I have a 1996 club car with 36 volt batteries. I was asking a local golf cart shop how I can increase the power since the cart seems to really slow down on any type of incline or hill. They said I could add 2 48 volt batteries and 4 36 volt batteries and that would give me more power on hills, while still allow me to use the same 36v charger. 

I'd like to know if there is any truth about this, pros? cons? The batteries in the cart are 5 years old as well so we would need new batteries soon. Just want to make sure we have all our info straight. Thanks for any suggestions or feedback.