Firefly Electric Conversion

[cRiPpLe_rOoStEr]

Originally Posted by Stubby79

Still figuring out what I'll be doing about a vacuum pump and a real charger, but I have time for that while I work on the rest.

Have you never even considered to eliminate the vacuum booster?

[Stubby79]

Originally Posted by thingstodo

So what voltage are you running? Since you already have the pack ..

I have 52 cells, 48 meant for the traction pack and 4 spares (meant in the meantime for the 12v accessories.) Since the controller will take it, I will presumably run them in a single string @ 153.6v, though I expect while I'm testing things out, I'll run 2px24s for half that. I bought them with the intention of being able to re-arrange them for higher voltage if I ever got my hands on a decent controller.

What have you fused the controller at? Do you have a part number on the fuse? I messed that part up and am looking for examples

It's not currently fused, since it's not currently installed. I've got 2x 250a/250V DC breakers on the way from the same seller who sold me the controller. Hopefully I'll only need one @153v, with a light car and a small pack.

Originally Posted by EVmetro

It is great to see another Metro conversion in the works. I have converted several Metros and really like this choice of chassis. It was the king of mpg when it was an ICE, and it will be the king of miles per kW as an EV.

Thanks. I wondered when you would chime in! Your build threads on GMF are helpful for planning things, and when that wasn't enough, your photobucket has some additional useful shots. I particularly like your use of all the available spaces in a Metro to hide things.

Just don't expect me to have your level of patience and attention to detail!

Originally Posted by cRiPpLe_rOoStEr

Have you never even considered to eliminate the vacuum booster?

Sure, when I was originally planning on having regen brakes, it seemed a moot point. I doubt I can do without one or the other, though.

[cRiPpLe_rOoStEr]

Even if you wouldn't get regenerative brakes, a vacuum booster still seems kinda overkill for such a small car. And an electric vacuum pump would be sucking some precious kWh...

[Stubby79]

Originally Posted by cRiPpLe_rOoStEr

Even if you wouldn't get regenerative brakes, a vacuum booster still seems kinda overkill for such a small car. And an electric vacuum pump would be sucking some precious kWh...

While I agree that kWh are precious, I'm not concerned about a vacuum pump wasting them. Unless you're running a big vacuum pump constantly (which there is no need to do either), you'd be measuring in "mere" watt-hours. The pumps I've been eying use maybe 1 amp at 12 volts, and it would be lucky to run for 5 minutes total per typical trip, at a guess.

What doesn't seem so easy to find is an affordable vacuum switch, which would make this particular task a lost simpler.

[Stubby79]

A bit of progress this morning:



Took the exhaust off. Had to cut the muffler off, unfortunately. Oh well. It's still salvageable, if I ever need it.

Then I did some hot-wiring:



...putting power straight to the fuel pump. Nice of them to put the relay right under the hood instead of up under the dash or somewhere else annoying!

I had some 1/4" fuel hose hanging around from another project, so I put it to use.

The PO wasn't lying when he said it had a full tank of gas. Filled up the wife's car (was just over half filled), filled up my '95 Metro (also just over half a tank in it before I started), then had to go fetch my 2.5-gallon jerry-can and almost filled that up before it finally started spitting air out. Should be a lot easier to drop the tank now!

I'll hopefully get around to that tomorrow morn. Think I've had enough for today. Certainly enough gas fumes! I'll go fetch some engine enamel in what spare time I have left today.

Keep plodding along...

[Stubby79]

Looking for opinions/confirmation on my choice between the two motors.

My intended use of the car is my 15 km trip to work every day. For a good 5 minutes of said drive, I'm on the highway. Most of it is flat, but, unfortunately, the last 2km is one long hill, which I estimate at a 5 or 6% gradient. I should be pulling between 22 and 26 kw to climb a 6% gradient at 90 to 100km/hr.

I'm assuming that thanks to this hill, the 8"/larger motor would be the better choice for this project.

On the other hand, Mechman600 was occasionally putting 30kw through the smaller motor, and it doesn't appear to have bothered it much.

The body on the 8" is about 3/4" shorter then the 7", and will just barely fit. (And, as it is, the secondary shaft will be sticking out underneath the frame rail. Hopefully it won't be in the way. Not happy about losing the usefulness of said shaft. I could really use the 4 cylinder mounts and cv shafts!). The 7" could possibly be modified to fit better.

I should probably stick to the 8" until I come up with a better use for it. Wouldn't be hard to pull it out again...

Someone confirm my assumption that I should be using the 8", so I can stop wondering if I'm over-doing it!

[Daox]

The 8" will give you more torque at lower rpms. I'd go with it.

[thingstodo]

Originally Posted by Stubby79

Looking for opinions/confirmation on my choice between the two motors.

Sorry for my qualification on this one - I did not look up the gearing ratios for the Firefly transmission

Assuming 5 speed manual gearbox, if you can climb the hill in 4rth gear (or better yet in 3rd gear) without going overspeed on your motor, the 7 inch will. IMHO, work fine.

Of course, the 8 inch is bigger, likely higher torque output, will take longer to heat up, etc. So you have a bit of a safety factor.

But the 8 inch is heavier so you have a heavier car .. all things being equal you choose the lowest weight option, right?

I don't think you will overheat your 7 inch motor on this trip. I have hauled a trailer with a 48V DC club car (800 lbs with leadies) for a few minutes .. maybe 5? .. with the motor amps at 200+. It was a not-so-quick walk. The motor had NO air cooling since it was turning so slowly. The DC motor is a bit smaller than 7 inches, maybe 6.5 inches, single speed gearbox. The motor was hot to the touch, but you could leave you hand on it without getting a burn.

My point is that you will be doing about 180 amps for the hill at 156V for less than 5 minutes .. that should not cook your motor. The club car was not putting out the same power, but it was taking similar amps, which is where you get the heat from

[EVmetro]

I would go with the 8.

As light as this car is, and as light as a 10kWh pack is, You could probably live without the brake booster. I run with my brake booster vacuum pumps turned off most of the time on my various electric Metros. The booster is nice, but an 8 inch motor and 10kwH pack in a Metro, it is pretty easy to stop with no booster.

[Stubby79]

Thanks for the input!