Turquoise Energy Ltd. News #14
Craig Carmichael - April 3rd 2009
Highlights - Contents:
March in Brief
* Electric Hubcap (Preliminary) Motor Making Manual Uploaded.
* Much work on web site - more to do.
* Icy weather impedes car/outdoor work.
* First driving attempt ("Production Prototype" motor): Motor moves car but is not quite yet fit for street.
Items below are posted on the Turquoise Energy
Ltd. website. Only the highlight blips are included in this email.
* "TheWheel": electrically similar wheel motor makes many performance claims very similar to Electric Hubcap.
* they are even more optimistic about average direct-drive PMSM energy savings (50%) than my estimates (33%).
* bulkier, heavier, costlier & can't retrofit existing cars
* Their large model is running ultra-efficient hybrid busses.
Electric Hubcap Car Drive
Project, Longwinded Detailed Report
* Calculations show current phase lag is a non-issue for EH 3-phase power timing.
* Evolving designs of terminal blocks for heavy wires.
* Slow, steady progess on small details/problems during March.
* First moves car March 26th.
* After all my figuring... timing adjustment seems needed.
Turquoise Battery Project,
Longwinded Detailed Report
* A problem identified: cellophane needs chemical surface
treatment for use as electrode separator sheet.
Electric Hubcap Motor Making
* Hybridize your car (or other motor project).
* Workshop cost re-examined: $2750 all inclusive?
Innovative Product Developers
* Meeting: Sunday, April 26th 2009, 1:30 PM, 820 Dunsmuir
Rd, RSVP, 384 2626 (there's no article, just this
Complete newsletter: http://www.TurquoiseEnergy.com/news/TENews14.html
I uploaded all the
previous newsletters to the Turquoise Energy Ltd. website, and worked
on the preliminary construction/installation manuals for the
"production" model Electric Hubcaptm (EH) motor and uploaded it. These
tasks were a major occupation for the month.
When motor and appliance manufacturers discover on-line my
"opto-electronic commutator", it will facilitate adoption of more
efficient and flexible PMSM motors (including my axial flux motor
designs) in place of induction motors, in everything from washing
machines (especially!) and refigerators to shop tools and industrial
equipment. Here is a "spin-off" benefit of my R & D work to the
progress of civilization! As is typical of such novel designs, it's not
practical under existing rules for the inventor to attempt to gain any
reward from it.
Someone pointed me to another direct-drive PMSM car wheel
motor. E-Traction's "TheWheel" makes many of the same claims as my EH
claims, but estimates 50% energy reduction where I've more
conservatively been saying 33%. The EH should actually have an edge in
efficiency, and their motor, as designed and configured, can't be used
to retrofit existing cars.
I picked away at the actual motor project, generally for
an hour or two or three most days amongst many other things. Weather
(rain, snow, and continuing icy temperatures to March 33rd) and other commitments got in the way. Various minor
problems were gradually identified and overcome. (Some were unseen
& unsuspected "leftovers" from February's battery spark problem.)
By the 26th everything seemed to work, but the motor had
little power. It spun better in reverse than forward. It moved the car
slowly on level pavement, and nothing blew up (a tremendous plus!), but
obviously there's still a problem. Judgeing by the high currents,
the timing must be off... somehow. (I thought I had the timing all
On the 28th I finally(!) found a nice "wok cover" end cap for the motor with its protruding trailer axle.
The "dressed up" motor on the ever elegant '84 Tercel wagon.
The sign, "Do you want to hybridize your car?", is really there as much
to answer the inevitable question "What is it?" as to attract workshop
The 31st saw the motor removed again to install a
"ligature" clamp (clarinet players will be familiar...) so the optics
board can be rotated to find the timing angle for optimum performance.
Sigh, another month and I'm still not driving electrically!
Here's a direct drive PMSM wheel motor design from Holland,
that's electro-magnetically very similar to mine. But while this design
is reversed with the rotor and magnets at the outer rim, it still uses
radial flux design and so their motors will be heavier (and it's
unsprung weight), more complex and expensive, and too fat for the
outside of a car wheel.
E-Traction direct drive wheel motor for hybrid busses - They're getting very close!
