This connector will allow you to link two batteries together. 

In doing so, you won't have to worry about switching between batteries when one has run out of power.

With both batteries linked together, you can charge them at the same time via the controller.

 

*DISCLAIMER* Before linking both batteries together, it is recommended they are at equal levels of charge. Therefore, we suggest draining both batteries independently and then link them together to charge as one via the joystick controller port.