Glad the seller looks after you, the last cells i got off ebay like yours tested to 1200 mAh and the last ultra fire cells when discharge in a pair with balance leads connected the charger kept tripping out due to uneven voltage.
With the 2s balance lead the negative goes on the negative of the first battery the positive goes on the positive of the second battery and the one in the middle goes in between the positive and negative of both batteries (middle). Then your main charge leads go on like normal.
This thread might be of interest as it has pictures of what I'm talking about.
https://budgetlightforum.com/t/-/3118
Once the balance lead is connected you will truly see how they pair up when discharging. And maybe this thread below will be of some interest.
https://budgetlightforum.com/t/-/1621
It is good when the radio's have a low voltage warning i use 2.4 spectrum for air and 2.4 futaba for land and water and they have low voltage warning, but a lot of the cheap radios or RTR radios do not just a light, but like i said in my last post I'm sure you know all this i just mentioned it for the sake of others.