Just wanted to share my experience on resolving a 2s lipo performance issue by replacing the connector on it.

I have a Gensace 800mah 40C 2S lipo which is used to fly 2 inch (88mm) micro quad with 1104 7000kv motors.
The battery is 1 year old and done 100+ flights so far. There is no puffing on the battery. I always keep it in storage charge after flying and never over discharged it.

Off late I have started seeing the voltage SAG become so bad. (full charged battery immediately dropping to 7.0V on flight).
And after flight, the connector was so hot. Upon further inspection found that the ground pin on the JST connector (on battery) had a burned mark.

I replaced the JST connector with a new one. The original battery wire is 20AWG and the connector I replaced have 24AWG. (I did not have JST connector without wire)

Tested the battery and voltage SAG is reduced to normal level. And the connector is no longer getting hot.