Hi David, The pictures that Jay posted show the brushes very well. They are installed in pairs, in 4 locations. In 2 locations, the brush nearest the end of the motor had braids that were worn, or corroded, or somehow damaged. On the brush where the braid was completely gone, it actually looked like some corrosion (slightly green). On the other brush, the braid was broken somehow (frayed). It didn't look melted.
I agree that I probably have a controller problem. I also understand that Kelly controllers are not the highest quality, so I'm not too surprised. I think the controller is putting out a maximum of 60-70A or so, which is barely adequate at full battery voltage, but really pitiful when at low voltage. I hope to confirm that before spending money to replace the controller. Thanks for the ideas on dummy loads. I think that's exactly what I need. The motor rotation and brush timing is correct for the Honda. When I bought the car, it wasn't and the brushes and brush holders were damaged. The first thing I did was get all that fixed. Thanks for the suggestions! Mike > On October 31, 2017 at 3:01 AM EVDL Administrator via EV <ev@lists.evdl.org> > wrote: > > > FIrst things first: find out what's going on. You need a proper ammeter so > you can measure the actual motor current. If you have one measuring battery > current, why not move the shunt so it's measuring motor current? > > Alternatively, you could buy another ammeter. The ones sold by EV parts > dealers for in-car instrumentation are usually a shunt (typically 500 amps > at 50mv) and a millivoltmeter. I see a cheap one on Ebay right now at less > than $23 shipped. I wouldn't want to vouch for its durability or accuracy. > > You can get the shunt only, substitute a DMM for the meter, and do the math > yourself. I recommend having a passenger read the meter for you. > > My fist inclination is to say that it sounds like you have a controller > problem. I've seen logic failures in 1980s vintage PMC controllers that > caused them to act like the battery was flat and limit drive current to 50 > amps. I don't know whether a Kelly would fail in a similar way, though. > > In any case, FWIW, Kellys aren't exactly considered the upper crust of > controllers. :-( > > What you need to test the controller safely (in addition to the ammeter) is > a dummy load of some kind. Some EV hobbyists build them, usually for > battery testing, with electric water heater elements in a barrel of water. > That could be a lot of elements, though, since a 4000 watt 240v element will > only draw 1250 Watts (~8.7a) at 144v. > > Years ago I used a fan and heating strips from a derelict heat pump to make > a dummy load. The nice thing about using open nichrome wire elements > instead of the sealed elements from water heaters was that I was able to > center-tap the coils and parallel the halves to make the elements use more > current at lower voltage. It was good for around 100a at 144v. > > Maybe others here will have more dummy load suggestions. > > As for the motor, I don't think that unseated brushes would inhibit motor > current that drastically. I could be wrong. > > Try running the motor on 12v (no more) with the trans in neutral, or drive > wheel end of frame on jack stands. Does it run reasonably well with minimal > brush arcing? > > Your brush problem report is puzzling. > > I don't understand "the left side on both brushes was mostly shot." I've > never thought of brushes having a left or right side. > > If by "shot" you mean brush wear, that much is not normal. IIRC, GE once > estimated that their DC motor brushes were good for at least 250,000 miles > of EV use. > > According to the evalbum entry, you have a Honda with reverse motor > rotation. Are you sure the brush timing is set correctly for that? Maybe > your brushes were eroded by excessive arcing. > > When you say "On one brush, the copper braids were completely gone. On the > second brush, the copper braids were nearly gone," do you mean that the > brush pigtails were burnt? That seems like a different issue to me. > > I'd lay pigtail burnout to gross overload at low speeds or stall. I did > that to the brushes in my Comuta-car motor when starting on hills. But you > just don't see that kind of overload with a controller limiting the current, > and ADC 9" motors are a lot more durable than my C-car's feeble little 6hp > GE. So this seems odd too. But maybe I'm misinterpreting what you wrote. > > David Roden - Akron, Ohio, USA > EVDL Administrator > > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = > EVDL Information: http://www.evdl.org/help/ > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = > Note: mail sent to "evpost" and "etpost" addresses will not > reach me. To send a private message, please obtain my > email address from the webpage http://www.evdl.org/help/ . > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = > > > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA) > _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
