Lithium Ion Cell Balancing

Active cell balancing is an amazing way to handle the cell balancing problem but in terms of system integration and optimization this approach takes a hit on many fronts like cost and complexity.

Lithium ion cell balancing.

Figure 1 illustrates a five cell balancing circuit with 1 ω resistors setting the transfer ratio which is the ratio of the imbalance voltage v cell v avg to the balancing current i cell. Different algorithms of cell balancing are often discussed when multiple serial cells are used in a battery pack for particular device. The means used to perform cell balancing typically include by. The lithium ion battery balancing act more and more the world is running on lithium ion batteries.

It is significant progressively productive in light of the fact that energy is moved to the necessary spot. True balancing brings the battery into perfect balance on every charge cycle. The worst thing that can happen is thermal runaway. The ltc3300 is a standalone bidirectional flyback controller for lithium and lifepo4 batteries that provides up to 10a of balancing current.

As we know lithium cells are very sensitive to overcharging and over discharging. The improved effectiveness is the requirement for extra parts at a greater expense. Unfortunately cells from many manufacturers have significant cell to cell variations. A problem arises when a cell in a string loses capacity or develops elevated self discharge.

How do you balance a lithium ion battery. With improved battery cells and new cell chemistry the battery variation is stabilizing. Adding cell balancing is beneficial especially as the pack ages and the performance of each cell decreases at its own pace. Equalizing the socs of the various cells in a battery.

Quality li ion cells have uniform capacity and low self discharge when new. Since it is bidirectional charge from any selected cell can be transferred at high efficiency to or from 12 or more adjacent cells. Safety hazards from overcharged cells li ion batteries have very high electric energy concentrated in small volume. In a pack of four cells if one cell is 3 5v while the other are 3 2v the charge will charging all the cells together since they are in series and it will charge the 3 5v cell to more than recommended voltage since the other batteries are still require charging.

For batteries of relatively large capacity typically 20 ah or more balancing currents up to 1 a are desirable in order to minimize the time to. In this arena lithium ion battery technology is fast becoming the standard. Active cell balancing it uses capacitive or inductive charge carrying to move charge between battery cells. Lithium ion batteries will never be out of balance again true balancing is a completely new approach to cell balancing.