Older battery performance January 04, 2016, 08:35:40 pm Yahoo Message Number: 157933I have 4 6 Volt AGM batteries which were installed along with four aprox 100 watt solar panels by AM solar 9 years ago last October. They seam to work pretty well but I am wondering how much better a new set of batteries would perform (faster charge, slower discharge?). I think AM solar told me some people get as much as 11 years from AGM batteries, and one person I met said up to 20 years (? ? ? ? )My Xantrex battery monitor (I think it might be a "XBM", but sold in 2006) does not display any value for CEF (charge efficiancy factor), which is some indication of the ratio of how much energy you get back compared to put in when charging the batteries. Xantrex manual says this is about 90% with new batteries and degrades over time. Xantrex told me over a year ago that my monitor is out of support and they would say nothing more. Perhaps my monitor has a problem, or my CEF is so degraded it can't calculate any more?Thanks for any ideas,Jay Carlson