Fried BMS and charger?

loafin_about

10 µW
Joined
Jul 6, 2022
Messages
5
Hi all, I'm looking for some advice on troubleshooting steps on what I think is now a dead charger and a dead BMS, both due to my stupidity! I have been given a DIY ebike running a no-name 48v battery pack and a charger - both from EM3ev I think. One question, and an explanation.
BMS first - when trying to replace the broken charger connector I shorted the two wires with a big spark. Discharge wires still show steady 47.8V but 0.1V at charger connection. Charger doesn't recognise the load and doesn't push charge in.  I have tried to reset the BMS by briefly charging through the discharge port but no luck. My next step is/was to dismantle casing and remove BMS briefly then charge and reattach. However, there are two small wires coming out of pack adjacent to charging wires, presumably BMS, which is joined via a loop. See photo below black plug with thin red wire loop. Looking for confirmation this is a BMS on/off switch connector and I can remove the loop effectively turning off the BMS rather than physically removing BMS to reset?IMG-3668.jpg

Secondly - charger which is a 'LTX LT250' and puts out 5A. In another moment of stupidity in trying to reset the BMS I swapped the positive and negative wires and connected to battery! Big spark and now the 240V charger doesn't even power on. There is a 240V fuse on 240V inlet side of the circuit board but it hasn't failed (multimeter test) so presumably the circuit board is fried somewhere on the 52V output side. Will try and borrow a new charger to help troubleshoot the BMS. 

Thanks in advance, and yep, I know this all results from mucking about without thinking enough! Hence the question about the BMS loop rather than just blindly disconnecting or hacking the shrink wrap apart!
 
E-HP said:
A lot of EM3EV packs use a smart bluetooth BMS. Are you able to "see" the BMS when you open the bluetooth setting on your phone?

Hi E-HP, thanks for the speedy reply. That lead me down a whole world I didn’t know - Bluetooth connected BMS.
No, can’t see the BMS or any unknown Bluetooth devices on either my iOS device or partner’s android device. I haven’t installed the EM3ev app given I couldn’t see it.
I did read the BMS needs to be on to be visible but the beyond turning the key switch I can’t turn BMS on/off without borrowing a charger presumably.
Cheers
 
Just to update.
After getting a new charger, EM3ev customer service ( excellent by the way) helped identify the BMS is dead but all cells are fine. New BMS on the way and back on the bike soon!
 
loafin_about said:
Just to update.
After getting a new charger, EM3ev customer service ( excellent by the way) helped identify the BMS is dead but all cells are fine. New BMS on the way and back on the bike soon!

Great outcome, and customer service! :bigthumb:
 
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