Deligreen Balancer 4s unit $140
Deligreen Balancer's transfer energy from high volt cells to low volt cells, 24 /7, whenever there is a voltage difference between cells. Multiple units are connected together in series for larger series strings. Download manual.
3.65v charger $32
Used as single cell charging.
Red LED - Charging
Green LED - Finished charging.
Can be left connected to battery cell permanently. Does not discharge the cell.
Single cell balance charger example