Ben Nelson's Electro-Metro Build thread

[bennelson]

I found a photo of the four-in-a-row radiator batteries.



It's not the one I was looking for with the exact same batteries as I am using, but I think you get the point.

PS: That guy has a great web page, with lots of photos, of his '97 Swift EV conversion

Homepage - EnviroKarma.org

[bennelson]

Here's what I have been up to lately.

http://www.youtube.com/watch?v=ayDbefcj9SY

Also, since I was tearing everything out, I took out the passenger seat.
I am starting to appreciate how easy everything is to work on in a Metro. I just pulled out 5 bolts, all with the same head size (12mm, same as EVERYTHING on this car) and the seat pops right out!



With all that additional space, there isn't a whole lot stopping me from just setting more batteries right in there!

I also tried the TURBO again. On the one straight and flat stretch on the way to the bank, I hit the turbo - this time in 3rd gear to limit current.

The ammeter shot up to the 300 amp limit, but after a few seconds, started coming back down into the range of the ammeter.

The car briskly accelerated to 45 mph, and then I had to let off of it because of the speed limit there.

So, using a lower gear to limit amperage with the turbo does seem to work, but it's still pulling more amps than my batteries are really happy with. Once I get another six batteries in parallel, the amperage per battery will be half, and it shouldn't be as bad.

I also sketched out on paper what I would need for cables to add six more batteries in parallel.

I believe that I would need 7 new short cables. To spring 6 batteries in series, you need 5 cables to connect them. And I would need two more cables to make the parallel connection to the other half of the pack, one cable on the negative end, and one on the positive end.

Seven cables with two ends each means I need to get my hands on 14 terminals and a crimper. I still have plenty of heavy welding cable to use to make cables, just no terminals.

To make it into a 144V pack, I think I only need to reverse half the existing cables, but I don't think I need to get any new ones!

[MetroMPG]

I thought we were going to see a vid of the turbo in action! Oh well.

And I love the batteries on the passenger floor board - I haven't seen that since we did our first test drive. Batteries in all 3 passenger floor areas.

[MetroMPG]

PS - you're going to have to start aeromodding the car since you're turning it into a high speed monster. You realize that even at just 30 mph, about half the power required to push these cars down the road is used to overcome aero drag.

[bennelson]

Well Darin, I DO love the look of your black Firefly!

Those rear wheel skirts have always been very classy.

I have also been intrigued by pizza-pan wheel covers since the first time I saw them.

It would be hard for me to video tape the turbo in action. Right now, I have to hold a momentary-on switch in my right hand, and hold the switch in the up position to engage the turbo. I then have to turn the key off to disengage the the main contactor, wait a few seconds, and then let off the turbo switch.

I guess I could videotape the speedometer, but that's not really that interesting.

I need to talk to somebody about "flyback diodes" to figure out what I need to do to NOT fry my controller while messing around with all this.

The turbo sure is frighteningly fun though!

If only I had some way to "soft-engage" it!

[bennelson]

In my continuing quest for range, I have now maxed-out my batteries and GVW!

I already removed the back seat and have been comtemplating the best way to cut a hole in the floor where the backseat and gas tank below it were.

I figured I would check to see what would actually work first.

Since I knew pretty much where I wanted the batteries to go, I rigged up a temporary way to mount them to try it all out.

On the back seat, I used a couple of self-tapping sheet metal screws to zing in a piece of scrap angle iron to make a lip to rest a small chunk of plywood on. The front edge of the plywood sits on "the hump" in the middle of the old seat space. I made two little spacer wood blocks to support the front two corners.

I set four additional batteries on the plywood platform. I am starting to get smarter now. Instead of all batteries facing the same way, I finally figured to have each rotated 180 degrees from the last. That way, it leaves the middle of the battery open for a tie-down cross member.

To connect these four batteries in parallel to the four already in the way-back, I connected the positive from from string B to the positive in String B, and the negatives of both strings to each other as well.

It feels very strange to be connecting matching polarities like that, but nothing sparked or exploded!

I then still needed two more batteries to run in parallel with the two front batteries. I have to take the entire front end of the car apart to get to the radiator batteries. My master plan is to rotate them 90 degrees so I can fit two more up there.

Well, for now, I already had the two "turbo" batteries on the floor of the passenger seat. They already had cables running through the firewall to the reversing turbo contactors.

I disconnected the cables from the contactors and instead attached them, positive to positive, and negative to negative, to the front two batteries.

I think plugged in the Anderson disconnect. No sparks! No car leaping forward!

Looks good so far!