A news report on it: http://mobile.technologyreview.com/energy/22328/page1/
The company: http://www.e-traction.nl/
As they are also using a PMSM motor of large diameter, they make some essential claims very similar to the EH:
|E-Traction TheWheeltm Claims:
(quotes clipped from website)
|Turquoise Energy Electric Hubcaptm Claims: (roughly as previously stated)
|"more than 90% energy efficiency"
||probably over 90% efficiency. (...and doubtless a bit higher than TheWheel's. [improved coils])
|"delivers up to 15,000 Nm"
||High torque at any speed from 0 up
|"direct drive traction at the only place where it matters, .....at the wheel"
||Direct drive efficiency: no gears, no transmission; the car wheel IS the rotor of the motor.
|"The greater the diameter of the motor within the wheel, the greater the torque."
||The axial flux Electric Hubcap's effective diameter is
much greater than a typical radial flux motor, providing much more
leverage of the magnetic forces, for much more torque. (same meaning)
||Good air flow cooling eliminates the
need for a liquid cooling system with
its added complexities and weight.
"On average TheWheel™ uses
only half the electric energy of a typical geared traction motor."
|<>Average of 50% better performance
than a typical geared electric vehicle drive. (Ie, uses only 2/3 the energy.) (same meaning; differing estimate)
Since the drive efficiency of EH should be marginally better than E-Traction's, if their bottom line estimate is accurate, evidently my estimates of the savings have been erring substantially on the conservative side.
Egads!, except for being fat, heavy and expensive, this concept looks a lot like the Electric Hubcaptm!
As designed, they won't go on the outside of a regular car wheel, but
if they switch to axial flux, it'll be very serious (and obviously well
This is probably one good reason for going "open source": putting all
the tech info onto the web so anyone can make and install them. The
Electric Hubcap will beat them into the open market, or at least the
north American market. Then Turquoise Energy Ltd.
with minimal financing can start to produce complete car hybridizing
kits plus key motor & controller making parts for small garages and
home workshops, with a big headstart on anyone else, for a rapidly
self-expanding market that will soon become high volume.
I'm sure a kit for $1500 to hybridize an existing car (excluding
batteries, of course) is doable and would be a big hit! Getting the
price down to $999 would be gravy.
According to the specs shown, the one electrically most similar to EH is their SM350/1, which doesn't mount on a wheel:
Power: 6.0 KW (versus 3.6 - 4 KW)
Amps - nominal: 150 (versus 100 - 110)
Amps - peak: 300 (versus (?)150)
Torque: 150-200 Nm, 600 Nm peak (versus ?)
Weight: 85 Kg (versus 22 Kg)
Diameter: 378mm (vs 330mm)
Length: 275mm (~80mm+)
Four notable specs are the power - theirs has more; the peak amps - the
EH protection circuit seems to have it under better control; the weight
(85Kg unsprung!); and the width - theirs is almost 11 inches!
I haven't been able, without equipment, to measure the torque of the
EH. In my one attempt with a 25 pound fish weigh scale at 6" radius,
the scale hanger immediately broke, the pieces flying off with force -
and IIRC that was with 12 or 24 volts, not the full 36.)
They are developing or have a new model specifically for cars, the
SM450. Torque is claimed as 400 Nm on one page and 1200 Nm on another.
It's not shown on their specs chart with the others. Wheel diameter is
450mm (~18"), necessitating a thin wall "low profile" tire.
They may get the weight down to where it's usable on a wheel made
specifically for it, but they aren't going to get the sort of weight
that can make it into a low-cost add-on for an existing car, which is
where the high-volume business opportunity lies.
Although there are many similarities, they are going to have to
considerably alter their designs if they are going to compete with the
Electric Hubcap, but it would certainly appear they have the resources
and the know-how to do so if they wish once they've seen the Turquoise
Energy website & the Electric Hubcap designs.
HubcapTM Vehicle Drive Motor
On March third I
thought the controller was ready to put in the car save for drilling
some holes for screws to attach it. That night I had a dream where I
was checking out the motor controller. A voice said "It's only
prudent to test the pins" - nothing vivid, just a few seconds.
Okay, then... ready except for screw holes and testing the transistor
On the fifth I got to
it again, and put the ohmmeter on it. I had decided to remove the
wires (some rather crispy) from the bottom of the circuit board to the
transistors, and solder new ones on the top side. I couldn't see the
circuit traces, mostly running on the now hidden bottom of the mounted
board. There was a short circuit and two identical wrong connections,
any of which would have kept the board from working and possibly fried
it in short order!
Of course, that board
was made with a completely different layout in mind and is now rather
chaotic. The production board layout (that I have yet to tackle) will
be set up with the connection points all in an orderly row along the
New aluminum wiring box with controller spread
across the lid. Not quite visible here are the "fan" heat sink
fins of aluminum roofing flashing clamped on the outside of the cover
behind the big transistors.
