When You say won't crank up for 10 minutes,do you mean that or won't fire up? Whenever troubleshooting electrical problems,the first thing I look for is good grounds,especially when I know the engine has been out. Then go to positive cable connections,and then on to voltage drops, from batt to relay to starter, and batt to interior power distribution. That being ok,check for power coming back out. Sounds like a bad connection overheating. Hank