Geo Metro plug-in parallel hybrid EV - in progress

[Coyote X]

So what kind of amps would you guess I probably need to pull away from a stop light and accelerate at a average or slightly below average rate up to say 30mph? I can't find a lot of PMAC motor controllers that go much beyond 250 for peak amps. I am not sure how many miles a brushed dc motor can handle between rebuilds if I go that route. I typically put 15k miles a year on the car so I would like to have it last at least a year between having to mess with it.

The good thing about how the car is built if I need to I can move the passenger side firewall back to give me enough room to fit the motor up behind the engine. It won't affect the strength of the chassis.

[MetroMPG]

Good person to ask would be one of the Citi/Comutacar owners (yes, I know Ben owns one of those too, but hasn't really be driving it yet). They're fixed gear vehicles.

250A will give you less than "normal" acceleration.

When we had the 225A controler in the ForkenSwift, I measured 36 seconds to get to 30 mph - on a fresh charge, on level ground. And that's using 3 or 4 gears to keep the pot boiling just right. That'll get you honked at etc., in most places if traffic can't go around you. (The 400A controller is good for around 25 seconds to 30 mph.)

But Mike D claims acceptable acceleration from his fixed-gear e-5th wheel using a 275A Curtis & Etek PM brushed DC motor: Finding The Best Hybrid Mix - MIMA Honda Insight Modified Integrated Motor Assist Tour De Sol

If you go with a brushed DC motor... sprag clutch!

[bennelson]

That's right Darin, I don't even have a working ammeter on the Citi yet.

You all might want to check my acceleration test videos in the Metro.

Those show me accelerating away from a stop in the Metro in different gears. I am using a 400 amp controller on the car, and it pretty much tops out in that type of situation.

See it here:

http://www.youtube.com/watch?v=qSbPN_HaFHI

[MetroMPG]

Rick's likely looking at a 48v setup. Keep in mind your 400A @ 72v = 600A @ 48v.

[Coyote X]

I have nothing wrong with going higher voltage. The main thing I was looking at was the biggest PMAC controller I could find was 48V at 250 amps max. I like the regen and less maintenance that combo listed gives me.

So what about if I doubled the motors up and ran 2 of them at 250 amps each? That is getting expensive at 3000 bucks for the pair but if that is basically my main problem then that still keeps me within my more or less arbitrary $5000 budget I picked.

I did move my spare metro up to my garage today so this week if I have time I will take a lot of the body and extra crap off it so I can start figuring out where to put the motor. I might have room to put two motors or not really have enough room for one. I will find out soon I guess

[Coyote X]

I guess I am getting better search terms figured out for this ev stuff how about this controller:
Kelly Controllers KBL72301 max 300A Continuous 150A Voltage 72V

[bennelson]

That controller doesn't look too bad.

I havent' heard a ton about Kelly controllers yet, but I haven't heard anything bad about them either.

I suppose the rule of thumb is to get as many amps and highest volts you can afford.

I think that controller would suffice for you.

Doubling up motors and controllers would get complicated and expensive.

Jim Husted of Hi-Torque Electric has been building some "Siamese" motors with great success, but that's kinda a wacky drag racing thing.

[Coyote X]

So the weather looks like it is finally getting better, it was below freezing most of the time for the last few weeks. The longer term forecast seems more reasonable so now it is time to actually start doing something with this idea. I figure the first step is to buy a motor and mounting bracket and get it hooked up.

I still can't find a better looking motor for what I want out of it than that AC Etek motor. It should be able to handle 5000RPM easily so that gives me a 1.3:1 ratio to let the car get to 70mph without overspinning the motor and without a clutch on it. What I need to do now is print out a copy of that bracket on robot marketplace and tape up a cardboard model of the motor and bracket and see how it fits under the hood.

If it fits without making much of a bump in the hood then next step is to figure out how to get a sprocket on the axle. Anyone ever taken a cv axle apart and still able to put it back together? I am thinking that my best bet would be to find a drive hub off a motorcycle that is about the right size to slip over the axle shaft and weld it solid. That way I can change sprockets easily as they wear. I would like to use a pretty good chain so maybe something like a 525 O-ring chain would be best. I am not sure what it actually needs though so maybe something smaller or bigger?

I planned on using AGM batteries of some sort. Is there anything out there better than that but still being reasonably close to the same price? I looked around but it looks like they are still the best price/performance ratio out there. I need to also make a box up the same size as a battery and start trying to figure out where to cram 6 of them without taking up the last bit of space I have in the trunk

Other than getting a sprocket on the axle this really doesn't seem up front to be a hard project. Just expensive

[Coyote X]

Looks like it will fit

Just have to move the MSD box and fuse box somewhere else and there is tons of room. If it is mounted exactly like shown in those pictures it will have 2-3 inches of room around it. I will probably move it closer to the strut tower but I really need the motor and other hardware before I can know for sure where it is going to mount exactly. I took one of the old axles I had laying around apart and if I can find a hub that slides up on it then adding a gear will be easy. The total movement of the axle where I plan on mounting the gear is less than an inch so that is well within the range a good chain and sprockets can handle.

Looks like it is time to buy parts now. I wonder how long it takes that Robot Marketplace store to ship stuff out. I will probably order a motor and the bracket to start with since I have no idea what it is going to take to mount something on the axle.

[MetroMPG]

This is going to be lots of fun.

Glad the nice weather's coming back where you are, Rick.