Electric Launch, Electric Bike exsperiment... Basically I got bored one day.

I got to playing with the idea of building a small electric powered human ridden vehicle. A friend of mine gave me a Mountain bike. So I dug two Bosch GPA 750 watt  motors out of the storage shed and slapped together a mount for them. Since I had a Vantec RDFR 38E dual motor speed controller it should be very controllable. Hopefully!

The bike has two 12 VDC  Powersonic 18 amp hr batteries in series to provide 24 VDC to the Vantec speed controller that feeds the motors several hundred amps of sparks. A Hella switch is used to shut of the main 24 VDC power.

Of course this bike is still in early testing spaghetti wiring mode and I have to re-wire it for the real test, (moving my Large Mass down the road). Motor power is transmitted through a dual reduction both motors drive a single jack shaft. The jack shaft has a one way sprag clutch installed inside of it's input sprocket to allow the rider to peddle the bike without trying to turn the motors. The jack shaft then drives the rear wheel through a custom hub and sprocket mounted to the bikes spokes and hub. The final gear reduction at this time is 12-1. It should provide a maximum of about 192 Ft-lbs of torque at the rear axle at motor stall.

The bike weighs about 110 lbs at this point. Yikes it's heavy....

Brains borrowed from BOE BOT

Since this Vantec RDFR 38E controller was designed to read the servo command signals from an radio control model airplane receiver. It was necessary to create a PWM signal to talk to it. First I disabled the mixing function in the speed controller by changing it's internal jumpers. It now acts as two independent speed controllers. Since I needed a throttle I connected a 10k ohm variable resistor to a .01 uf capacitor and read the charge/discharge rate with a BASIC Stamp 2. Once I could read this value it was easy to output a PWM signal to each of the Vantec controllers inputs and "Bingo" the darn thing is humming like a Vantec should. Now all thats left to do is mount all of this stuff and go for a test ride...



Pbasic code for the BASIC Stamp 2
 

' {$STAMP BS2}
' {$PBASIC 2.5}
'DEBUG "Program Running!"

time VAR Word
DO
HIGH 7
PAUSE 10
RCTIME 7, 1, time ' read RC time constant using 10 pot and .o1 uf cap connected to pin 7
time = time */ 185 ' Scale by 0.724 (X 256 for */).
time = time + 500 ' Offset by 500.
IF time > 740 THEN time = 740 'prevent reverse rotation
DEBUG DEC time, CR 'display value for testing
PULSOUT 14, time ' Send pulse to speed controller.
PULSOUT 15, time ' Send pulse to speed controller.
LOOP



 
 

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