I have never had a cart under warranty, they cost real money, maybe someday
I did have a 2000 Par Car until recently and never had to replace the charger. The charger did stop working once. I called Lester Electrical and a super nice gentleman helped me find that the relay was the issue. Inexpensive part and easy fix. I cannot say enough about a company that takes a support call for a 10 year old charger
Not sure why you are asking about the relationship of charger and battery? From my reading the only time you may need to change charger is you go from a wet battery to a gel battery as the gel charge at different rates (but I could be wrong on that).