It would be great to have a range of battery balancing boards from Pololu. There are a multitude of cheap chinese boards out there, but I prefer having something so important from a reputable manufacturer with proper datasheets. There are also a multitude of (fairly expensive) full BMS systems out there that are overkill for many applications. Some applications just need a reliable way to ensure battery balancing without any extras.
Battery balancing boards are not very complex: As lithium battery packs get used the voltage of the different cells in a pack will slowly drift apart because the cells have slightly different capacities because of manufacturing tolerances. A balance board will need to be connected to all the cells and detect a difference in the cells. It would then funnel charge between the different cells to get them back to equilibrium.
Different operating modes are thinkable:
- detect voltage differences of 0.1v or more between two neighboring cells and start to balance these two cells until the difference is below 0.03v for example.
- detect voltage differences of 0.1v or more between any cells and start to balance the highest to the lowest cell until the difference is below 0.03v
- any more complex algorithms
A big downside to offering such boards is the sheer number of variants needed. Boards for battery pack sizes of 2s, 3s, 4s, 5s, 6s, 8s, 12s, 16s and 24s are needed at least, as those are the most common configurations. Having two variants for each, one with a max balance current of ~1A and one with a max balance current of >5A would be useful as well. That’s 18 variants already. Theoretically one could just use many 2s boards for larger battery packs and connect them between every neighboring cell pair, that would reduce the variants to 2 for the proposed 1A and >5A.
Well, just something for you guys to think about.
A sensible operating voltage range would be 1.5 - 4.5 V, which covers all currently available lithium chemistries.