TP4056 is designed for charging single cell (3.7V) LiPo battery. Your 7.4V is a 2-cell LiPo. You should get a proper charger which can balance-charge 2-cell LiPo. Otherwise, you can still charge a 2-cell LiPo by charging one cell at a time using TP4056 module by using the small 3 wires connector. Be extra careful of the polarity