DIY electric bike motor?
Monday, September 21st, 2009 at
7:26 pm
hey, im working on making my regular bike frame to hold a electric motor and battery, im not spending much on it, i got the 3/4 HP motor for free and a 12v 300CCA as well… my dilemma is that i only got to motor to work once, and i was using a regular AC outlet on a house. the motor is rated at 115v and as far as i know it runs on AC, it doesnt specify and i havnt gotten dc current up to 115v yet. is there any way on puting something like a transformer that will jump the 12v to 115v.
or maybe another cheap battery solution that will get me 115v. also how am i going to know if the motor just runs on AC. thanks, sorry if its vague, just ask for more info if you need any
try a power inverter like you plug into your cigarette lighter to run 115v appliances should find at most home improvement stores or Radio shack
to make your motor (120 volt ac) work from a 12 volt dc battery you will have to invest in a power inverter. These convert 12 volts dc to a usable 120 volts dc through the process of high speed electronic switching withing the unit. The only problem is to make sure it puts out a true ac current a the pulsed wave type will burn your motor up in short order. So be carefull and ride safe.
Your current motor only runs on AC. For this equipment, you will need a power inverter. This will change 12vdc to 115vac. And yes, you have to be concerned about the type of output that comes from the inverter. As another answer mentioned some devices don’t like inverters because they don’t put out a true sine wave.
But there are other concerns. A typical Capacitor Start Induction Motor will have a running wattage requirement of 1400 watts not to speak of the starting amp requirement of 3100 watts. Watts = amps x volts so at 115 volts your motor will require 1400/115 = 12.17 amps. Your inverter will be required to sustain this kind of output to run the motor.
While I would like to cheer you on with your project, you did mention that you are trying to do it on the cheap with a couple of free parts. One online store listed an inverter with this capacity as costing around $239 (1) with the pure sine wave model going for $450. Another listed a "no frills" model at $199 (2.)
There are several companies that make motors tailored for bicycles, recumbents and velomobiles (3.) They usually are in the range of 200 to 1000 watts and are 24 or 36 volts. Many are hub motors that will allow regenerative braking. The cost can also vary quite a bit but are expensive depending upon your budget. Good luck with your project. I would love to hear how you continued.
Why don’t you just go to a scrap yard and get a 12 volt DC starter motor. That will solve all of your cost problems. Use the "kiss" method, i.e., Keep it simple silly.
Good luck and have fun.