3S are 3 banks that are connected in series. You need to charge EACH jar SEPARATELY . I insert 2 needles into the balancing connector (nearby)-this is one bank and I connect wires from any telephone charging at 5 volts.I put the battery in the frying pan (suddenly it pours) . It is necessary to constantly watch with a voltmeter how much voltage is on the needles, periodically disconnecting from the charge. It is enough to charge up to 3.7 volts (I usually charge up to 3.8 volts) each jar and computer charging "will see the battery and start charging it in LiPo mode. It is absolutely IMPOSSIBLE to charge a battery that is deeply discharged through a power plug : when one of the cans is recharged, a fire with abundant smoke may occur.I use such a restored battery in radio control. It does not have excellent indicators of the new .