Battery connector melted in Bafang

[draharz]

Hello,
I was playing around with user profiles for the excellent Daniel Dissons firmware for my BBS02 (User profiles (BBS02B, BBSHD) for BBS-FW (Daniel Nilsson's Open Source Firmware)). For around a year I had no issues but then one day (possibly weeks after I've changed something that I can't remember) one of my battery charging pins has pretty much started to melt. The ebike suddenly could go only around 10km/h as if it had no power and then it stopped working. You can see what happened to it in the photo attached.

I have replaced the connector with a new one and flashed one of the default profiles so I assume it should be working good now. As I want to avoid this issue happening again I would like to ask if anyone more knowledgeable could say what kind of settings can cause this to happen?

 

[fechter]

The max current is the only setting that would really matter, but the connector failure was not likely related to the settings.
More likely the mating female contact lost tension due to bending or became corroded and developed a high resistance. Bad connector design. I hope you also replaced the mating connector or cleaned and tightened the contacts somehow.

 

[Hwy89]

I doubt that any of the settings you changed caused the problem. Poor electrical contact for whatever reason leads to increased resistance and heat buildup at the connector. If you replaced it with a new one and have a solid connection your problem is solved until the new one wears out.
Each time the battery is plugged in there is an arc as the capacitors in the controller recharge. This will happen even if the controller is turned off. Each arc leaves a bit of carbon burn on the contact and gradually increases the resistance. You could look into anti spark circuits or connectors or just keep an extra connector on hand and replace when needed.

 

[draharz]

Interesting! Thank you for the answers. It seems then that those chinese bafang batteries have some kind of lifespan in the end. It lasted for almost 2,5 years so I don't mind replacing some parts (I would even expect to do some repairs at this point). I did my best with the replacement and did a test drive and everything is working fine.

 

[Mnaq]

I had exactly this happening to me after 2,5 years of daily commute. Same connector. I noticed some ozone smell before it happened and erratic behaviour a few times. Mine was really melted both on the battery and dock (after applying contact spray to get me home). But I managed to replace the connector on the battery for the extra male XT-one on the that came with the motor-kit so now I can use the battery as a backup but strapped onto the cargo holder.