The OP could measure the charger output first to see if it's working right. About 42V for a 36V system, and 54V for a 48V system.Besides, I believe he stuck the key into the charger port on the battery, not the charger plug from the charger.
I once totally wasted my time replacing a BMS in a battery when the problem was the wire to the charger plug had broken off. On top of that, the BMS I put in leaked voltage to the outputs when it was off. I had waited too long to install it, so the return period was over. I bought a new BMS that was worse, as it blew up. The seller pulled a fast one on me, sweet talking me until the Paypal dispute period expired, and I was stuck again. A third BMS fnally worked. They're only $20, so I wasted $60. A good learning experience. What if I had learned about the Paypal dispute window with a $300 purchase.
Last edited by Doc_Wui; 05-09-21 at 11:38 PM.