So I rode my board for about 100miles since the beginning of the build and I experienced last evening a strange thing, I plugged my board with my banana plug as usual to my Hobbyking 8S bms, (Without opening my enclosure), everything worked well, red led as usual, charging.
I left the board for like 10 minutes and the led turned to green like if it was fully charged.
Since I was at only 50% when I plugged it i was supprised because it’s usually not this quick, I turned on the board and I was at 32.5V, so about 80% battery and it won’t charge anymore.
I though about a weld spot which could go off because of the vibrations so I removed the enclosure and everything was surprisely ok.
Then I tested the charger directly at the output because my board electronics were looking good and I had a correct 33.6V, so the charger shouldn’t be the issue.
After that I plugged my voltmeter directly onto my board charging port (And it’s danregous af omg), touched the two poles by mistake and created a sympatic spark, I though I burned the bms at this time. Then I plugged back the charger to see if everything was still ok and it was charging again, I left it again for like 30 minutes and it charged up to 100% without problem like before.
What happened ? It’s really strange that shorting the charging port solved the problem so I’m asking you to be sure that I havn’t got any problem !
Do you have photos? Which BMS is it? Does the battery voltage change if you flex it? Are there burn marks anywhere? Can you pull apart any solder joints? Did you try a new charge jack?
There is actually some little burn marks inside of the charging port but they must be coming from last evening shorting, looking like this
Didn’t tried to change the charging port because I don’t have the time rn, I still have some of them if needed tho but since this one is working it might be ok.
What do the fuse could do on my issue by the way ?
It sounds like your BMS read one of the P groups as fully charged and shut the charging circuit off. You probably have a P group with a loose cell in it or a bad connection.
So basically you probably have a bad connection in the pack somewhere and just picking it up and moving it around fixed It.
I’m in 8S1P so if a cell die I would have a voltage loose and I wouldn’t have 33.6V fully charged, so it’s not this but a bad connection seems logic to me, than’s guys !
Charger port shorted as the charger was plugged in. The contacts melted into each other… Scary! I believe the port was already slightly damaged, so maybe the positive pin was pushed towards the negative outer body as the plug was pushed in.