On the 20th, I finally
got up the courage to try 36 volts. A couple of MOSFETs and their
fuses blew. On the 21st, after fixing (yet another) problem on the
circuit board (probably created by the February burnout), I spun it
with 36 volts and it seemed fine.
But when I
disconnected the test controls and hooked up the real operator
controls at the front of the car, things started going wrong again.
The motor took off like a banshee without touching the gas pedal, as
soon as I clicked the switch on. The low-speed protection circuit
wasn't limiting the current, and It blew all the fuses. Not yet aware
just what was happening, I put in bigger fuses, 40 A instead of 30 A
(80 A per phase instead of 60 A). Two of those blew almost the moment
I flipped it on.
I must say, I'd
become almost terrified to run tests lest I again end with a
controller on fire and all the main driver parts blown. Blown fuses
instead is a vast improvement, a hidden advantage of having a
protection circuit that limits normal current to under their ratings
even at startup!
Finally I measured the
resistance of the gas pedal potentiometer. Open circuit! I found a bad
solder connection on the wire at the plug and fixed it. STILL
But even as I checked
it out I realized that a control defaulting to "over max"
instead of "off" with any typical problem was not a positive
design feature. The circuit will have to be changed.
On the sixth all was
ready and I started to install the controller. As usual I had a hard
time trying to get the marette connectors onto the three sets of three
heavy #8 wires. It was a continuing headache: I remembered spending 25
minutes one time making these three simple triple
Surprisingly, such terminal blocks as exist (besides telephone wire
blocks) seem to only tie two smaller wires together, not three and not
heavy ones. I guess electricians usually have lots of room and wire
length for the marettes, which do after all make good
But enough was enough!
I made a wooden connector block with three 1/4" bolts sticking
out to hold the wires. This necessitated soldering lugs on the wires
(and buying them).
Somehow that seemed to
use up the whole afternoon.
sunny afternoon was followed about 10 days of rain and snow! ...in
Victoria ...in March!
In the paper on April first was something
about a "Pacific Decadal Oscillation" (PDO) bringing cold weather to the
west coast. It must have been an "April fools" article... it doesn't explain the cold temperatures elsewhere and no mention was made of the fact that the last 10.7 year
sunspot cycle was (IIRC) over 12 years long, the weakest on record,
which will naturally bring a decade of cold, wet weather (worldwide),
after the strong cycle that brought the warm 1990's. Shortest (strongest) cycle since they've been recorded
brought the 1930's "dust bowl" years.
Someone said one day in early March that it was -45 (!) in
Edmonton. I grew up in Edmonton and it was Never that
cold! About -30
(F), in December or January, is the worst I can remember! Even in absolute
temperature terms, 228 degrees K (-45 C) is scarcely 3/4 the thermal
energy of a balmy summer day (300K). But I digress.
Wire Connector Block #1 in fine Cambodian rosewood,
with terminal bolts protruding
Underside of block, showing recesses to prevent bolts touching chassis
After I installed it, it looked like the lugs could potentially twist around
and short between the posts. I could work around that, but I decided
it just wasn't a very good arrangement for a final
What I had really wanted all along was something like the screw-down strips
found in circuit breaker boxes for the neutral and ground wires. So I
decided I would just have to make something like those.
I bought a 3/4" square rod of copper.
walked in my front door with it, I had a sudden flash of a much easier
to make connector block that didn't need the solid copper piece at
all! But since I'd just bought it, and since it seemed like a very
good design, I decided to persist.
end I drilled a left and right side hole right through it, big enough
to insert #8 wires. Then I cut it to 1/2" long with an angle
grinder. Into this "cube" I drilled and threaded smaller
holes for "machine screws" (AKA small bolts) to clamp the
wires down with, and a center hole for a mounting bolt.
Off the wires came the lugs, so soon after soldering them on! (That's
product development - the instruction book has yet to be written;
"standard practice" has yet to be worked out!
Second version connector block, in Pacific Dogwood.
This is the one I used.
(The same mounting bolt pattern as the previous
block was retained, so I didn't have to un-mount the wiring box and
make more holes.)
But, having thought of another and simpler way of doing the same thing, I
just had to try it out! This idea used short sections (1") of
small "1/8 inch" (actually larger) threaded brass plumbing pipes. These have a
thick wall... evidently for threading a bolt into! Making an
unfinished sample (one pipe) took less than an hour. The pipe was big
enough to stick in a #6 wire, or two #8's. One set of threads stripped
when I tried to do up the bolt. I turned the pipe over and drilled 2
slightly smaller holes in the other side. It was tougher threading
them, but the result seemed more solid - at least, I did them up
pretty tight and they didn't strip.