I turned the car on, and it started as normal. Click. (Key) Ka-lunk! (main contactor) Whirrrr! (Power brakes vacuum pump)

I went for a short spin around the neighborhood. The suspension didn't seem too bad, considering how weighted down it was.

My ammeter shunt is connected between batteries 5 and 6 of the original string (in the front of the car - radiator batteries.)

Since the other string of batteries is providing half the power to the controller/motor, the shunt should now read how much power is coming through battery string A, only half the total amount.

Sure enough, the ammeter reading seemed to be about half what it usually was. However, when I accelerated hard in higher gears, I was still able to get the ammeter to shoot up to 300 amps!

How is this possible? I only have a 400 amp controller! Either my shunt and ammeter are faulty (not calibrated to each other?) or for some reason, the motor is pulling more amps from string A than string B!

Any thoughts on this?

Also, I did notice that battery voltage sag was not as bad. I could gun the accelerator and the total pack voltage did not drop as much as it would have before with only the single string of batteries. I think this is an overall advantage as I now have the upper hand against Mr. Peukert and his effect on my lead-acid batteries.

I will try another test run tomorrow in the daylight and see what kind of range I can get.

In theory, it should be double what I had! (Hopefully, the gain against the Peukert effect will off-set the additional rolling resistance gained from the extra battery weight!)

The extra range should make the vehicle MUCH more useful! I am hoping it will be enough to make the vehicle practical as primary transportation while I convert my truck to bio-diesel.

[Edit]
Here are some photos of the parallel battery pack.

[bennelson]

Also, to give you a better idea of what range does, I have made you a handy map!




Basically, the inner most circle (purple) is how far I have been able to drive this winter. I can only go 5 miles because I can only get about 10 miles total, and I always need to drive back FROM wherever I drive out TO. This is just in-town. It does include: the pizza place, grocery store, library, and just barely, the bank.

The second ring (brown) is how far I could drive in the summer (or hopefully in the winter with the doubled-up parallel battery pack now). What's interesting about it is that there is nothing useful to me in this range, other than maybe making it to my parent's house and recharging a bit while there.

Ring three (redish) is how far I should be able to go (and get back from!) with my new parallel battery pack. That includes Hartland and Delafield, where I often work, and some bigger specialty stores that aren't available any closer.

Ring four (yellow) is pretty ambitious. This is my predicted range, one-way, on the new battery pack, in the summer. This assumes that I can drive someplace, park, and recharge all day while there.
I often work in Pewaukee and Brookfield. If I could recharge all day while there, that would mean that the only time I would need an ICE vehicle is for driving into Milwaukee!

I hope this gives you a better idea of how range affects the use of an electric car!

[bennelson]

I drove from home to my parents' house and back today.

Their house is just a little outside the range of the brown circle in the above map.

I ran some errands, then drove to their house and back. (I figured if I ran into any problems, I could always recharge there, or use tools, etc!)

Total trip was 16.3 miles. Much better than the 9.5 miles I was doing with the single string of batteries all winter!

The rear of the car rides really low. On harder bumps, I could hear a rubbing sound. I don't think it was the tire and suspension though. It was only on the rear-left corner that I heard it. That's where the charging port is, and I saw some wear on the charger port conduit. I think with the car riding lower, it swings out more, and barely catches the tire. I will have to zip-tie it over a little further.

-Ben

[Daox]

Woo, nice map. Looking forward to seeing you and your car tomorrow. You're bringing it, right?

[electricman]

Hey Ben, There are 50 pages on this thread - I only read through about the first, but wanted to say - way to go! Mine was converted by students - and I have only been working the later details so far. Electricfly - MyElectricfly.com

Using a motor like I have - it is a GE Series DC rated 20.9 HP at 90V x 184 Amps, and on the highwya I am able to do about 65 mph (105 kmh) drawing 185 amps but my 12V Group 24's sag back to about 75V from a starting 100V.

The thing is - what I have recently learned - is keep it to the 25 Amp rating on 12V Bat's to keep them alive, and that means - it is realy limited to about 20 kph (This is with the 12V Trojan SCS-150 Lead Acid Floodies). Of course - I have also had enought experience to run the batteries dead a few times - no I don't mean dead, sorry - I mean SUPER DEAD, which of course probably took and extra 50 + cycles off their limited life.

I have added to the analog Voltmeter and Ammeters it came with - a PakTrakr display with a Woodward After Market Components Enhance Display and learned even more about the issues with 1 or 2 of the batteries going south before the rest of them!

Check out my web site and blog.

Robert