HELP!!! BMS? Lithium battery pack common fault mobility scooter

[tomcolesy]

Hey guys. First post for me.

I currently have quite a few battery packs that are fitted into mobility scooters. The pack is self is in a box with 2 fittings. It is also fitted with a BMS. One for the load of the scooter and the other for the charger. I am getting a reading on the charger port but the load is showing nothing. Both ports if connected to a charger is allowing the pack to charge. It seems that this is a common fault on these batteries as I have had this on numerous occasion. What I have found strange in the past is I have removed the BMS and charged the pack. After refitting the BMS it has worked. Other times it hasn't. I am unsure if it is the BMS at fault or it is just me being stupid. I'm really stuck at the moment and any input would be greatly appreciated.

Thanks in advance
Tom

[Swake]

Have you switched it off and back on?
Our crystal balls aren't working anymore. How do you think we can help with the massive amount of information you provide?
What scooter? What battery? What charger? What BMS? configuration? Schematic? Pics?

[abdulbadii]

have ensured all are cleans, every conductive connections is 100% unrusted ?
good if image inserted here

[SMdude]

Check that all cells in the pack are reading the same voltage. If you have a cell gang that is down/up in voltage, the BMS will not allow it to run.

Typically if a cell gang is out of balance with the rest, there will be a weak cell amongst them.
When making/rebuilding packs, you need to make sure the ESR of the cell gangs match. And for this reason, you cannot just replace a bad cell.