The battery has three wires. We only have +- controllers. Please help me.

[sunned]

First of all, please understand the awkwardness of English. I used a translator. I want to replace my controller because it's broken. First of all, my battery line is the 3rd line using the mt30 connector. A line from the battery other than the P + P- line is connected to the controller. But most of the time, only two lines were supposed to be connected. I found a controller connecting 3 lines. The controller was connected to the vcc. Does anyone know what my controller 3s function is? Is there a place to solder where I can replace this line?

[eee291]

If the new controller is aftermarket and only needs + and - then you can ignore the 3s wire, unless it needs a signal there to activate the BMS but I have no idea.
If it doesn't work just install a aftermarket BMS on the battery as well and you should be good to go.