Electric car conversion: Project ForkenSwift

[MetroMPG]

You're invited.

I still think the biggest bang for your buck would be a 36v/72v parallel/series setup with a 36v controller for your low speed/smooth operation and 72v direct connection for 100% efficient (in the controller sense) strong accel, higher speeds & cruising.

PS: http://galaxy22.dyndns.org/ev-talon/

72v Eagle Talon - 54 mph on level ground.

[MetroMPG]

So, shipping was a killer (as usual) for the 400A controller to Canada. Total in Canadian pesos for the transaction: 141.69

So the $20 controller upgrade has gone up a bit. Still, 57 bucks is not bad for an almost 80% increase in peak current! I can hardly wait.

[AndrewJ]

80% wow, you're gonna be burnin' rubber in that thing!

[MetroMPG]

300A controller came today. After supper project!

I realize I'll just have to pull it out to replace it again with the 400A unit within another week or so, but I can't resist. Plus it's not that big a job to replace.

[MetroMPG]

So here's what "20 bucks" and 20 minutes of tinkering gets:

0-50 km/h in 25 seconds vs. 36 seconds on the old controller - fresh off the charger in both cases, same road, colder temps today though (so possibly slower).

0-50 km/h in about 35 seconds after 10 km of driving.

New top speed seen: 72 km/h (45 mph) vs. 66 km/h (41 mph), on the same stretch of road (slightly downhill).

This controller makes the car noticeably more driveable in traffic. The power's there when needed to accelerate more briskly.

It may be premature, but I almost want to say that 300A is enough. Still, I can't wait for the 400A unit. Hey, I don't have to use it, but it's nice to know it's there if needed.

[bennelson]

45 MPH!!!! Cool! At 48 Volts and 300 amps?

I think I will be plenty happy with a 72 volt system with a 300 amp controller

[MetroMPG]

Yup. Keep in mind you probably won't actually see the controller's max current output very often. I saw the ammeter bounce off 300A maybe 4 times in 10 km - of trying to max it out. Typically you see high amps when you upshift, but as the motor speed increases after each upshift, the current draw falls off pretty quickly.

I think the ForkenSwift could easily do 50+ mph on the flat .. if I had enough flat road to try it.

I think you'll be happy with 72v/300A.

[TomEV]

Have you tried field weakening to see if there is a top speed increase? Relatively easy to try.

[MetroMPG]

Haven't tried it, no. Unfortunately, it's not as easy to do with this motor as some others. We don't have the external (through the case) field terminals. Ours are soldered internally in series with the armature.

On top of that, I'm less interested in top speed as acceleration. The highest speed limit of any road the car uses is 50 km/h (30 mph).

Have you tried it?

[TomEV]

Yep - works well in the Citicar. I linked a video of the experiment in this forum in the Field Weakening Experiment thread.