OwnerPaul Holmes
LocationOlympia, Washington United States map
Vehicle1971 Volkswagen Super Beetle
It was only $40, and you get what you pay
for. I had complete access to the
transmission from inside the car in the
back seat, which made it really easy to
work on. :)
MotorGeneral Electric Series Wound DC
It's about 60 pounds, and 6.7"
diameter. Really old. From Ebay. No
clear information on it, other than it
is rated for 24v, and 102 amps for 1
hour. I added a blower that blows
right on the brushes. It was getting a
little hot at 72v, but still not bad.
Now it stays really pretty cool.
Drivetrainit's clutchless.
ControllerOpen ReVolt None, just from my garage.
144v 500 amp controller.
So far it's working really well! Whoever
put that thing together did a really good
job! haha.
Batteries6 Sears DieHard Platinum edition, 12.00 Volt, Lead-Acid, AGM
100 amp*hrs and 75 pounds each.
System Voltage72 Volts
Charger home made
constant current constant voltage
charger. It talks to my battery
management system with CAN, so that is
how it CAN know what the voltage of the
pack is. It will charge anything up to
around 200v at around 30 amps. You
don't have to set the voltage. It just
makes the current constant for whatever
voltage you feel like hooking up to it.
It's made for lithium batteries.
HeaterHarbor Freight 12v heater. Worthless.
Instrumentation2 Harbor Freight volt meters
Top Speed40 MPH (64 KPH)
It can pretty easily reach 40 mph, in
about the same time that it takes to get
to 40 in a regular beetle.
Accelerationlike a regular Volkswagen Super Beetle.
Range20 Miles (32 Kilometers)
20 miles to a dead battery pack, driving
at around 30 mph.
Watt Hours/Mile320 Wh/Mile
I just want to say that W*hr/Mile is a
unit of force. I figured that out myself.
It's a measurement of how hard you have to
push the car!
EV Miles
Current:500 Miles (804 Kilometers)
Seating Capacity2 adults
Curb Weight2,200 Pounds (999 Kilograms)
Tires4 of them, and they are rubber. It's just
the kind of tire that when you go to the
store, and say you want tires for a
volkswagen super beetle, then they give
you those.
Conversion Time4 weeks or so
Conversion Cost$2200
Additional FeaturesI made a bms to talk to the charger. Basically, each box
monitors 8 batteries. The box doesn't have to be very
close to the batteries it manages. Each battery's
voltage is measured by an ATTiny, and then that attiny
sends the voltage by a sort of morse code to as
dspic30f4011 that is also in the box. So, the dspic is
constantly receiving voltages from 8 attinys. Then, the
dspic sends a CAN message to the charger about its 8

The shunting is about 2 amps per battery. I use 25w
chassis mount resistors, so I could shunt at a higher
current, but this works fine. The shunting happens by
pwm. The shunt pwm is at 50% duty, so that if a mosfet
failed, it would go to 100%, blowing a fuse, taking the
battery out of the circuit.

Now, I made this for lithium batteries, and I've tested
it on a string of 45 thundersky lithium cells, but that's
not what's in my car right now. I don't own the cells.

code by jerry