Go Kart Project. Any Electrical Engineers?

[mpshizzle]

I'm working on a go-kart project and have reached a bit of a standstill limited by my knowledge.. any electrical engineers or anyone smarter than me willing to give advice?

So the basic idea is I am using an old treadmill motor to power a go-kart. It is a 130v DC motor. The power source is a 12v deep cycle battery. I have a variable voltage Transformer that will supply up to 97v.

I had two ideas for controlling motor speed
1) replace the potentiometer on the Transformer that sets output voltage with a digital potentiometer (controlled by Arduino).
2) constantly run the power supply at full voltage, and use PWM in line after the transformer.

Are either of these feasible or good ideas to get enough torque when starting, and not destroy the components?

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[Mach-Lee]

So a couple things. One is that transformers only work with AC, not DC. So in order to boost DC voltage it has to be converted to AC at some point. What you need is a boost converter, I'm not sure if the transformer you are referring to actually boosts DC or not.

Second is voltage considerations. You want your batteries to be about the same voltage as your motor if possible for efficiency. Going from 12V to 130V is a huge increase that will be really inefficient and will require a lot bigger boost converter. A 48V system would be much better.

Honestly I think you would be much better off starting with a 12 or 24V DC motor such as out of a power wheelchair, the 130V motor is going to add more complication to get working in this application.

If you must, I'd probably go the route of using a 120V inverter with some kind of AC to DC motor controller. Using the original treadmill motor control board and figuring out how to externally control it would be easiest.

Finally, a treadmill motor might only have a moderate amount of torque, I think this will mean the go-kart will be relatively slow (like a power wheels) or take a long time to build up speed. If you gear it so it goes 10 mph at max speed it might be acceptable, not sure how much speed or power you're looking for (kid toy or adult toy?).

 

[mpshizzle]

So a couple things. One is that transformers only work with AC, not DC. So in order to boost DC voltage it has to be converted to AC at some point. What you need is a boost converter, I'm not sure if the transformer you are referring to actually boosts DC or not.

Second is voltage considerations. You want your batteries to be about the same voltage as your motor if possible for efficiency. Going from 12V to 130V is a huge increase that will be really inefficient and will require a lot bigger boost converter. A 48V system would be much better.

Honestly I think you would be much better off starting with a 12 or 24V DC motor such as out of a power wheelchair, the 130V motor is going to add more complication to get working in this application.

If you must, I'd probably go the route of using a 120V inverter with some kind of AC to DC motor controller. Using the original treadmill motor control board and figuring out how to externally control it would be easiest.

Yeah I'm sure I used the wrong terminology there. It's probably not a transformer. It's a DC to DC...... Thing that will boost voltage ?

This is what I have:
https://www.amazon.com/dp/B07TJGZWJ...abc_G7V10DEKBP43HTFQ0GA0?_encoding=UTF8&psc=1

Hmm ok good to know. I am hoping to avoid buying a different motor so maybe I'll start with looking into getting an AC control board

 

[Mach-Lee]

Yeah I'm sure I used the wrong terminology there. It's probably not a transformer. It's a DC to DC...... Thing that will boost voltage ?

This is what I have:
https://www.amazon.com/dp/B07TJGZWJ...abc_G7V10DEKBP43HTFQ0GA0?_encoding=UTF8&psc=1

Hmm ok good to know. I am hoping to avoid buying a different motor so maybe I'll start with looking into getting an AC control board

30A X 12V = 360W max (current limited by the input in a booster). Seems way too small, I think the treadmill motors use 2-3x more power than that.

EDIT: I'll also add that those cheap China boosters get hotter than hell at their max rating, you should really try to keep them at 60% or less of max current for continuous use so they don't go up in smoke.

 

[mpshizzle]

30A X 12V = 360W max (current limited by the input in a booster). Seems way too small, I think the treadmill motors use 2-3x more power than that.

EDIT: I'll also add that those cheap China boosters get hotter than hell at their max rating, you should really try to keep them at 60% or less of max current for continuous use so they don't go up in smoke.

.... And this is why I ask people who are smarter than me! I was going off of the advertised 1500W number on that booster. Even if that's a realistic number I'd for sure max it out with that motor.

FWIW with my early testing it does seem to run the motor just fine (for short periods of time with no load on the motor ?)

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