I am in the early brainstorming stages of my project in which i would like to modify a mountain bike to be powered by a small starter engine off of a 1975 ford F150. My original idea was to have a car battery powering the engine and using a dimming light switch in place of a throttle, however, as i think about it i realize how impractical a car battery would be due to the fact that there is no easy way to recharge it. I was wondering what other battery types i could use for the project. The approximate power draw of the starter motor is 150 amps at 12 volts. If anyone can help me find a solution it would be appreciated.

PS. I've been thinking about laptop batteries but am unable to find the exact maximum outputs of the average laptop battery.

 

A starter motor is an inefficient type motor to power your bike.

And what type of dimming light switch were you planning on using?
Standard dimming switches only work on AC, not DC.

Why can't you recharge a car battery?
You just need a standard car battery charger.

 

Up until right now actually I wasn't able to find a car battery charger that worked off of ac power, only generators, but I just found a good charger so I suppose I can use a car battery. I didn't know a dimmer switch only worked on AC as I'm quite new to this (if you have any suggestions on a different way to accomplish the same effect it would be greatly appreciated). Also I'm using a starter motor since they are very cheap and readily available despite being inefficient.

 

Running most automotive starter motors unloaded they will literally burn themselves up. I doubt that starter motor will draw even close to 150 amps pushing a bicycle along. While this is not my forte if I recall the basics the starter motor has a pinion gear which is tapered. That engages the flywheel and the gear ratio is something like 15:1 to 20:1 more or less. The auto cranking speed is around 200 RPM and the starter is delivering tremendous torque. I just do not see this as a good idea and speed control of an automotive starter motor will not be easy since a starter motor was never designed with speed control in mind. You would need a heck of a gear ratio just to slow the motor down. Thinking a bicycle tire rotating at 200 RPM would be awfully fast, even at 100 RPM you would be flying.

Just My Opinion, we have a forum member named tcmtech who is real good with stuff like this and hopefully he will see this thread.

Ron

 

This was more of a proof of concept/ why not project for me. Starter engines are very readily available so if it burns out, or I can't get a good gear ratio, I will look into another type of engine

 

Well proof of concept is always good for the learning curve. Since you just want proof of concept I would go ahead and use a car battery. Since you just want to know if this will work 12 Volts is 12 Volts.

Ron

 

I didn't know a dimmer switch only worked on AC as I'm quite new to this (if you have any suggestions on a different way to accomplish the same effect it would be greatly appreciated).

The usual way to control a DC motor is with a PWM (Pulse Width Modulation) controller such as one of these.
They efficiently control the speed without dissipating a lot of heat.
100A output should be more than sufficient for your purposes.