Can a 36 volt golf cart run on 3 12 car batteries?

Golf carts run off of what are called deep-cycle batteries. Although they look similar to normal car batteries, deep-cycle batteries serve a completely different purpose. While both are lead-acid based, deep-cycle batteries provide a steady current over a long period of time, whereas car batteries provide a very large current over a short period of time. This is because golf carts, like other electric vehicles, derive all their power from their batteries. so the answer is no

car batteries are not designed for constant power drain... they are designed to start up the engine and that is it - after that the alternator takes over... sure wired properly you can get 36VDC out of 3 car batteries, but they would not be efficient in holding the charge...

you would need deep cycle batteries (such as those used in trailers, and RVs) if you were to use them for an electric vehicle like a golf cart...