Shore Power. Charging 2 12v Battle Born Batteries wired in series on a 24 volt solar system

[John Frum]

For what its worth I just checked a time lapse video I have of charging a 3s12p battery with cc=4.73 amps and cv=12.3 volts.
the CC phase ended when the pack voltage indicated 11.5 volts and the charger voltage indicated 12.0.

 

[SolarRat]

For what its worth I just checked a time lapse video I have of charging a 3s12p battery with cc=4.73 amps and cv=12.3 volts.
the CC phase ended when the pack voltage indicated 11.5 volts and the charger voltage indicated 12.0.

That particular charger switched when it saw 12v. But it didn't know if the cells were 4v each, or if they just equaled 12v...ie 4.1v, 3.5v. 4.4v...

Likewise, a 48v charger on 4 BB's has no idea when each battery is ready for the CV stage. A 4 bank charger does, because it charges each battery separately. That is why I think 4 batteries in series, no matter what brand or what internal BMS it has, should have a "master" BMS between them, actively monitoring and balancing. Or, just use a multi bank charger. Also, with a MBC, you can easily add new batteries to your "old" bank without worrying about them charging differently.

 

[John Frum]

That particular charger switched when it saw 12v. But it didn't know if the cells were 3v each, or if they just equaled 12v...ie 4v, 2v, 3.5v, 2.5v....

I believe it switched when the batteries could not draw the full current.
EDIT: I guess that means the internal resistance for the pack is kinda high.