Make a three-string battery pack

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.

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.

How does a battery pack work?

Since the charging is handled and controlled by the charger on each string, each battery pack is only responsible for providing discharge current to the common DC bus. This completely eliminates the possibility of eddy currents and of damage to the charge equipment since each charger is controlled individually by each string's BMS.

Can a Li-ion cell be used as a battery pack?

Li-ion cells are increasingly used as battery packs for many applications due to their high energy density and rechargeable characteristics. However, we must link a Li-ion cell with a BMS to safeguard the circuit from being destroyed or reducing the cell's life.

How do I balance charge the battery pack?

To balance charge the battery pack, an extra set of wires must be attached to the battery pack with a JST XH female connector. To seal the battery pack for safety and sturdiness, we use a 100mm PVC Heat Shrink Sleeve and shrink it around the battery pack. After it's done, the battery pack will look as indicated below.