# Help Me Find a Good DC Motor



## Emyr (Oct 27, 2016)

I googled the part number 8679773. That matches the ESAB EH-10A wire feed motor, which looks like the right model.

This product uses one EH-10A motor:
http://manuals.chudov.com/Digimig-Wire-Feeder.pdf
Note the supply: 115v single phase 7A.

7 amps x 115 volts = 805 watts.

You should be able to move a golf buggy or gokart, but you'll barely be able to make your RX8 crawl.


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## J_D (Feb 17, 2019)

Thanks so much for your reply

Forgive me If I'm getting confused here, I thought the bigger the motor voltage the more powerful the motor is?

What spec should I be looking for?

Thanks again for your knowledge

Jon 

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## Emyr (Oct 27, 2016)

Voltage and current are both pretty much arbitrary in isolation.

Higher voltage means needing better insulation and sturdier contacts. Higher current means your wiring has to be thicker to minimize resistance.

Most DC motors repurposed for EV use are at least 9 inches in diameter.


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## Duncan (Dec 8, 2008)

Hi J-D

You need to read the thread on using a forklift motor - I know it's long but skim your way through

Very short summary 
For a car you will need a 9 inch or 11 inch diameter motor
It will weigh between 60 kg and 100 kg

Most will be 36 or 48 volts - and rated at between 6 and 12 kW

You will need to operate them at above 140 volts


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## J_D (Feb 17, 2019)

Thanks so much for your replies, this is very useful information.

Yes I did see the forklift motor thread but like you say it's very long winded and I started to confuse my self.

Would you guys recommend series wound or direct magnet motors?

Thanks again

Jon



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## brian_ (Feb 7, 2017)

J_D said:


> Would you guys recommend series wound or direct magnet motors?


What do you mean by "direct magnet"? If you mean "permanent magnet"... when people refer to "forklift" motors they generally mean series-field brushed DC motors. There are many brushed DC motors with permanent magnet stators, but likely none available which are large enough to use to drive a car.


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## J_D (Feb 17, 2019)

Hi Brian

Sorry my bad, yes I meant permanent magnet motor.

I see, so series wound is probably my best bet.

I've found this on eBay, looks like the right kind of motor for the job, although it is missing the spline shaft.

https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/132980493451


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## Emyr (Oct 27, 2016)

The 1900rpm motor speed may require an expensive solution.

Your max wheel speed is likely to be about 1000rpm, depending on your tyre size and max vehicle speed. Most rear differentials have about 3:1 to 5:1 ratio and you'll need to add some other gearing to raise the propshaft speed above the motor speed, or be satisfied with a 50km/h top speed.


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## major (Apr 4, 2008)

Hi,

The RPM/speed is solved by running higher voltage. That's something you'd likely want to do anyway to increase power.

That looks like a fine motor and would likely serve you well, but...... It appears to be the hydraulic pump drive motor. Therefore two big obstacles for use in conversions. It is unidirectional. Right for you? It has an internal splined shaft. A bitch to couple.

Regards,

major


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## J_D (Feb 17, 2019)

Hi Major

Thanks for your reply 

So to increase voltage to attain maximum speed, am I assuming I'd have to increase my system voltage?

For instance 14x 12v batteries in series to make 160v ?

Ps could buy a spline shaft I guess

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