Is this one of the Walmart batteries that you referred to? Who makes it? Seems to be a very able power source!This thread got me curious. I have flatlined my batter three times now. I'm talking so low a light wouldn't even glow.
I decided to test my battery. Thanks to amazon points, I bought a tester and emptied the storage bin. The 1 1/2 year old battery that has been abused tested out perfectly healthy. Perhaps the deep-cycle batteries are more resistant than I have assumed.