On Sun, Dec 25, 2016 at 6:21 AM, RussellMc wrote: > DOD% Cycles > 100 1000 2.7 years ar 1 cycle per day at 100% capacity > 64 2000 > 43 4000 > 40 4500 > 30 6200 > 20 8500 23 years at 1 cycle per day > *AT 20% capacity !!!!* > Russell, thanks a lot for this information; I read through all your links. These numbers above are very disappointing. The Wikipedia page on NiFe ( https://en.wikipedia.org/wiki/Nickel%E2%80%93iron_battery) states 30-50 year typical lifespan and that "Repeated deep discharge does not reduce life significantly", which seems to conflict with the numbers from the brochure you linked. Any idea why that is? Does the construction of these cells affect their durability this much? In any case, I'd prefer not to have to worry about watering them, so it looks like I'm going to be getting some of these LiFeYPO4 cells ( http://en.winston-battery.com/index.php/products/power-battery/item/wb-lyp4= 0aha?category_id=3D176) which are popular with the EV folks. Apparently they have excellent cycle life and very good calendar life. If they last 15 years, hopefully technology will improve by the time they need to be replaced. --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .