Time for a new battery?

[TCNashville]

I'm still using the original Excide battery that came with the camper and it's now 6 1/2 years old. Our last trip was 3 weeks ago and when I unhooked the camper I took a voltage reading and it was 12.8 volts. Pretty good I thought. A week later I went down to the storage facility and the battery was at 12.56 volts. Took another reading today and it's down to 12.51 volts. I have a battery cutoff switch at the battery which I installed a few years ago so no parasitic drain. I leave the battery installed all summer but remove it during the winter where it's kept on a battery tender. Is this normal to lose 2.9 volts in a 3 week period? I'm thinking I got my money's worth out of this but hoping it'll last 2 more trips we have planned this year. Also thinking I would replace it with an AGM no maintenance battery so I won't have to mess with adding distilled water. We don't boondock. My converter is a Progressive Dynamics 4045KA with charge wizard. Will that converter be ok for an AGM battery? Thanks, Terry

[grimeshaus]

Move that decimal point back, that's .29 volts and I'd be happy with that. Your battery is getting a little old though.

[jimp]

For a 6 y/o battery, still in good shape. I would use it this yr and then replace over the winter or in spring when you find a good deal on your preferred battery. I've got some 5 y/o batteries in my boat that last all day or however long I fish on a particular day. I know I need to replace those but I'm looking at 4 batteries in the boat.