Electric car conversion: Project ForkenSwift

[MetroMPG]

Video reactions...

omgz pimpness MetroMPG!

Props to you man. Now I need to get off my *** and get mine going!

Originally Posted by DAX

Haha, great video!

[MetroMPG]

Miscellany:

- Calculated the motor RPM in the video: 1387. Compare to about 2200 on the bench when not spinning the drivetrain (which has no oil in it).

- Details on the brush timing adjustment:



Above, you see a few things:

- The new set of bolt holes on the end cap (very top) which anchor the brush plate. The new holes are oblong, so some fine tuning is possible.

- The total brush adjustment was a combination of rotating both the brush plate PLUS the end cap, and you can see the old end cap bolt hole on the bottom side of the brush window.

- Lastly, I made a couple of new mini bus bars to attach the heavy field wire to the brush plate. Old bus bar sitting on top; new one shown connected in the brush window.



Above: one of the end cap bolts in its original location was snug against the left side of this brush window openings. I needed to make a little cut-out to accomodate the new hole. Easy as pie: the end cap is aluminum - so easy to cut & drill.



Don't think I posted this yet: motor in the car.

[MetroMPG]

On the motor red line question - got another reply from the Guru:

Quote:
The fact that this is an older motor with (from what I could see) an almost uncut comm is a plus actually. That Otis motor has a tad smaller comm dia. than an ADC8 and should be safe to 6000 rpms (at least in short durations.)

That means we're theoretically good to 28 mph in 1st gear, 52 mph in second, or 77 mph in 3rd (not that the car's going to see much over 40 mph @ 48v, if that).

Practically speaking, we could just leave the car in 2nd and forget about it.

Silveredwings - how did you make that gear/speed graph for your BMW in the transmission thread? I tried figuring it out, but I couldn't get Excel to cough out the right chart format.

Edit: next on the to-do list is raid the scrap yard for a bunch of car battery cables/connectors to string together a 48v test pack. And then hook up my golf cart controller.

[MetroMPG]

Found a fresh entry in the EV album - a 48 volt Metro (using 8 6v floodies).

He claims a top speed of 53 MPH (85 KPH) and a range of 22 Miles (35 Kilometers)

http://www.austinev.org/evalbum/994

[MetroMPG]

Ben gets cheeky:

Originally Posted by SVOboy

Whatever happened to september, that's all I want to know.

September flew by in a blur of laziness and lack of motivation, I guess.

Hurdle du jour: I went to the junkyard and got enough battery cables/clamps to make a securely connected 48v pack (instead of a tangle of jumper cables like last time), which we strung together this evening from a combination of boat batteries and old starting batteries.

We hooked up my eBay Curtis golf cart controller. There was a big spark making one of the connections, which we weren't expecting. And then! We couldn't make it work.

So we quit this evening not knowing if it's the controller or the pot that's not working, or if we somehow fried the controller. I believe controllers "charge" before they go into action, so that may be the source of the spark.

I've got a question out on the Citi/Comuta Car list, since they often upgrade to controllers from their contactor setup.

[MetroMPG]

Quoting myself from earlier...

Quote:
Originally Posted by MetroMPG
I believe controllers "charge" before they go into action, so that may be the source of the spark.

I did some digging in the EVDL archive and I was correct in my belief about the initial spark:

Quote:
When you first get in the car, the controller caps are discharged and appear as essentially a dead short. If you simply close the main contactor and apply full pack voltage to the controller, the inrush current can be *huge* (as in 100s of amps).
(from http://autos.groups.yahoo.com/group/.../message/78835)

That would explain where our spark came from and why we only it once: we charged the caps in the controller when touching the pack cable to the controller. It also serves as an explanation of the function of a precharge resistor (to protect the caps & the contactor - or cable tip & controller terminal, in our case - from excessive current inrush).

So tomorrow, I should look at the pot and see if it's the problem.

[MetroMPG]

Tried and failed again to get my eBay golf cart controller to work today. (It's not the pot.) Email from an electronics tech on the EV list says it's probably no good (after doing a couple of DVM tests he suggested). Drat. Maybe it's a good thing I haven't left feedback yet - If I'm lucky I can get the seller to make good.

So I started reading up on the GE EV-1 controller that came with the forklift. It's more complex than the Curtis to install, and it has to be configured differently for its new life. I've got lots of info though: 3 maintenance booklets with operating descriptions, pin & wiring diagrams, schematics, the works.

I was just being lazy and putting off the hard work. I would have liked to get the car going on the Curtis, and then swap over to the EV-1 later.

EDIT: on the plus side, Ivan's brother donated a 36v bulk battery charger with a timer to the project. He got it from his work (they were switching to smart chargers for their forklifts).

[MetroMPG]

Man, my tinker time this weekend was fruitless and frustrating.

Couldn't get EITHER controller to work (had another suggestion on the Curtis that I hadn't tried last week so I was back at it today).

Also, I learned in my reasearch that the GE EV-1 controller that came with the forklift isn't really well suited to small battery packs such as in a converted car (even "regular" size packs, not the 6 or 8 batts I'll be using).

The EV-1 has no capacitors on the input side, and it switches at a fairly low rate (around 300 hz), which means that you get the equivalent of "water hammer" in the current coming from a small battery pack.

The result: the EV-1 controller will both shorten battery lifespan and lower range per charge compared to a modern controller. You can retrofit a string of capacitors to improve it, apparently, so that may be something to look at.

None of that matters if I can't get the durn thing to work in the first place. I'm relying on the wisdom of the EVDL to help. I'm sure it'll get sorted out eventually.

[MetroMPG]

Here's an interesting thing: that

Youtube video I made of the motor spin-up

has been watched over 500 times.

[MetroMPG]

Think I just discovered why the Curtis doesn't work. In its original application (Club Car golf cart), it used a complicated proprietary potentiometer, not a standard 0-5k pot. Found this out by joining a golf cart forum - someone pointed me to a wiring diagram. So maybe one of them will buy it from me.

I also discovered I'm not the only person who's faced this exact problem with this specific Curtis model. In various forum archives I have found 2 other ev converters banging their heads against the very same wall.