DIY battery pack BMS question

[Mike Amick]

Building my first battery pack for a E-bike conversion.

It's a 13s 6p 48v using this kit from Aliexpress:

https://www.aliexpress.com/item/13S...ml?spm=2114.10010108.1000023.7.1f016857xVnICA

Finished it up this afternoon and when I read the voltage from the BMS it read 34v, but from opposite
ends of the battery it reads 53v.

Whats going on ?

 

[tomjasz]

May have a cold solder joint. Check the tabs to the BMS. Kind of a funky design at first view. You 53v is nearly a full pack voltage,

 

[Mike Amick]

All 13 strings progress nicely up to the 52v. I heard somewhere that the bms has to be
for lack of a better term programed. And that might just mean .. like you said cycling it.

I actually wont have my charger for a day or so, I will try that when I get it.

thanks

 

[harryS]

Don't see an on/off circuit on the board, If it had a place for an on/off switch, sometimes that needs to be flipped to get the BMS started after you connect everything. I just hooked up an Annpower BMS and that was the case. I closed the switch. Nothing happen. I swore and flipped it again. Then it worked. But you don't have a switch.

Also didn't see where a charger plug would connect, but your BMS doesn't appear to have any balance circuits anyway. Balance current not being mentioned in the specs is the first clue..

Did you measure the voltages at the edge of the B1-B13 pads on the circuit board, rather than on top of the nickel strips. I'm sure that what Thomas means by bad solder joints.

 

[Mike Amick]

Ok a person on another forum found some feedback about this board and apparently it
does not do balancing. So It's good I found that out before I put it into service. So will be
looking for a balancing 13s 48v bms.

Thanks for all the help.

Mike