I'm hoping someone might help troubleshoot my Rad battery issue - I've gone pretty far down the rabbit hole and I *suspect I have a bad Battery Management System (BMS) :-\
If anyone has any knowledge to confirm (or discount) this theory - or even point me to further troubleshooting steps - I would be most grateful! I found this video on replacing the BMS - so if one of you battery gurus agree that the BMS is the problem and that there are no secret tricks to *reset the BMS, I'd love any feedback you have on the video: https://www.youtube.com/watch?v=wJyFALSY9Dk&t=934s.
Below I've described the issue and my troubleshooting steps (with pics). Thanks In Advance!
- The issue occurred while I was pulling my 70lb dog in her trailer. We were cruising some decent hills - I'm sure everything was hot - and then we hit a big construction pothole. The power gave out. The battery has not worked since. (attachment 1)
- I have two ~2019 Rad Citys. This made troubleshooting easier as I have two batteries to compare. By switching batteries between bikes I was quickly able to isolate it was a battery problem.
- On the good battery fully charged with the key in the on position, I get 53 volts. This is slightly over 48, as expected when fully charged. (attachment 2)
- On the bad battery charge status kinda unknown with the key in the on position, I get ~21v. Pretty sure that's why it won't power the motor. (attachment 3)
- On the bad battery, if I plug it in to the charger, I see the proper voltage ~54v. In the last bullet I will show you that the charger doesn't turn red on the bad battery (to indicate charging) as it does on the good battery. (attachment 4)
- On both batteries I have the lock in the correct position. On the bad battery I checked continuity - the lock behaved correctly in that when unlocked there was no continuity, but when in the position showed in the picture the continuity was good. I think that rules out the lock (attachment 5)
- On the bad battery I replaced and validated the fuses. When I looked at the fuses I could tell that the plastic mold was broken. When I opened the battery case I used some plastiweld to 'fix' the mold. I replaced the fuse and validated continuity at the wire. I think that rules out fuses - despite the wonky repair job. (attachment 6)
- On the bad battery I validated that the voltage at the wires leaving the battery and going to the bicycle connector. It matched the connector - ~21v. The connector looks pristine. I think this rules out the connector (attachment 7)
- As mentioned above, when the rad charger is plugged into the good battery, the charger reads 'double red' for charging. When the rad charger is plugged into the bad battery it remains green and red ---as if it is not plugged in or not communicating with the BMS. I think this is an indicator that the issue is the BMS. (attachment 8 Bad Battery charger indicator lights, attachment 9 Good Battery charger indicator lights
Really looking for any thoughts at all on this one. I'm definitely out of my wheelhouse, but I'm a techie. Soldering and battery spot welding are not out of my realm of capabilities - in fact, seems like understanding how to make/repair battery packs will be an increasingly useful skill so I welcome the learning.
TIA!
looks like you have done a good job troubleshooting. I am with you in thinking it is the BMS.
there are used batteries on facebook market place and ebay occasionally.
You can send the battery in for repair. There are a few places on the west coast that do that sort of thing.
I think there are some tutorials on youtube on replacing but not sure where you would find the parts.
@inoxa - thanks for the confirmation. Looks like I may want to add 'how to make and repair battery packs' to my bag of tricks.