Third version connector block, in hard, gorgeous Lilac wood.
The wire clamp bolts hold the brass pipe in place with no
extra mounting bolt.
The pipe can rattle around just a bit.
I note that the inside
of the pipe was a bit corroded, whereas since I'd just drilled it, the
holes in the copper cubes were clean and shiny. Probably the brass
pipe should be cleaned inside before use, which (unless you can think
of an easier way to do it than filing it) probably negates some of the labor
So that was four evolving versions of connector terminals counting the original
unsatisfactory marettes. The copper cubes is doubtless the best and
most reliable version.
I suppose I should rejoice that some sort of custom terminal block like that will
doubtless be one of the products Turquoise Energy will supply to
people who want to make and install their own motors.
I also think a heavy cable "slim-line" in-line plug and
socket at the wheel to replace the marettes for the motor is in order.
(There isn't room for
the bulk of a regular type stove plug and socket, unless they stick
out from the side of the car.)
Inductive Phase Lag
One day I thought of a new aspect of motor operation I hadn't previously
considered, and feared it might be significant. Up to that point,
I'd been thinking "This is great, this optical system provides
ideal timing for the coil drives, both forward and
But the current in an inductor, and hence the magnetism, would lag behind
that "perfectly timed" applied voltage. Was the lag trivial,
or was it enough that the timing depended substantially on the RPM?
Did it need something like a centrifugal timing advance?
The more I thought about this, the more concerned I became. After all,
I've had to rework virtually every aspect of the motor at least twice
since I started owing to failure to take various things into account.
I keep finding ignorance isn't usually bliss when designing something!
I finally decided I should check the inductance of the coils so I
could work out the phase lag. (Oh no! - math and formulas,
I traded a couple of supermagnets to someone who wanted them for the use
of his super-duper multimeter that measured inductance, capacitance
and transistor beta along with the more common functions. One lone
coil read 0.60mH. (Later another meter verified the reading, showing
0.58mH.) I had thought it would be way higher, but what do I know? Any
two phase wires of the assembled motor stator also read 0.60mH, the
same to two decimal places, a seemingly odd co-incidence as any phase
has two sets in series of three coils in parallel. If they were 6½
resistors, we'd expect 4½, but coils in proximity, ie all packed
onto the same rotor, interact magnetically to increase the inductance,
and evidently the result happened to be identical to one lone coil.
(Other loops of wire and the other stators gave quite different and
Given the inductance figure, we can derive the rest.
A = V*S/H.
where A = amps, H = henries, V = volts, and S =
First we want the time lag, seconds, to "full" current
at maximum drive, so:
S = A*H/V
S = 90 * .00060 / 36 = 1.5 mSec
Then we want the angle the wheel rotates in 1.5 milliseconds at
maximum speed. We'll call maximum speed 130 Km/Hour. The fastest that
will typically be is with a smaller 13 inch wheel, 1300 RPM. 1300
R/Min = 21.67 R/Sec. In each rotation there are three electrical
cycles, one every 120¼, so 65 cycles/Sec or 0.01538
not trivial. Even considering half the current is flowing (or has
stopped) by 6¼ lag, if the math is right it's probably just within
limits for good operation. But that's the most extreme case: top
highway speed with the smallest wheels and "pedal to the
metal", so I'll consider that variable timing is unnecessary.
(Whew!) At 3000 RPM, or perhaps even 2000, we just might have to
consider means of varying the timing by RPM and current flow.
0.0015 sec phase lag / 0.01538 seconds/cycle = 0.0975 cycles
0.0975 cyc.lag * 120 ¼/cyc = 11.7 ¼ maximum rotational
What about a more "typical" case, 50 Km/Hour at half
S = 45 * .0006 / 36 = 0.00075 mS
S = A * H / V
500 RPM / 60 sec/min * 3 = 25 cyc/sec or .04 sec/cycle
.00075 / .04 = .01875 cycles lag, * 120 ¼/cycle = 2.25¼
if my math and parameters are right (both a big IF!), it might be well
to advance the timing slightly, about a degree. A degree fast at very
low speed (also resulting in a degree slow for reverse) should be
trivial, and reduces the max 11.7¼ on the highway to 10.7¼. But I
will by no means guarantee that my timing slots, or the magnets or the
coils, are placed to within 1¼ of accuracy to begin
looks like in this particular instance, ignorance was bliss after
Progress has been slow on the
battery project as I strive
to get the car running on the Electric Hubcap motor along with other commitments.
