cochise49 wrote:
Twice in the past decade, I have taken our rig in to the shop where it stayed for 4 and 5 months respectively. Both times, the AGM house batteries failed while there. The batteries were not charged while stored/waiting for parts.Only times I replaced them.
This is not normal. A fully charged and healthy AGM should still retain more than 60% of charge after 5 months of storage with open contacts. Either they were not fully charged before, or were already not healthy, or were not completely disconnected from the trailer loads. Or - poorly made from the beginning.
There is more to maintaining AGM than depth of cycle. Lifeline in particular recommends using VERY high charging currents and warns that the life will shorten if you don't. Most other AGM brands specify only maximum current but not minimum. Another thing with Lifeline is that they can and sometimes should be equalized/conditioned, which is something that other brands don't mention. Like Mex said - read the manual.
Reports that such and such AGM lasted 8,9,10 etc years, don't tell much. A battey life is measured in cycles. If you run only 60 cycles a year because you only camp in summer on weekends, it will last many years. That's why I said earlier that the question "how long do AGM last" is impossible to answer.
