Electric car conversion: Project ForkenSwift

[MetroMPG]

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

[MetroMPG]

Video feedback:

DAX:

Great video Darin!

zpiloto:

Man that is so cool!! What kind of shape are the batteries in after the test drives? Nice rolling stop by the way

I was thinking that since you have a ready supply of used batteries, you could continue to collect them, charge them, load test them, and then keep the ones that do the very best. You will probably find a lot of really bad ones, but all you need is 8-10 really good ones, right?

Nice video. It really is amazingly quiet. You might need some sort of very soft horn or beeper to use in parking lots and near pedestrians so people don't step out in front of you. Something that plays the sound of George Jetson's spacecar would be perfect. :-)

Also, is there an concern about hydrogen buildup in the charging area? I don't know much about batteries.

SW's puntastic response...

That's terrific! Thanks for showing us the current state of the tests you're conducting. I was shocked to see that the Neon guys got a charge out of it too.

[MetroMPG]

Man that is so cool!! What kind of shape are the batteries in after the test drives? Nice rolling stop by the way

They're not good. Amazing what you can learn with a DMM: the pack is very unbalanced (batts resting at very different states of charge after use & charging), and I've already found several that suffer from serious voltage "sag" relative to the others, when measured immediately after loading them up (driving). And I've also found a few batteries that appear reasonably healthy.

That didn't even qualify as a "rolling stop"

I was thinking that since you have a ready supply of used batteries, you could continue to collect them, charge them, load test them, and then keep the ones that do the very best.

That's probably what we'll do, for now. I'm going to ask the forklift company guy who's been supplying me with batts if he'll connect me with his supplier. There's apparently a guy who drives around delivering new & picking up used batts. I want to meet this guy

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Also, is there an concern about hydrogen buildup in the charging area? I don't know much about batteries.

Yes. The closer a flooded battery approaches full charge, the more it will "gas", releasing H2 and O2. Many conversions with batteries enclosed in the trunk or in battery boxes in the passenger compartment (ie hatchbacks), run brushless fans to circulate outside air through the boxes.

Quote:
Originally Posted by SW
That's terrific! Thanks for showing us the current state of the tests you're conducting. I was shocked to see that the Neon guys got a charge out of it too.

You're welcome. I was quite amped about the whole thing myself!

[MetroMPG]

Also did a speed test: achieved 42 km/h / 26.1 mph on a flat road, which while it doesn't sound impressive, is 1.1 mph higher than the speed limit of NEV/LSV's.

I outpaced a 12 year old on a bicycle to around 30 km/h. Barely.

The road dipped slightly after reaching that speed and then leveled out again. I got up to 49 km/h (29 mph) in the descent and the car seemed to hold that speed up to where I had to brake for a turn.

And by the time I reached that turn, one of the undersized cables on the pack was warm enough that I could smell it.

All of which is to say, with a better pack and proper wiring, I have no doubt the car will be adequate for in-town driving.

[MetroMPG]

Someone points out that driving and EV efficiently must be very different from an ICE...

You're right - it is a totally different ball game, and there's no EV driver's website where I can go talk about the best techniques for driving the thing.

It was in 2nd gear for the speed run. I've read that electric motors are more efficient in the neighbourhood of 3k RPM, and that's roughly where it would have been at that speed. But... low RPM gives more torque, so maybe I should have shifted. Dunno. Don't have enough juice yet to do repeated runs

I may have even read somewhere that you UPshift an electric car for hill climbing (if your controller and pack can deliver the extra juice required to make the torque).

For regen, the electronic motor controller has to be designed to do it. The two that we have don't have that option. Still, it's better to coast where possible, rather than regen (unless you HAVE to brake). The 5 k neighbourhood run I did on the weekend was with lots of coasting to stops with the gear selector popped into neutral - almost no brake use.

[MetroMPG]

On the issue of the car being too quiet around pedestrians, someone suggests putting hockey cards in the spokes

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You're closest to what I'd actually like to do: I want to use a bicycle bell. Maybe hooked to a solenoid to sound it.

