I am trying to do an electric small motorcycle conversion. Since this round is more of a proof of concept than anything I want to keep the DC Motor cheap. After struggling to find a DC Motor with moderate power for a cheap enough price, I found out that older treadmills have a DC Motor that powers them. Most treadmills only have 0.5 horse power, but some have up to 5 hp. I want to run this motor off of a battery pack, but everything I see online says I would need to use an inverter first to generate ac current from the batteries to feed the treadmill.
My question has four parts, but the first two parts are the ones I’m most curious about.
1. Why do I need an inverter? If it is truly a DC Motor wouldn’t the current be rectified within the treadmil circuitry anyway?
2. If I took only the motor from the treadmill and provided my own dc operated PWM system, would it work? And if not why?
3. Is an inverter efficient with power? I don’t know much about how they work, but I do know that when it comes to an ev project power waste should be avoided almost as adamantly as being electrocuted.
4. Is a treadmill motor even a good idea for this project? I really don’t need it to be super fast, and all the treadmill motors say they are continuous duty. Is this the cheap solution I’ve been looking for, or is there a better place to salvage a DC Motor?
Answers & Comments
Verified answer
You need to just buy a kit like this:
https://www.amazon.com/dp/B00YBWAINC/_encoding=UTF...
Trying to convert a heavy treadmill motor that was never meant to be powered by battery just sets you up for an inefficient system that will give you barely 20 minutes of power.
1. If it's truely a DC motor you would not need an inverter. It would be difficult to find a treadmill that was DC unless you somehow knew the specific models that had DC motors. On top of that if the motor is DC the control board might be AC or at a different DC voltage than the motor.
2. Maybe, but dealing with the amperage requirements for that type of motor may be expensive and challenging.
3. Inverters are very inefficient as far as converting DC to AC.
Honestly you need to research electric bicycles which are much lighter and would have a much higher rate of success than trying to convert a motorcycle. Custom electric bicycles can go as fast as 30 mph. Your main challenge is the expense of the motor and more so the batteries. You can't go very far on an old car battery. You need multiple new batteries.
TREADMILL MOTOR IS AC MOTOR, NOT AS WHAT YOU THINK IS DC MOTOR.
While there are some good reasons a DC motor might be used in an old treadmill, it is almost certain that the motor would be fairly high voltage and need to be a fair number of amps with the DC being supplied by rectifying AC as you implying your question. Doing this from batteries guess to be expensive and heavy if you use lead acid batteries and doing it from a modern lightweight lithium battery pack which is almost certainly what you should be using gets very tricky to get to the higher voltage. To have something that works these days you need to understand the problems of recharging lithium batteries taking a good look at the information in people working on packs such is RC aircraft.
And focusing on the efficient motor instead of trying to go cheap is going to do a lot more for proof of concept than salvaging something old.