I am looking for input on a low-budget build I am considering.
I am using input from a few other threads, including:
Multiple small motors
I would like to combine these 2 concepts in to an effective, yet practical approach for those on a limited budget. I plan on using my VW bug as a test platform, assuming this proves to be practical. For the motors, I am considering using several (number yet to be determined) starter motors. The quick specs of the motors are 12V, 1HP. Now, I want to be clear that I know the draw backs of using smaller motors and that these are not ideal motors. I also know that these motors are made to be run a short amount of time, so part of the plan is to cool them.
I am thinking of a gear on the transaxle shaft (not the large flywheel gear) and these starter motors mounted around this gear with gears of their own. To cool them, I would either use an electric fan or a fan driven by the input shaft of the transaxle (so the cooling was proportional to the speed of the motors). the electric fan would have less drag on the system so would probably be the best bet. I would use a large fan shroud to focus the air on the motor system and draw it in through the fresh air intake at the top of the engine compartment.
For the controller, I really like the idea of a mechanical PWM. I am aware of the limitations of this device, but I really like the fact that it is a serviceable part. With the electronic controller, sure you have more efficiency, but you never know if/when it will decide to leave you stranded. With a mechanical part, it could be serviced on the side of the road (to a limited capacity) and possibly get you back home. Also, the reduced cost would make it more that possible to carry a spare - something VW drivers are all to familiar with doing.
This is the design in its most basic form and I now ask for input to refine the concept and hopefully move into the fabrication phase. I have all the tools required (mill, lathe, welding equip, etc).