Joe,
Think your issure is that battery was designed for a UPS, not as a power soure are a starter. I tried batteries from a battery store, not good results. The price is great. Able to start your engine, questionable. Wasn’t designed to be rattled around in a kart. Very short life cycle. Comet lists an orginal replacement battery. It will only be heavier on your wallet. But it will turn over you engine and it will last.