Firefly Electric Conversion

[Stubby79]

Rest of the cells are in!





that's a lot of voltage to be messing around with!

[Stubby79]

Took her on her maiden voyage...



A good 23 km, according to google. (Since I didn't note how many km on the odometer - oops!)

And used...



23 amp-hours.

...?! That's one heck of a coincidence.

Doing the math, that's 150 wh/km (241 wh/mile), assuming a steady battery voltage of 150v. Pretty easy math, as far as it goes! Anyway, that's actually about where it should be. Still one heck of a coincidence!

That puts my range at the ~50km I was aiming for.

We'll see exactly what it comes out to per km/mile once I have the chargers installed.

It wasn't without incident, mind you. My low-voltage "sensors" would occasionally go off under heavy, sustained load. So I have to determine if there are weak cells, or if it's the all too affordable "sensors". And there was a clunk under heavy acceleration...which is either the driver's side CV joint being out of alignment and/or too short, or else the drive-train was jerking up and down as I bounced off some limiter in the controller and banging against my battery racks.

Chargers, voltage drops and clunk are at the top of my list of to-do's.

Knocked these off the to-do list. Purely out of vanity and as an easy win:



Pretty good maiden voyage, all things considered!

[Stubby79]

Video dump:

https://www.youtube.com/watch?v=o3m43YL6_Cs

https://www.youtube.com/watch?v=ePiw-SXQGbw

https://www.youtube.com/watch?v=37pnVrs4aww

...of most of the trip.

1st vid is pretty boring. (for the hard core watcher)
2nd vid you get to see some decent scenery, and the first few seconds of getting on the highway. (long, a bit more interesting)
3rd video is right in the middle of driving along on the highway. (just watch this if you want to skip to the money shot)

[Stubby79]

Made myself a charger relocation cable out of 12/4 wire, so that I can put the chargers anywhere in/on the vehicle. This allowed me to do a rude setup in the trunk to get it charged back up...



Readout for the two "72v" chargers:


And with the accessory battery charger too:


Took some readings...main chargers are running at a hair over 90% efficiency.

Currently waiting on it to finish charging to get a final kWh reading...

[Stubby79]

That's quite the difference between wall-kW and battery kW! About 30% more!

Hmm... ~0.3 of that is the accessory battery. So actually about 25% more for just the traction pack.

~10% lost at the chargers. ~10% lost for battery charging efficiency. I suppose the other 5% could be accounted for by charging voltage ~156v+ vs the 150v approximate I was using.

Ok, nothing unusual going on here. But I'm dang glad the chargers are as efficient as they are, or this could get ugly!

Anyway, that puts me at ~2 cents per km electric, vs ~8 cents per km in my gas version.

Time to add a fuel log!

[Stubby79]

Trying to decide if I want the SLA's in the spare tire well, or underneath where the gas tank was. The chargers will go in whichever is free for them.

If the chargers are in the spare tire well, I'll have to add some forced cooling. If they're in place of the gas tank, I have to depend on their waterproofing to be effective, and I can't see the lights on them.

If the batteries are in the spare tire well, there will be more rearward bias than if they are in place of the gas tank. There's a lot of frontal bias with the second set half of the traction pack being in front of the front wheels; will having more rearward bias offset this, or will it be too much and screw up the handling/stability in corners?

Well, I don't have time/energy to install anything in place of the gas tank today anyway...I think I'll finish turning the trunk in to a "work-in-progress" area that holds all the SLA batteries and the chargers. (And I'll see about covering it from prying eyes and fingers)

[M_a_t_t]

The best handling conditions are when all 4 wheels have the same weight on them. I couldn't find the article I was reading on doing it diy, but its called corner balancing. I would imagine with motor, transmission, and (half?) the batteries in front it would be pretty front biased.

I would go for one of two things probably:
1. remove gas tank and put the batteries in its place, chargers in spare area

2. CUt a whole in the floor and put a box similar to this to gain access to them from inside, then put it all in there. If the gas tank and spare area are next to/ above and below each other.

However, I don't know exactly what the layout of your car is, but that is what I would go for.

Good luck

[Stubby79]

I spent yesterday cleaning up the stuff inside the cabin.

Field controller is now installed behind the glove box, where the old ECU was:


And I've re-worked it so that the controller is always putting out a minimum of 14-volts/amps, as I noticed the field voltage was sagging running off the accessory battery, and with 144v going to the controller, the motor would arc if you nailed the accelerator. No more troubles now that the minimum field voltage turned up a bit.

While I was at it, I fixed the no-power situation at the cigarette lighter (it wasn't plugged in at the back), and installed a mini-relay to control turning on and off of the field controller. No more manually turning it on...

I have also reclaimed the passenger foot well from the 3 batteries I had sitting there, and there's no wiring dangling down. Batteries were relocated to the trunk (for now), accompanying their other 3 brethren. There they were wired in 3S2P (36v, 60ah, vs, say, 72v, 30ah), and had a breaker installed, just in case:



Temporarily to keep prying eyes and fingers out:



"Finishing" things off takes an awful lot of time and effort. That took me all afternoon and then some.

Today, I went down and ordered some plastic to be cut for battery covers. When I got back, I decided to try and "fix" one little annoyance...the noise coming out of the vacuum pump:



That's a small-engine muffler. My EV now has a muffler! (??)

Wrapped it in duct tape and stuffed it back in it's hole:



When I formally insured it the other day, I had them change the fuel type to match, so no cop can give me a hard time about it:



And an as-she-sits photo, reminding me to look in to the rust at some point:

[MetroMPG]

Fun update!

Love the muffler (how much of a difference did it make)? We never bothered with vac assist on our brakes, but if I were doing it again, I think I'd add it.

I have also reclaimed the passenger foot well from the 3 batteries I had sitting there

Been there, done that! First test drive I made was with a whole lotta lead sitting on the passenger floor.

[Stubby79]

Originally Posted by MetroMPG

Fun update!
Love the muffler (how much of a difference did it make)? We never bothered with vac assist on our brakes, but if I were doing it again, I think I'd add it.

Huge difference. About on par with a running engine now, instead of a full size air compressor. Which is what it is, just small and used in reverse.

It was loud enough to be embarrassing (not that anyone looked over, but still), and made me not want to turn her on in the wee hours of the morning lest I disturb the neighbors. Now it's a mellow thrumm.

The muffler by itself only made a minor difference. Putting a second piece of hose coming out of it made it really quiet. (Something to remember if using one of these as an engine muffler?)