Can you add additional parallel groups to BMS?

[YoshiMoshi]

Say for example a BMS comes with a battery case that allows for a 5S2P configuration, due to limitations of the dimensions of the case. For example in plastic cases for power tool battery packs.
Can I take this same BMS that came with the 5S2P case and wire it up in a 5S3P configuration, adding a parallel group of cells?
I know the BMS would have the same ratings, same continuous discharge current and so forth.
If I'm willing to live with that, can I add parallel group of cells? I don't see why not.
Note, I'm not suggesting anyone do anything here, I'm simply asking a question only, to understand this concept.

 

[dominik h]

Yes, you can add parallel groups.
Balancing will probably take longer because of the higher capacity.

 

[E-HP]

Say for example a BMS comes with a battery case that allows for a 5S2P configuration, due to limitations of the dimensions of the case. For example in plastic cases for power tool battery packs.
Can I take this same BMS that came with the 5S2P case and wire it up in a 5S3P configuration, adding a parallel group of cells?
I know the BMS would have the same ratings, same continuous discharge current and so forth.
If I'm willing to live with that, can I add parallel group of cells? I don't see why not.
Note, I'm not suggesting anyone do anything here, I'm simply asking a question only, to understand this concept.

5s3p is parallel groups of 3 cells, with each of those groups wired in series, so going to 5s3p would involve adding one cell to each of the 5 existing goup. Is that what you are asking about?

 

[bananu7]

The way it helped to clear it up for me was this: each group of cells connected together sits at the same voltage. Thus, parallel connections equalize voltage, while series connections equalize currents. Since the groups are never of exact same capacity, drawing the same current won't make them sit at the same voltage, potentially allowing a group to drop too low or charge up too high. That's why the BMS measures voltages across self-balancing parallel groups, and equalizes the groups to each other. That way no single cell will have a voltage that's radically out of spec.