Solar container lithium battery pack has low voltage in several strings

Can a lithium ion battery pack have multiple strings?

Whenever possible, using a single string of lithium cells is usually the preferred configuration for a lithium ion battery pack as it is the lowest cost and simplest. However, sometimes it may be necessary to use multiple strings of cells. Here are a few reasons that parallel strings may be necessary:

How many volts are in a battery pack?

If each cell is 10 amp hours and 3.3 volts, the battery pack above would be 10 amp hours and 26.4 volts (3.3 volts x 8 cells). For this setup, a BMS capable of monitoring 8 cells in series is necessary. Lithium cells can almost always be paralleled directly together to essentially create a larger cell.

Why does a battery pack have a different state of charge?

Additionally, because no two cells are exactly the same, different currents will flow through each battery pack due to differing internal resistances, creating difference in state of charge between the two strings.

Should a battery pack be paralleled?

Paralleling strings together greatly increases the complexity of managing the battery pack and should be avoided unless there is a specific reason to use this configuration. In this setup, each string must essentially be treated as its own battery pack for a variety of reasons. In a below example, 2 strings of 8 cells each are placed in parallel.