Firefly Electric Conversion

[Stubby79]

I wound up ordering another "better" BMS, after looking up the specs for the one I had. While it is supposed to be for LiFePO4 cells and all, I did not like the voltage cutoff being 0.1v (per cell) higher than the better one.

So, seeing as it has the LEDs indicators on it, I feel more confident in placing the cells in place of the gas tank, and have ordered more/longer leads to allow the BMS to reside in the spare tire well, where I will probably also mount at least one of the chargers.

I was sold on the idea, until I looked at my photos of where I was planning on placing them under the hood. I'm on the fence again.

If I put them in place of the gas tank, I can't visually check the cells. This concerns me.

If I put them right up front, they're going to get smoked if I have even a small fender-bender. This concerns me. Probably more.

There's minimal difference to how the cells get laid out, so I can still continue with the wiring, even if I haven't completely made up my mind.

Progress? What's that?

I put the first pack back in and re-connected the wiring, so she works again:



I have plenty of little(reasonable, individually) tasks to do, besides the big task regarding the other battery pack. Vacuum pump and reservoir to go in. Rear wheel bearing to replace (since I "borrowed" the good hub/drum to get my other firefly back on the road). Chargers to go in, eventually. Synchromesh for the transmission. Not a lot, really.

I'll start plugging away on these.

To help motivate me, I got a good deal on Monday. I had offered the guy 1/3rd less(my normal money-saving tactic) than his asking price a month back, and left it at that. Assumed that was the end of it when I didn't hear back from him for a while. Got an email Sunday night, and I just happened to be traveling up-island Monday, so I picked them up on the way:



They're 14's, vs the stock steel 13s.

I like 5-spoke "star" wheels. They come across as "sporty" to me. Any more or less...doesn't.

They also happened to come with just the size tires I was hoping for (185/65), with about 50% left to the wear-bars, so I'm not out another couple hundred bucks finding tires and getting them mounted.

155s vs 185s:


Yes, the tread actually is 30mm wider. I expect they'll make the Firefly stick to the road a lot better around the corners.

They're 5lbs heavier each. And like the additional width causing additional rolling resistance, well...I'm willing to put up with the slight range loss for a nice set of wheels that makes the car more appealing to look at and drive.

And bonus! They're dual bolt pattern, 4x114.3 & 4x100, so they'll fit most small cars. And I like small cars, so they can follow me if I get tired of the Firefly. (They'll fit my Miata, and even have the OE sized tires on them)

Hopefully they will succeed in encouraging me to get on with things.

[Stubby79]

Wheel bearing is in. Now the wheel actually turns!

[Piotrsko]

the question regarding collision damage: when as the last time you totalled a vehicle?

So yes the batteries in the front and rear edges are potentially catastrophic, and the STO. of accidents isn't <1. good fusing, and electrically insulating the cells from shorting metals should suffice.

you do drive around in a fueled vehicle that has enough potential energy to destroy a small city if the fuel is correctly mixed with oxygen.

[RedDevil]

Originally Posted by Piotrsko

... you do drive around in a fueled vehicle that has enough potential energy to destroy a small city if the fuel is correctly mixed with oxygen.

Oh, the potential for disaster if the conditions are right for it...

Your car can give millions of people a sore butt if the metal is transformed into thumbtacks and placed on seats with the pin sticking upwards :P

[Stubby79]

Hi, remember me?

...No, me either.

Anyway.

A few weeks back I made this thing...



Today, I welded it in...



What terrible looking welding.

So now it looks like this...



And the battery will fit under the headlights...



That done, I felt like continuing with the next hurtle. So now I found a place and a way to mount this guy...



Another shot...



His buddy is just hanging around...but at least he's out of the way.



Look, a hoser!



Wiring up the second battery will be next, along with a transmission oil change...

[Stubby79]

Welp, I tried bench testing my mini controller with the current sensor I bought, and...it didn't work.

I couldn't get the hall-effect current sensor to change it's output, even with a decent current passing through it...

And the mini controller didn't like the input from the sensor, either.

I pissed away a couple of hours on it. Pulled out a traditional hall-effect throttle and it worked. Just not the sensor I bought specifically for the job.

I went back to my older plan...manual control.



That's my clutch pedal. Zap-strapped to it - upside down! - is the cheap hall-effect pedal I've had for ages to put in to an EV, but didn't need...

Zap-straps?! Yesm zap-straps. And upside down! So the sensor's pedal presses against the floor. It works really well, and no drilling or screwing around required!

Temporarily in the passenger footwell...



Three 12v batteries, and a cheap brushed e-bike controller.

Again, something I had intended for use elsewhere, once upon a time, but never applied to it. It works perfect for my needs...adjustable output (based on the "throttle" input on my clutch pedal), with a built-in 32-amp current limit. (of course, at 36v, the 1-ohm field coil would only take 36 amps anyway!)

No frying of relays or other such switches for me, and this puts the control fulling in my hands...well, foot, anyway.

I'll move the batteries in to the back at some point. Might even use smaller ones, since it will only sometimes be required to put out 30-odd amps.

Of course, I had to test it... 2nd gear was pretty pathetic for take-off and on hills before...now it takes off in 2nd at least as hard as my 3-cylinder does in 1st!

[Stubby79]

Took her for a couple of km drive to drum up some enthusiasm to get on with my wiring. Gotta say...it really feels like I'm driving a car with the engine stalled. My senses are totally thrown off.

2nd gear is just right for doing 50km/hr at 72v. The clutch field control will take some getting used to, but does great for getting up to speed; as soon as it stops accelerating, take your foot off the clutch, field weakens, and she will accelerate more. She will only do about 35km/hr at full field @ 72v.

Might need to quieten down the vacuum pump. In such a quiet vehicle, it's almost embarrassing. So is the feeling of a stalled engine and wondering if it's going to keep working after the next stop.

I'll get more confident in her when she's properly on the road.

[WyrTwister]

35 km/h in the top gear .

God bless
Wyr

[Stubby79]

Originally Posted by WyrTwister

35 km/h in the top gear .

God bless
Wyr

Wouldn't that be fun?

No, that's at "full field", with "only" 72v going in to the controller. The stronger the field, the more torque the motor puts out per amp, and the less RPM per volt. Since the controller limits motor amps to 500, this allows me to cram more amps in to the motor, producing more power.

I saw it sucking 300+ battery amps at one point (I was driving and couldn't watch it every second) in the middle of accelerating, so that's 25+ hp coming out of a "little" motor, and at a lower RPM than the original 3-cylidner would have been running to make that much power.

If/when I bump it up to 144v, squeezing more amps in to it will be easier, and I won't be limited to 35 km/hr at full field in second; I'll be able to take it all the way up to 50+. And third gear should let me take it up to 90+.

[Stubby79]

Been plugging away at the extra wiring for the second battery pack.

BMS:



Charging port:

http://ecomodder.com/forum/attachmen...1&d=1502155746

Test:



Adds up to the usual rigmarole of additional battery protection stuffs:

http://ecomodder.com/forum/attachmen...1&d=1502155774

This one is built a bit differently than the first...two strings of 12 cells, instead of one big brick of 24. I had to set up the wiring to allow them to come apart:



That will be it for a few days. They're ready to drop in to the car...then I need to change the set up of the heavy gauge wiring to accommodate it.