cart goes then quits

[mel 2]

cart goes for about 500 feet then dies leave it for about an hour goes another 500 feet again. Batteries are fully charged it is a 36v system and about a 1985 model also the wife left the ignition and lights on for about an hour and half, thats when the problem arose. The cart has a bank of selinods, is it possible the one of them is letting go or is something else heating up and cooling off to cause this problem (also i have a very upset wife lol)