What is the best balance voltage for lithium battery pack

If you built a lithium-ion battery and its capacity is not what you expect, then you more than likely have a balance issue. While it's true that cells connected in parallel will find their own natural balance, the same is not true for cells wired in series. Battery cells in series have no way of transferring energy between one another.

In Li-ion batteries which have very low self-discharge and therefore accumulative unbalance per cycle is usually less than 0.1%, bypass current of internal FETs is sufficient to keep the pack continuously balanced.

Battery balancing is one of the core functions of a BMS. Here are two mainly types of battery balancing: active balancing and passive balancing. The main difference between them is if they will waste battery energy or not. Active Balancing= transfers energy from high voltage cell to another cell with low voltage.

When battery packs are built with multiple cells in series, cell balancing becomes an issue. Cell balance occurs when all the individual cells in series have the same capacity, and as a result, the same voltage. This is not a concern for cells in parallel since parallel cells will balance each other with mutually applied voltage.

Whether you are new to battery building or a seasoned professional, it's totally normal to not know how to balance a lithium battery pack. Most of the time when building a battery, as long as you use a decent BMS, it will balance the pack for you over time. The problem is, this can take a very, very long time.

In general, battery balancing methods can be categorized into the following types: Passive balancing dissipates excess energy from higher-charged cells as heat, while active balancing employs a switch matrix and transformer to transfer energy between individual cells.