Battery Post repair suggestions

[scooterman]

So in 2014 when I got tis cart it had one of the battery post that was shorted out and damaged but the seller assured me it was solid. Well this weekend I was cleaning the post and it twisted off. I've searched and watched a few repair videos, some guys drill and tap and some just drill it out. If you look at the attached pic, the area when the post twisted off looks open, I don't think it is leaking but not sure, what should I do with that and does anyone have a stud particular for this or should I just find a brass toilet flange stud?

Any input would be appreciated, the cart is at my camp three hours away so i want to go back prepared so i can fix it right.

Thanks in advance.