Reed,
The no warranty is a problem for me since the lithium batteries are about $0.35 a watt-hr (so I have an issue with ordering $3500 worth of batteries as-is)
Lifeline gives a 1 year warranty and a longer pro-rated warranty. The Lifeline GPL-6CT AGM batteries are 6V 300AH and are $388.95 with free shipping from Impact Battery. I wouldn't do a 12V system (I am going for 24V) but if you did it would be 12V at 1200AH. Battery cost would be $3111.60 and there is no need for a BMS. At a 50% DoD you would get 1000 cycles give or take. They are 90 pounds each according to the spec sheet.
The LiFePO4 is attractive because of the weight, greater depth of discharge, and the cycle life is probably longer (I say probably as I do not know anyone who has more than 1000 cycles on LiFePO4 as it is relatively new). If the sellers of the battery had enough confidence to provide a real warranty, I would have enough confidence to buy LiFePO4.
