To update the thread... we manufacturer truck mounted cattle feed dispensers. They run off 12 volt and pull around 20 amps while running empty. The battery was charged all night. I hooked the battery up and let the feeder run no more than 30 minutes. When I hooked the tester to the battery, I didn't even have to load test it. It was only showing 9.5 volts. It's a 24 month old, AGM battery. I called the place where I got it and they have an 18 month warranty. Had I known that to start with, I would never have bought it to begin with.
I did a lot of reading about Lithiums last night. Watched a few YouTube videos too. One video talked in depth about Lithium technology and the guy said that many bass pro's used Miller Tech Lithiums. I looked them up last night and it's a business owned by 2 guys in Ohio. Their website has both their cell phone numbers listed. I called and talked with one of them for a while this afternoon and I ordered one. They have a 5 year full warranty. No proration like a lead battery.