I'm actually already fairly concientious towards pedestrians since 40-50% of the time the Blackfly is moving, its engine is off. I often tap the horn to let people know I'm there.

[MetroMPG]

RH77 jumps in...

I just had a chance to watch the vid (sorry a bit late -- couldn't do it at work )

I love unsolicited reaction by the guys on the street when it's explained as electric.

Bystander: "Bull****. Really? Awesome!"

Meanwhile back at the repair car, $20 is exchanged for an "I told you so" between buddies.

BTW, do you cut your own vids? Good background music.

So regarding the battery pack inequalities, what can be done (cheaply and easily) to prevent this problem?

Do you need all batts to run? ...or can you run on x-number until discharged, switch to the next set, etc (or would that discharge them too quickly?) Or you could alternate among them -- guess this would let some "rest" while others were in use, but put a lot more strain on the cables. ...would probably require a series of heavy-duty solenoids or relays.

Do you (or have plans to install) a Voltage readout inside?

OK, I'm done with my 20-questions

Keep up the great stuff.

[MetroMPG]

OK, so what Metro parts are leftover to sell?

Not enough to pay for replacing the batteries we're sure to murder as we figure all of this out!

(But because you asked: mainly, just a relatively new gas tank.)

Originally Posted by RH77

Bystander: "Bull****. Really? Awesome!"

Yeah - that was classic. Couldn't have scripted it any better if i'd tried.

And yes, I edited. It was 95% "real" footage of the maiden voyage, but I went back the next day to get 2 specific shots that didn't turn out (notice the part where the car first rolls out of the garage, shown from the side? My shirt is a different colour in that bit than in the rest! There are a couple of other "continuity" errors that aren't hard to miss if you like looking for that stuff.)

Quote:
So regarding the battery pack inequalities, what can be done (cheaply and easily) to prevent this problem?

1) Frequent "equalizing" charges - which is hard on the "good" batteries;

2) individually charge the duds - which is a pain in the butt;

3) add battery regulators (electronics) that shunts charge to the weaker ones - which is $, or you have to be somewhat skilled in electronics, which I ain't;

4) keep taking in used batts and evicting the worst ones from the pack;

5) buy a new matched set of batts.

I'm leaning towards #4, since we're in no panic to have the car in regular service yet.

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Do you need all batts to run? ...or can you run on x-number until discharged, switch to the next set, etc (or would that discharge them too quickly?)

If you're carrying say 8 batts in the vehicle, you'll get more range if you discharge them all at once than if you discharge them 4 at a time. "Peukert's effect."

Quote:
Do you (or have plans to install) a Voltage readout inside?

Definitely. Drawing a battery down below a certain cell voltage under load will permanently damage it. The only way to know for sure is to be watching. (I haven't been. Batteries have already been (further) damaged than they were when we got 'em.

(EDIT: or you could have some smart electronics watching for you, and take over with a current limit over-ride to protect the pack if you discharge them too deeply.)

Learning more every day.

[MetroMPG]

Today: finally some action on the welder front. Went with my brother to see a guy he knows who's a welder by trade. Neat guy - does artsy stuff on the side with his machines at home - sculptures, etc.

Keep in mind my brother has done a little welding before - stick & MIG. But I've only ever tried brazing..

Anyway, we both described the kinds of things we had in mind for using a welder, and he advised us to get a middle of the road wire-feed machine. There are a couple on sale around here for about $300. MIG capable, if we want to add that on, but he said flux-core wire will suffice.

He has one of each in his shop, and he gave us a super quick demonstration, then asked if I wanted to try. So I got to weld my first bead today (wire feed). Kind of cool Said I was OK for a beginner, too.

For joining 1/8 angle iron for the batt trays, he said the machine probably won't quite do a big enough bead first pass, but you can always go back over it a second time and build it up.

So now we just have to actually pick one out and buy it.

[MetroMPG]

Guess what I bought today



It's fun when projects justify tool purchases.