Hello everyone, I'm hoping for some advice on a motor performance problem that has been building for a while.
I have an ADC FB1-4001A 9" Series DC motor with a Kelly KDH14100D controller. The batteries are 13 kWh of ThunderSky LiFePO4 100 Ah cells. That is 45 cells that are nominally 3.2V for a 144V system. The controller is theoretically capable of 1000 A, but I've always taken that with a big grain of salt. The vehicle is a Honda del Sol weighing about 2550 pounds. Details at: www.evalbum.com/2778 Over the past 6 months, my acceleration from a standing stop has been getting worse. In conjunction, the current draw at low RPMs has also been getting worse. (I only have battery side meters; no motor side meters). I found a really good discussion in the EVDL archives from 2009 that was very applicable. In that discussion, the original poster was asking about a problem similar to mine. He had measured several controllers (including lower-performance versions of the Kelly similar to mine) and posted RPM vs. battery current values. In his example, the various controllers were drawing between 150-200A from the battery system at 120V and 2000 RPM. During the discussion, it was pointed out that battery amps would be lower than motor amps at low RPMs, until the motor was running at full pack voltage. The calculations showed that each controller was running at its current specification for constant load to the motor. In my case, with supposedly a higher-power controller, I'm only drawing 60A at 1000 RPM and only 100A at 2000 RPM. At about 3000 RPM, I hit 150A and start to cap out at about the maximum my batteries will put out in cooler weather. I'm not worried about the 150A, but 60A at 144V (about 8kW) is very anemic for pulling onto the highway! With that background, my question: I know this could be because my controller is no longer putting out rated power for some reason. Is it possible there is some other reason, such as brushes? The motor and brushes have almost 25K miles on them. I haven't checked them for the past few months, but hope to tomorrow. Other than all making contact and not being worn down too much, is there anything else I should be looking for? Does anyone have other ideas about what could cause my power draw at low RPMs to be changing over time? Thanks for any ideas! Mike _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
