I've got a Honda 4013 that I got used at a good price and I had to replace the battery in June. Recently I ran into some electrical trouble and it won't start. I started troubleshooting with the battery and it seems that it will not hold a full charge. Most 12V batteries I have had generally hold more than 13V when new. It is a U1 type rated at 365A/300CCA, so it's not bottom of the line.
When I hook mine up to the truck to charge, after 15-20 minutes it seems to top out at around 12.4-12.8V. As soon as I remove it from the jumpers and put the meter on it I can watch it drop 0.01V per second. To be clear, that's just sitting on the ground with no load. Sometimes the drain slows down, but it finally settles in at around 11.9V, and holds there, even after a couple of days. I've done this test three times.
I took it back to the shop where I bought it and explained my attempts to charge it to the owner. He took it in the back to "have it tested" and brought it back and said it was fine but it just needed to be charged because it was only showing 11.9V (which I had just told him. Duh!). I don't really trust him. His employees are nice, but he reminds me of several salesmen I have worked with over the years who will say anything to make a sale, and say anything to keep from have to do warranty work or exchanges. I have not had the chance to take it to any of the auto parts stores that do battery testing.
Am I not charging it long enough or do I likely have a bad cell? I have to get this settled before I can do any more troubleshooting. (I suspect the starter, but we'll see.)