# inexpensive motor choices



## judebert (Apr 16, 2008)

Your performance and range requirements indicate that advanced batteries will likely be required. That pretty much puts the kibosh on "cheap".

Motors shouldn't be considered by themselves; they need to be considered along with their controllers and power requirements. For full-sized car traction applications, there are two popular options: series-wound brushed DC motors and AC induction motors.

Series-wound brushed DC motors (like the ADC, NetWarp, et al) and the controllers to run them are generally the cheapest combo available. They're also well-understood and well-tested. They provide outstanding acceleration and good efficiency. They work with inexpensive low-voltage packs. They generally don't provide "regenerative braking", which extends your range by generating electricity whenever the car is slowing down. The brushes need to be replaced occasionally; generally every 80,000 miles or so, depending on conditions. RPM limits almost always require a transmission.

AC induction motors (like those found at MetricMind) require more complex controllers, and generally must be matched. While the motor is cheap, the controller is rather expensive. ACIMs often require higher voltages and more expensive battery packs. Their performance is generally lower than their DC counterparts. There are fewer ACIM conversions, so they're slightly less well-supported. However, if you're willing to brave these difficulties, you get a more efficient system, often with regenerative capabilities, extending your range even farther. You never need to change brushes; in fact, the motors are sometimes submersible, and they never EVER break. They are generally rated for much higher RPMs than their DC counterparts, allowing for "direct-drive" through a differential, reducing vehicle weight and complexity.

Maybe next time I'll make a bulleted list.

Since you want 50 miles at 70MPH, you'll probably need lithium batteries anyway. That provides the opportunity for a high-voltage pack, which could be paired with an ACIM power plant for outstanding efficiency and range. Unfortunately, it's not going to be cheap. Check out MetricMind's website to get an idea of the cost.


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## tgrant11 (Jan 26, 2009)

I have read some past posts and it seems like forklift motors are an inexpensive way. I have found an online auction which has a few sit down styles that seem very reasonable. The place is 3.5 hours from me so it would be pretty hard to go just to look at them. Is there any way to tell if one has a motor that would work or not. 

1) Clark Electric Lift Truck, Hours 9031.7, Model ECS20, SN: E357-C435-0971FB, 36 Volts, Max. Capacity 4000 lbs., Elev. Height 75" with Side Shift Attachment Brudi PN: PMB4Z-34310031. Forks are 15" x 44", Runs

2) Caterpiller Electric Lift Truck, Model M40DSA, SN: 8AB00919, Type EE, 36 Volts, Max. Cap. 4000 lbs., Elev. Height 173" with Side Shift, Indicated Hours 7084. Forks included but not shown in photo. Runs

3) Clark Electric Fork Lift, Horse 7369.4, Model ECS20, SN: E357-0434 8971FB, 36 Volts, max Capacity 4000 Lbs., Elev. Height 75" with Side Shift Attachment, Brudi PN: 22343. Forks at 15' x 44", Runs.

It seems that at the speed and range that I want I will have to splurge for expensive batteries. I was wondering if I went with lead batteries what would you estimate I would have to give up in Speed,or range? 

On a third note, The auction closes today.


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## Bowser330 (Jun 15, 2008)

With the right gearing available most lead powered DIY EVs can reach up to 70mph (speed)..not very quickly though (acceleration)....

Range will suffer if compared to lithium (weight per AH), unless you load it with extra lead batteries, but dont worry about the extra weight since the low-end torque of the DC will get you moving...

Brake and suspension upgrades are recommended if you are going to exceed the OEM specs...


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## Qer (May 7, 2008)

tgrant11 said:


> It seems that at the speed and range that I want I will have to splurge for expensive batteries. I was wondering if I went with lead batteries what would you estimate I would have to give up in Speed,or range?


It's actually possible to get both if you don't mind loading the car with a serious amount of lead. Here's the extremest example (as I know of) when it comes to getting range with lead while still maintaining speed:

http://www.evalbum.com/037

However, it's not an entirely practical solution imo (and not even legal in Sweden, where I live). I have almost the same range need as you and with the added "bonus" of living in a cold climate (which complicates things with lead batteries) I've come to the conclusion that lead will be a bit too complicated and the risk of getting an EV that doesn't quite fill my needs (especially in the winter) has made me realise that it'll have to be Lithium.

It'll cost much more, yeah, on the other hand it means that even a minimum sized pack will be able to take me to work and back twice without charging and probably last much longer than a lead pack that will be more or less drained every day.

But as judebert said: That pretty much puts the kibosh on "cheap".


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## tgrant11 (Jan 26, 2009)

Thanks for the input! I have been looking for a motor and am still wondering if a 36 volt forklift motor would work well? I also have a chance to get a reasonable 48 volt but the place where I would buy it is a motor rebuilder and says they would recommend a motor designed for the extra voltage. I was under the assumption that it would be possible to get a 36 volt and advance it to accomidate the extra voltage. Can anyone enlighten me on what to look for???


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## DIYguy (Sep 18, 2008)

tgrant11 said:


> Thanks for the input! I have been looking for a motor and am still wondering if a 36 volt forklift motor would work well? I also have a chance to get a reasonable 48 volt but the place where I would buy it is a motor rebuilder and says they would recommend a motor designed for the extra voltage. I was under the assumption that it would be possible to get a 36 volt and advance it to accomidate the extra voltage. Can anyone enlighten me on what to look for???


I would suggest that you read the thread on lift truck motors, search out some candidates, take pics of them and note model numbers if available. Try to take of the bands and get pics of the brush/com area. Send them to Jim Husted of Hi-Torque Electric and hopefully get his opinion on which is best. This worked well for me. Mine was rated 36/48 volts. I don't know if there is much difference between the two voltage ratings or not.

"Major" is a good resource also with a lot of experience.

Cheers,
Gary


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## tgrant11 (Jan 26, 2009)

Thanks Gary


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