Firefly Electric Conversion

[Stubby79]

Welded up the last mount as a test for the welder. Went really well. A bit of spatter, but not too outrageous. I am quite happy with it, even without shielding gas.

So, I re-wired it for 208v (so nice to have a high enough quality welder that you can actually do that), and made it a home. Unfortunately, it wouldn't fit on my undersized/cheapy welding cart with the handle on, but I don't see me packing it up to use it elsewhere, so I'll live with it off for now.

Here she is...


Ain't it cute?

I suppose I should have taken a pic of the weld/mount. Appears I have my priorities backwards!

[Stubby79]

Finally stuffed that motor mount in this morning. Finished it up a good week ago...think I was dreading it not working out or some such.



It was originally intended on having a flat plate at the mount end, and bolting up to the stock motor mount the same way it would on the ICE, but when mucking around to fit, i noticed it lined up very well this way, so I went with it.

Ain't pretty, but it's very functional. I have easy access to the shaft. The front, side, back and bottom have completely clear access to the shaft, it's only the top that has anything in the way...and it's pretty open, as you can see.

The "plate" that bolts to the motor is an 8" square made out of 2" flat bar, and the three horizontal chunks are 1x2". It's pretty solid, in spite of only being attached to the top 2" of said square. Tested my welds when it was done, with a big hammer...

I'm glad it's in, and hopefully I don't have to pull any of it out again. I fired up the motor to test it, as I thought it was terribly loud inside the cabin last time I tested it, but either the strap holding it up was transmitting the noise, or else it was the sound of the slightly rusty brake rotors scraping against the brake pads, as in neutral it was nice and quiet.

Now I can start in on things I'm more interested in...the electrical side of things. Maybe I'll run jumper cables inside and take it for a spin down the driveway for ****s and giggles.

[WyrTwister]

Looking good . Please continue to keep us updated . :-)

God bless
Wyr

[Stubby79]

I Put down this project for a while. I'd expended as much effort and then some as I'd expected to get it to the running stage, so I let myself get distracted.

But. I've started up again as of today, ready for round 2.

So, my current dilemma: battery location(s).

Option #1: Stand all 48 upright under the rear seat, where the gas tank used to be.

Pros:
Low center of gravity.
Almost perfect width and length for entire battery pack.
All cells are together, nice and neat, in one place.
Easy wiring for chargers and such in spare tire well.
Battery can come out in one big piece with an engine hoist.

Cons:
Fair distance to run heavy wiring to controller.
Have to cut the chassis, as cells are too tall.
Rear seat will have to be modified to be flat on top.
Lose structural integrity where seat belt buckles mount.
Cells are now inside the vehicle with passengers.
Translation: Back seat looks normal, but is pretty much ornamental.

Option #2: Stuff all the cells under the hood.

Pros:
Short power cables to controller.
All cells safely out & away from passenger cabin.
Frees up gas tank space for whatever else.

Cons:
No uniformity to cell packs/cells have to go wherever they'll fit.
Damned tight cramming everything else under the hood with cells.
Weight distribution heavier in front.

Option # 3 A bit of #1, a bit of #2; half cells under hood, half cells in place of gas tank.

Pros:
Two equal voltage/capacity battery packs (important part of my plans).
Even/good weight distribution.
Cells in place of gas tank will fit on their sides with no structural changes to unibody. (build t, bolt it, done).
Cells under hood will occupy a nice uniform rectangle directly over top of motor.
Comfortable space under hood for controller and everything else.
Space in front of motor/trans free for future expansion.
I can build the under-hood pack ASAP and start working on other things right away, get testing sooner...build rear battery pack at leisure. Or change plans and put remaining cells in front of motor & trans.
Can run wires up through drain holes at bottom of seat pans for cell monitoring.
Good use of space available.

Cons:
Long power cables.
Can't access/see/check directly batteries without dropping whole pack.
Most likely requires fan-forced cooling of cells if rear battery pack is going to be splash proof.
Lose use of gas tank area for any other purpose.


I'm leaning towards #3 at the moment. (the heck with SLA's) If I change my mind, it's the most compatible with changing to either #1 or #2 because I won't have to completely rebuild one of my two equal battery packs. And it will get me to the test stage sooner then #1 would, with less effort.

Thoughts? Experiences?

[Stubby79]

Gas tank space...




Useable Dimensions: ~32" width, 17" front to back, 5.5" deep.

