Hello! Advise (Electric Motor) on EV build!

[CarlosP]

Hello again! I was offered a Suzuki Swift pretty cheap, and decided that it would be the best choice for an EV build. Its the lightest car I could find.

I need some advise before I start jumping around and buying stuff.

What types of specs in an electric motor should I look for to achieve a car that might be able to go up to 50 mph or more and sustain it?

[Oval_Overload]

Check out the EV Album for other Swift/Metro/Firefly conversions
Anything north of 7 inches should do the job. For 50 MPH you'll want at least 96 volts nominal (resting) pack voltage. I've done 62 MPH (100kph) in a 3 phase AC Wheego Whip at 96 volts. It scooted to 50 mph just fine, but the last 12 mph were on the weak side; to sustain 60, one more battery would be advised.

Carlos, what is your budget? Are we talking salvage special or state-of-the-art? How long do you plan on "sustaining" 50 mph? Range is inversely proportional to speed. Also, on lead acid batteries, you will loose 1% of your range for every degree the battery pack is over or under 77ºF. If you're in a desert, cooling is advised. if on tundra, heating is needed.

Electric cars are fantastic, but you really need to know what you're getting into.

~Jim
EV mechanic,
Minneapolis, MN

[rgathright]

I like the NetGain series of electric motors.

For you the TransWarp 9 with integrated tailshaft should get you rollin with plenty of torque.

EV Source - NetGain TransWarP 9 Electric Motor

[Oval_Overload]

The Transwarp is for RWD. He needs a WarP 9 with a Swift/Metro/Firefly adapter plate, or a Solectria/Azure Dynamics gear reducer.

~Jim

[CarlosP]

Originally Posted by Oval_Overload

Check out the EV Album for other Swift/Metro/Firefly conversions
Anything north of 7 inches should do the job. For 50 MPH you'll want at least 96 volts nominal (resting) pack voltage. I've done 62 MPH (100kph) in a 3 phase AC Wheego Whip at 96 volts. It scooted to 50 mph just fine, but the last 12 mph were on the weak side; to sustain 60, one more battery would be advised.

Carlos, what is your budget? Are we talking salvage special or state-of-the-art? How long do you plan on "sustaining" 50 mph? Range is inversely proportional to speed. Also, on lead acid batteries, you will loose 1% of your range for every degree the battery pack is over or under 77ºF. If you're in a desert, cooling is advised. if on tundra, heating is needed.

Electric cars are fantastic, but you really need to know what you're getting into.

~Jim
EV mechanic,
Minneapolis, MN

The car would basically be used for city driving, mostly short range. I was hoping to salvage any electric motor that might get the car anywhere between 50 or 60 mph. The car will mostly be used at around 35mph for about 5 to 10 mile daily drive. It would probably got no further than a 20 to 30 mile drive maybe once or twice a month.

What would be the longest distance achievable at 50mph on a vehicle of this weight?

How many miles have you been able to run at 50mph on your setup?

I am a computer geek and know a bit of electronics, but when it comes to electric motors I have no clue. I've seen a few on eBay but there are 24v, 36v, etc.

How would I know which once is the right to achieve what I have in mind?

[CarlosP]

Trans Warp 9, Warp 9?? Hmmm.. I'll do some searching to read the specs..

[Oval_Overload]

No way in hell you're going to salvage a WarP series motor. My suggestion would be to steal one, whilst distracting the cashier with large sums of money.

As for voltage, the motors can be substantially over volted if adequate cooling is provided. Look for a Sep-Ex/Shunt wound motor if you can. With these, you can control the field coil separately from the from the armature, acting like a transmission. Turning the field current down gains you RPM at the expense of torque, like an overdrive gear.

In regards to vehicle range, that depends on the watt hour capacity of your traction pack. As a general rule of thumb, more voltage nets you more range and more speed. More coin nets you more voltage. My advice to you is to concentrate on three primary areas of your build and let the rest follow.

Motor
A used motor will work fine, but it has to be properly sized to the car and properly cooled. You state that you want to sustain 50 MPH. If you don't buy new motor, you'll probably have to find a used motor designed for use in an EV. Don't cheat yourself on power. You don't want to be that ass causing a traffic snarl at every stoplight.

12 VDC power supply
Sit on the floor pretzel style, close your eyes, and repeat after me... "Don't cheap out on the DC/DC... Don't cheap out on the DC/DC..." You can have the worlds best traction pack, but if your 12 VDC system conks out, you're hosed. Without 12 volts, you can't energize the contractors. Use a DC/DC converter, solar panels, whatever. just make sure it works.

Battery charger
It doesn't matter if you're running used UPS batteries or fancy lithium cells, a chincy charger is the quickest way to toast them.

~Jim

[CarlosP]

Hahaha.. Of course I'm not going to find a salvaged Warp9. I only wish.. as for stealing it.. hmmm.. tempting..

I was thinking that there was a chance of salvaging an engine from a forklift or other source that might yield some decent output. But if it wasn't possible, I would spend more on a better motor.

I want it to be an economical build, but I don't want to cheap out on vital parts that might cost me on the long run.

All input is greatly appreciated, so keep them coming!

[Oval_Overload]

If you cheap out on the DC/DC, it will cost you. I know a guy who has burned out so many cheap dc/dc units that they collectively have equalled the cost of one high quality unit.

Here is a gentleman in my state who is getting respectable numbers from a forklift motor in a Gen 1 Saturn SC (keep in mind this is a very light car. The body panels can be weighed in ounces :P )

He appears to have found a 72 VDC forklift motor. These are not easy to find, but I think you will be much better off if you take the time to look for one. Plus, with a 72 VDC motor, you can add cooling and over volt it to 84 or 96 VDC for a noticeable increase in power and range. This may require tweaking the brushes (do your homework).

Remember, to keep things economical you can build Paul's Open Revolt controller.

[Oval_Overload]

Opps
I forgot to post the link

Brian Darovic's 1994 Saturn SC2