The Elite Power Solutions Battery Balancer -- a simple, low cost way to assure that all the battery cells in a series are equally charged. When charging, it places a small load on the battery when it is charged to 3.7V or more. When charging stops, it brings the voltage down to the same point on all the cells and turns off. For lithium batteries only. Available for 40, 60, 90, 160 and 200 Ah cells.