Big enough for either 2 rows of cells on side, 12 cells long, 30"x16"x4.5", or SLA's on side, similar dimensions & weight, except an inch taller.

Same kind of layout, but cells standing on end so it's 30"x8"x9" will fit comfortably along rad support/in front of motor & trans, so pretty good chances I'll be making a couple of 12-cell long packs, either way.


First 24-cell pack's tray being built:


Compression plates:


Cells fitted, plates on, straps in place:


Weighs 50kg. About at the limit of manageable by hand, should the need arise.

Can straps be too tight? Probably not, using gear clamps...my "affordable", removable option...

Cells operate as a single unit now, separate of tray:


Cardboard pack replica a pretty good fit:


Tray in approximate location:



Side note: Spare tire well would be a good fit for the same size 4x6 cell pack. Just needs an inch extra on either side to clear the top of the pack. But this is putting weight out past the rear axle, which I'd rather not do. But I will if it gains me something else important...ie space. It does have the benefit of making the cells easy to access (so does having them all under the hood).

Trying to get a half decent backup option squeezed in is the only reason I've not commit ed to having them all under the hood already.

[Stubby79]

[cRiPpLe_rOoStEr]

Originally Posted by Stubby79

Spare tire well would be a good fit for the same size 4x6 cell pack. Just needs an inch extra on either side to clear the top of the pack. But this is putting weight out past the rear axle, which I'd rather not do. But I will if it gains me something else important...ie space. It does have the benefit of making the cells easy to access (so does having them all under the hood).

Trying to get a half decent backup option squeezed in is the only reason I've not commit ed to having them all under the hood already.

Placing some of the batteries under the hood and others in the spare tire well might be good if you're willing to eventually fit a range-extender that would require some space under the hood and the fuel tank.

[Stubby79]

Originally Posted by cRiPpLe_rOoStEr

Placing some of the batteries under the hood and others in the spare tire well might be good if you're willing to eventually fit a range-extender that would require some space under the hood and the fuel tank.

I'll probably going to go with all of them under the hood for now, see what kind of range I get, what kind I need, and make modifications from there. I'm trying to implement a certain level of modularity, so I'm not having to cut things apart to make potential changes.

I expect the batteries will suffice for 98% of my driving. It's the other 2% I'm not completely sold on giving up on yet. We'll see.

[Stubby79]

Got a good deal on an already converted EV...an old and rusty RX7. Brought it home yesterday. Attacked it this morning.


...



Yoink!



Spoils.

Too bad I didn't get said deal a few years back...but oh well.

[Stubby79]

Looks like I need to update the thread a bit, as well as get off my butt and get back at it.

I've got the one battery pack in, in the tray shown a couple of posts back. I had brackets/steel set up to hold the 1000-amp controller, right up until I got the other EV that I took apart in the previous post; I've since decided the 500-amp controller from that is better matched to this motor, as the 1000-amp is better matched to the bigger motor pulled from that EV. So I had to pull out the bracket I had built for the one controller and made room for the other and it's heat sink. That was the last thing I did. Oh and plumbed in the Curtis pot box.

Considering how close I am to being able to test it, you'd think I'd have jumped all over it by now. Instead I've been chickening out on putting it together. I'll be banging my head against the wall if it's a total flop when I get it going...

Which reminds me, one more step needed before I can start wiring: gotta hook up the emergency disconnect "pull" to the breaker. Then I won't kill myself if anything goes wrong. Not accidentally anyway.

Hmm. This wasn't what I was going to talk about. Oh yeah. The smaller motor I have, the 7.25" sepex. I got around to testing it the other day for RPM vs field @ different voltages, like I did the 8" I put in the firefly. I needed to know what voltages it can handle for part of a related but different project(which I have way too many of). What little reading I had found on it had come up with 8000rpm @ 72v with 12v on the field. That wouldn't suffice for my needs, so, as I said, I tested it myself.

I was please with the results. Its ~10% smaller than my 8" Sepex, and...it runs approximately 10% faster. Not even. More like 7 or 8%. That's great. That means it's running right at 5000rpm at 72v. That's in the useful range for what I need. It's what I originally expected, until I hand read otherwise...but my own findings settled things. I'm happy with the results.

I'm not sure just how fast it can safely spin, but I'll go with the usual numbers of 5000 or 5500 rpm as continuous, with peak/burst speeds of 8000. Might kill it going that fast. Depends if Advanced DC builds all their armatures equally. I hope not to find out the hard way that they don't.