I hope everyone is doing ok these days.
The lithium ion conversion now has 13 months on it and 282 miles and I am still pleased with it. The cart is driven 5 or 6 days a week and is charged every week or 2.
There is no BMS on this system and at he beginning I was wondering if there would be any problem with the Li cells staying balanced, that is, all keeping approximately the same voltage thru all the charging cycles The system has 7 modules, for a total of 14 cells, with a nominal voltage of about 4 volts per cell. I carefully watch the system voltage on the "Cycle Analyst" to try and spot if anything odd is happening. I recently checked the voltage on all 14 of the cells after they were charged. The voltage varied from 3.989 volts to 4.005 volts for a spread of only 0.016 volts (16 millivolts). That is totally in the acceptable range and I didn't need the expense and complexity of a BMS.
During the 13 months, I have made 3 fixes/changes. One was replacing the cheap battery charger with a cheaper ($43) one. The second one is still holding up fine but ocasssionally the fan squeaks on startup. If I unplug the charger a few times the squeak stops. The second thing was replacing the 0-5k rotary throttle pot with a linear pot. I wasn't happy with the original pot linkage and the linear pot was a lot easier to get a nice smooth resistance output from. The third fix as a loose screw on a wire in the reverse control circuit. It manifested itself as a herky-jerky motion in reverse. Tightening the screw made it all better.
But I do have a curious problem that I need to get some expert advice on.
Before I did the Li conversion I changed out the motor to a High Torque model 42A from D & D motors. It has worked fine, I guess. but not having any golf cart experience I really don't know for sure. Here are symptoms. There is a 300 yard long steep hill on my property. When climbing this hill at full throttle, most of the time everything is fine. But sometimes, part way up the hill I get what feels like a bad carburetor bog. We all remember those, right? When it bogs, the amps drop from about 110 down to 40 or so. If I let off on the throttle and try again, it usually takes off again at 110 amps. I think it happens more during hot weather, but am not sure. I have stopped when this happened and felt the controller and cables, etc, and nothing was even warm!
Now here is the kicker. The controller is only an SPM225. I have it programmed to a fairly mild speed and torque curve, but I know something is wrong. The controller was new and I don't think it had this problem originally. Even though I have the controller programmed to 200 amps max, the amps never go above 150 on the voltagedisplay. I know the battery pack can deliver a lot more than 150A. I am wondering if the controller is just too small? I bought it because it was new, and really cheap, wondering if it was big enough for the task
Other than the full throttle bog, and not drawing as many amps as I think it could/should, it works fine. Does anybody have a suggestion on what I could check or do?
Thanks in advance, Lloyd