lith-ion battery charging wire placement

[billrabinowitz]

I have a wheel chair with a lith-ion battery. it does not take a charge . I opened it and found the charging port black wire has come off. the red is still attached. problem is there are 3 leads , 2 on the outer edge, 1 in the center, to which lead does the black wire attach.
thanks
I have pictures if I can load them

[Simon]

Please do not double post the same question as it causes a lot of confusion.