It is not uncommon for the charge lead connector to get damaged (or completely gone) when running on the track. Keep in mind it can become dangerous if the broken wires get in touch with one another! You must stop using the battery immediately, and use tape to separate them so to get them isolated securely.
To have a replacement connector properly wired, first you must realized that the wire color scheme can differ depending on the manufacturer (see the comparison photo below) and that a proper wiring scheme may have to be devised out of confusion:
The general guideline for a 2S pack is that the left most wire always goes to the battery’s positive while the right most wire stays with the battery’s negative. The middle wire goes to the battery’s positive-to-negative connection.
You may also find cuts on the wire and you better use tape to seal the cuts before putting everything back together.
