I just purchased the FMA Direct cell pro 4s balance charger. And I am impressed. I paid like 90 bucks for the charger pc adapter, two battery adapters(one for e-flite and one for Thunder pro). This charger lets you watch the voltages in each cell and lets you adjust amperage.[link=http://www.fmadirect.com/products.htm?cat=45&nid=4]Cell pro 4s[/link]. This so far has been a good little and inexpensive charger.