Luckily, I know
batteries do work. I'm now working with nickel and zinc, both well
known battery electrode elements. I suspect my main problems boil down to:
* poor sealing - gas leaks
* the electrode separator sheet (evidently the main culprit)
As to electrolyte, notwithstanding it's
what others have done, I don't want to use potassium hydroxide,
alkaline, electrolyte unless no neutral or acid solution works, as the
nickel hydroxide has the least available energy, both amp-hours and voltage, in
alkali solution. Neutral or acid is the key to getting higher energy
density. Potassium chloride (KCl), hydrochloric acid (HCl) and perhaps magnesium perchlorate (MgClO4)
should be good compounds, probably in a mixture. The zinc probably
requires a mixture at least somewhat acidic rather than neutral.
Looking over some
patents, it seems the cellophane needs some treatment before it will
work as an electrode separator sheet the way I've been expecting it
to: not just cellulose but cellulose ester or cellulose acetate or
On the 20th, I tried
wetting the cellulose with oil and methylene chloride, and added some
acetal ester. (Cellulose ester?) After giving it (not much) time to
soak in, I put it into a test battery. It was marginally
Then I started looking
up "cellulose acetate". It is or was used for a number of
things, including aircraft fabric dope, photographic film and fabrics.
Of course, the aircraft dope is gone (though related dopes are still
used for model aircraft) and buying it in some such finished form as
film or fabric is likely to be counterproductive. That leaves buying
it and dissolving it in acetone to make some sort of dope... or making
it. Ugh! So I looked up how that might be accomplished.
"Cellulose is treated with acetic acid and
acetic anhydride to produce cellulose acetate. Cellulose
acetate dissolved in acetone can be cast to form a film or extruded
through a spinneret to form fibers."
Acetic acid is vinegar. Unless
regular grocery store vinegar is too dilute (5%) to work right, that part is
"Acetic Anhydride is a clear, colorless liquid with a very
pungent, penetrating, vinegar-like odor that combines with water to
form acetic acid. It is soluble in ether, chloroform and benzene. It
reacts with alcohols.
"Acetaldehyde is converted into acetic anhydride by
atmospheric oxidizing the liquid acetaldehyde in the
presence of a metal acetate as the catalyst (Oxidation
Acetaldehyde we's got, but
now we need some other acetate to make the desired acetate! Great!
There was another way to make it, but it looked much
"The acyl groups (RCO) in organic anhydrides favor wide range of
"They react with water to give carboxylic acids, with alcohols or
phenols to give esters, and with ammonia and amines to give amides.
Acetic anhydride is used in the manufacture of cellulose
If pure cellulose acetate plastic can be had anywhere, it should
dissolve in acetone to make a "dope". I'm not betting on finding it.
I looked for cellulose acetate model aircraft dope on the
web and at BC Shaver shop, but no luck. They've switched to more
Here are a few
details I've decided on for the first Electric Hubcap workshop course.
I have a feeling I won't be able to start it in May the way things have
been going, but we'll see -- things just might develop rapidly.
Class size will be
limited to four particpants, who each have at least some experience
with fabricating and installing things. Classes and workshops will be
held at 820 Dunsmuir Road, which is not without some facilities for
the purpose. Hopefully it will be spring or summer weather for the
vehicle installations. Sessions will continue until the installations
are done -- I won't be pushing things. Days and times are TBA. (I
suspect Saturdays may be best for the most people - feedback
I will probably hold
more than one workshop series, but I think the first one will be the
most exciting one for all. After all, it will be the only first
one, a sort of beginning of a new age of automotive transport, and
while the basics are covered, there will be more opportunity for
exploration and discovery of more suitable techniques, materials and
implementations. Improvements will of course make their way into the
instruction maanuals on the web, and will set standards for future
more "cut and dried" workshop-courses.
The course fee
(assuming one typical motor) will be $2750. A $1350 deposit will be
required so I can buy the necessary materials. This will be
non-refundable once I've started purchasing things. (But you are
welcome to sell your spot in the class to someone else if you change
your mind about attending after paying the deposit - as long as I'm
not out of pocket I'm happy.)
