Never had a problem with my surplus AGM DEKA 150Ah + Telcom battery... 12.88 to 12.90V depending on the temps in the garage where it's stored. 10 months from date of manufacture. As stated by Landyacht, cycle it, stir the chemistry up with a good 50 to 70% SOC discharge, and then top it up at 14.4V until it holds a low current that no longer is decreasing. This battery might not power a big inverter, but for my 21 ft travel trailer, it's the Energizer Bunny. Just keeps on going, and going, and going. I don't draw a lot of amps off of it, but I am sure I could run 2 days, probably 3 between a generator recharge at 2 hours, and 150w solar panel on a sunny day for the rest of the 3rd day to top it off, fully. It stores well, doesn't lose voltage very fast or discharge very fast at all in storage, when fully disconnected.
