Chargers are rated by output power. This output power sets what the charger can do as far as current at a give voltage (cell count). What fools a lot is that a 50watt charger is rated for up to 6S (22.2v nominal). What they don't tell you is the charger reduces charge rate to stay under its power limit and although the charger will charge that 6S, it will take literally hours to finish a charge.

If your 4S is a 5000, a 1C charge takes 84watts, so an 80watt charge will not let you do a full 1C (5amp) charge - 80/16.8 = 4.76a will be all the charge current allowed under its 80watt limit. This will increase charging time.

The GT Power (2nd link) is 200watts and would be powerful enough to do a full 1C charge rate. This is a DC charger and will need a separate power supply. I've been using mine since before last Xmas and its been a good charger.


There are some options with AC/DC chargers, but they're more expensive.