vcocciolo
New member
Hi group.
I hope you can give me some hint because it's driving me crazy!
First of all I purchase a Bafang BBS02 kit for my bike with its 10 Ah battery and everything was fine until the battery has been stolen so I purchase a new one. Still from Aliexpress.
The one in this photo:
This battery immediately gave me problems because its run out after only 30Km of moderate assistance 100 W - 150 W
I measured on a bench, charging and discharging with the "Watt's Up monitor", and in effect the only available energy its around 5 Ah instead of 17.5 Ah
The fully charged battery voltage is 54.6 V but on the discharge the BMS shut down at 48 V (as expected?) giving me only 5 Ah
I changed the BMS (13s7p 30A) but same result!
I teared apart the blue plastic cover to expose the battery cells. It reveals 91 (13x7) 18650 cells 3.7V for 2.5 Ah :
With the battery data sheet I discovered an important fact:
A fully charged battery has 4.2V that for a 13s battery pack means 4.2x13=54.6V that is exactly the charging voltage I have
A fully discharged battery has 2.5V that means 2.5Vx13=39V
So, to receive the promised 17.5 Ah, the battery needs to be discharged at 39V but my BMS (correctly?) shuts the current at 48V so it's only 5Ah
Please, be kind, to give me some hints. I'm also afraid to purchase another pack and have the same problem.
I'm quite good with electronics so nothing will be wasted!
Regards
The Battery Pack exposed :
The old BMS removed :
The new BMS :
The battery at the end of the charging process:
I hope you can give me some hint because it's driving me crazy!
First of all I purchase a Bafang BBS02 kit for my bike with its 10 Ah battery and everything was fine until the battery has been stolen so I purchase a new one. Still from Aliexpress.
The one in this photo:
This battery immediately gave me problems because its run out after only 30Km of moderate assistance 100 W - 150 W
I measured on a bench, charging and discharging with the "Watt's Up monitor", and in effect the only available energy its around 5 Ah instead of 17.5 Ah
The fully charged battery voltage is 54.6 V but on the discharge the BMS shut down at 48 V (as expected?) giving me only 5 Ah
I changed the BMS (13s7p 30A) but same result!
I teared apart the blue plastic cover to expose the battery cells. It reveals 91 (13x7) 18650 cells 3.7V for 2.5 Ah :
With the battery data sheet I discovered an important fact:
A fully charged battery has 4.2V that for a 13s battery pack means 4.2x13=54.6V that is exactly the charging voltage I have
A fully discharged battery has 2.5V that means 2.5Vx13=39V
So, to receive the promised 17.5 Ah, the battery needs to be discharged at 39V but my BMS (correctly?) shuts the current at 48V so it's only 5Ah
Please, be kind, to give me some hints. I'm also afraid to purchase another pack and have the same problem.
I'm quite good with electronics so nothing will be wasted!
Regards
The Battery Pack exposed :
The old BMS removed :
The new BMS :
The battery at the end of the charging process: