XTAR VC4S Charger
The VC4S by XTAR is, in our opinion, the best battery charger on the market. On top of its main features of displaying battery health and condition the VC4S can determine the type of battery installed, read the internal resistance of the batteries and come with a quick and easy green/red indicator when the batteries are charging or fully charged.
Make us of the VC4S "Grade mode" which will fully charge, discharge and recharge the batteries to thoroughly test the grade of your batteries and highlight the real battery capacity. The charger can also revive over-discharged old batteries.
It is powered by a micro-USB connection and is compatible with all 5V USB outlets and will charge a wide array of batteries including 18650 and 21700.