Hello,
I have a 3p4s config of 280Ah cells making up my battery.
I have significant cell voltages differences (0,18) so balancing needs to be done.
Can anyone give me an idea at what capacity the REC Active BMS is able to do this balancing?
How many Amps can the BMS redirect from the highest to the lowest cell?
Is there a formula, is it constant?
Thx
Carl
The Active BMS wil balance at up to 2.5 amps per cell. Balancing will start at BMIN setpoint, usually around 3.4 volts. You don't want to set it lower because the mid range charge voltage of LFP cells is so linear it is difficult to calculate exact charge capacity of each individual cell. By starting your balance further up, where charge % is more accurately read, you can acheive a much better cell balance. With a large pack like yours you may want to leave it on charge for a couple of days to bring it up to BMIN and allow the cycle to start
Here is the sequence from the manual.
Balancing START Voltage (BMIN):
If errors 2, 4, 5, 8, 10, 12 are not present and the highest cell voltage rises above
Balance START voltage and current is > 0.2 A (charging stage) the BMS initiates
balancing algorithm. A weighted cell voltage average is determined including
cells DC internal resistance. Balancing algorithm calculates the voltage above
which the cells are balanced. The lowest cell voltage is taken into account
determining balancing voltage.
Balancing END Voltage (BVOL):
If errors 2, 4, 5, 8, 10, 12 are not present any cell is above balance END voltage
are balanced regardless the battery pack current.
I slowly see the lowest voltage rising. From my calculations, the balancing current per cell can only be max 0,5A.
Whatever, if it works in the end, it is ok for me...
