Most of the time it warns you if you are about to do something silly like try and charge a 2s on 4s or have connected battery round wrong way. If you only have a. 50w charger you will not be able to charge that. 6600mah at full rate it will only charge 5a max so about hour and half need 80w or higher. My charger is 200w a channel and can charge 2 x 4 s at 10a together