide up towards the top while it's being glued into place. (Picture was before sanding edge.) I have further improvements make to help prevent leakage of electrode materials into the upper chamber. Those'll be for next month.



http://www.TurquoiseEnergy.com
Victoria BC