Cell Spy 8 Voltage Checker

The Cell Spy 8 is an easy-to-use device that can show you the condition of your battery packs while also serving as a battery balancer and servo tester. Simply plug in your battery and the Cell Spy 8 will display a variety of diagnostic information including total pack voltage, individual cell voltages, percentage of remaining battery capacity, degree of cell voltage imbalance and much more. A few quick button presses will also activate discharging or battery balancing modes. The Cell Spy 8 works with the following battery types:

LiPo (2S-8S, can test 1S when an additional NiMH or NiCd battery is connected)
Li-Ion (2S-8S)
LiFe (2S-8S)
Li-HV (2S-8S)
NiCd (4S-8S)
NiMH (4S-8S)

To use the servo testing function, just connect your servo and a 4-cell NiMH or NiCad pack and you can toggle between manual, automatic and centering tests.