Roughly the first
$1300 pays for all materials except batteries and battery chargers,
and the remaining $1450 or so is my take for preparing course manuals,
locating and buying the materials in advance, instruction time, and
for having invented it and worked out the details and circuit board
designs and layouts, which occupied me much of the past
If you wish to do a
project other than one 10.5" diameter motor on a car wheel,
please let me know and we'll make adjustments to the parts cost
portion of the fee. (Note that a small metal lathe is on hand if a
custom axle or other such part is needed. Lathe work isn't required
for the standard automotive motor.)
The driver's controls
will consist of a gas pedal position rheostat and a
forward-off-reverse drive switch. These feed the electronic motor
controller that has all the essential circuitry to safely run the
motor. A voltmeter mounted on the dash will be an asset to monitor the
state of the 36 volt batteries.
In the coming months I
plan to also make and program an improved microcontroller based
control board that will add limited regenerative braking, battery
charge while driving on gas, and a driver display (select: voltage,
amps, speed, motor temperature...). This will be provided free to
"alumni" when it's ready.
braking will be limited only because the motor is only on one wheel,
and so will pull the vehicle to one side. Only a small amount of that
Better batteries for
electric propulsion will be the subject (and product) of future
You can see the
estimated costs of the parts in the list below. Anything you wish to
provide yourself can be deducted from the deposit (or from the fee as
long as I haven't ordered it yet).
If you want me to
provide ready-made coils, wiring box, motor controller (or, eg, just
solder the components on the PCB thereof) or other components rather
than make them yourself, I'll do them for extra charges.
I do plan to make
these sorts of items available (maybe even a whole kit) when parts
$value * Description
230 * Rotors &
Hub/Axle/Bearings (show me your vehicle in advance to see what fits,
or supply yourself for 230$ discount - you may do well at an auto
wrecker. Tip: Firebird hub/axles remove easily with large torx wrench,
4 bolts. Others: check for possible 2nd set of (inaccessable) bolts from back
10 * Wheel extension
20 * .5" x 1"
square tube for stator arms
10 * Steel bar
5 * PVC Cover
12 * Misc.
75 * Magnet wire for
15 * Iron for coil cores (1"
nail gun finishing nail strips)
3 * Insulating spray
3 * Motor
5 * Hi-temp coil
20 * Misc hardware
* AWG#8 leads
20 * Optics PCB &
11 * 5-pin, 2 pin
"trailer" plugs & sockets
2 * Temperature
5 * Rotating slot
80 * 12 - 1" x 2" x
3 * Epoxy Steel magnet
20 * Aluminum Box pieces,
5 * Heat dissipation
fins (Alum. flashing pcs.)
40 * Battery
12 * AWG#6 or #8 'cab tire'
cable to motor
4 * misc heavy wire
7 * Copper to make
heavy wire terminal blocks (why cant you buy these?)
30 * Main Power
100 * Power contactor
"solenoid" (12v coil, continuous duty, from Ign.
36 * 3 - 7uF filter
capacitors (motor "run" cap.s, non polar)
3 * 3 - filter
6 * Aluminum mounting
8 * Aluminum transistor/heat
40 * 12 - IRFP3206 60v 120a power
6 * 6 - 40A automotive fuses
& solder lugs
6 * 6 - 100uF/100v filter
* Misc connection wire
60 * Motor controller PCB,
electronic components & plug-in sockets
* Misc bolts &
24 * Gas Pedal
5 * Fwd/Off/Rev
220 * Cab Heater / windshield
defogger (500W, 36V "golf cart" fan-heater)
15 * #10 cable for
100? * Brake electrical vacuum
25 * Battery state-of charge
indicator (for 36v Pb-acid batteries, "golf
Parts NOT Supplied
* Batteries (Six 12 volt, "size 27", 50 pound, "deep cycle" batteries are
around $600. Or, six 6 volt "golf cart" batteries are around
$900, and they evidently last better and will take you farther on a
charge. You might get a quantity discount, especially if 2 or
more people go in together. "Factory seconds" of "size
27", if available, are around $50 - $300 for 6. Shop around!
Three 12V "27" batteries will work, but the driving range
will not be very impressive. If you can find Ni-Cd or Ni-Mh at
economic prices, they should be better than Pb-acid. Personally I
wouldn't touch lithium, but who knows?)
* 36 volt Battery charger
* Outlet timer to turn off charger
* If there's anything not mentioned anywhere, please ask!
(Naturally, I hope to have the smaller, lighter, new chemistry
"Turquoise Batteries" ASAP, but something is needed in the meantime!)