If there is an internal break then it goes from battery voltage to nothing under load. Test voltage on post directly while under load. Got 11 or 12 volts? Not your battery.
This is NOT a sure thing. .........The battery in my case worked FINE for awhile, until I CAUGHT it "dead" and checked voltage right at the posts. When it DID work you could load test the you-know-what out of it and it would be "fine."
