# Motor type efficiency



## Immo1282 (Jul 12, 2019)

Both AC and DC motors are reversible in direction - it depends on the controller used to do that, not the motor itself (though most DC controllers don't reverse)

Standard doctrine from what I've read round here on motors is;

DC: Cheaper, Unsophisticated power, cheaper controllers, Old tech. Brushes wear and need replacing periodically. No Regen & reverse uncommon.

AC: More expensive, more advanced controllers (expensive, more features). Regen braking (not for range really, but it's a nice-to-have). New manufactured AC motors are expensive and weak - Salvaged motors from OEM electric cars are usually less expensive and far more powerful. All motor advancements in tech are being made on AC motors now - OEM EV motors and controllers are the best way to go if budget's no object.


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## aquabiologist (Sep 8, 2017)

Immo1282 said:


> Both AC and DC motors are reversible in direction - it depends on the controller used to do that, not the motor itself (though most DC controllers don't reverse)
> 
> Standard doctrine from what I've read round here on motors is;
> 
> ...




Also, motor braking might be an essential feature, if you drive around mountains. Or have really, really good brakes.


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## trampintransit (Jan 5, 2020)

I have no real need for motor braking. Nor do I need much range or speed. The car is quite light ( probably less than a tonne without it's original engine ) If I leave the gearbox in...giving me 'mechanical ' reverse, then that simplifies the controller choice presumably...So is my best bet a simple DC motor? I'm seeing 3 phase motors...surely single phase is easier?


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## MattsAwesomeStuff (Aug 10, 2017)

> So is my best bet a simple DC motor?


For a low-budget, low-effort build, yep.

Used forklift motors for free-$200 are the usual plan.



> I'm seeing 3 phase motors...surely single phase is easier?


Nope. Single phase is a bit of a hack, motor-wise. You have to fake a second phase just to get it rotate.

3 phase is what everything is.

I don't know if I've ever even seen a 1ph EV conversion.


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## trampintransit (Jan 5, 2020)

Thanks for that ...I'm not clear on how that works coming from a battery supply. Can you point to anywhere where's circuit diagrams of how a 3p DC motor wires up to it's batteries?


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## Emyr (Oct 27, 2016)

The battery is connected to an inverter which applies + and - in turn to 2 of the 3 phases.


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## Zootalaws (Feb 23, 2011)

MattsAwesomeStuff said:


> For a low-budget, low-effort build, yep.
> 
> Used forklift motors for free-$200 are the usual plan.
> 
> ...


No such thing as ‘phase’ with DC. 

AC requires 3 phase, or some form of starter to get it to turn if single phase.


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## Emyr (Oct 27, 2016)

There are still 2 phases in a DC motor, but the commutation is mechanical rather than electronic.


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