What is a 12v deep cycle group 29 supposed to read when full? I bought a new trickle charger last week and after 3 days on my battery, which was only 30-40% drained, it still wasn't charged up. So I bought a much better speed charge that displays info and has several charge modes. I hook it up and it read around 12 volts, I turn it on charge and within a hour it is above 13 , and it was on the medium setting. When it hit 14 I started getting nervouse and shut it down, even though it said it was only 76% done with it's cycle.