Making your own LiPo packs is not difficult — it only requires a little care. To make a 2-Cell (2S) pack, you’ll need 2 identical LiPo cells and a female 3-pin JST-XH connector. You can buy the connectors pre-wired, or save a little money and buy raw connectors and a crimp tool and do it all from scratch.
On the connector shown at left, the red wire will be connected to the positive terminal on one cell, and the black wire will be connected to the negative terminal on the second battery.
Next, the negative terminal from the first battery is connected to the positive terminal of the second battery. Then the blue wire from the center pin on the connector is also connected to the positive terminal on the second battery. This wire is used by the charger to monitor and control the voltage in the second cell during charging.
When building your pack, be very careful to not short the cells out. If you do, it’s possible you’ll ruin the cell(s) or worse.