Short: I need to become proficient in the care and feeding and optimal use of LiFePO4/ LiFeYPO4 batteries in the 40 - 400 Ah (maybe more) range. This is mainly a notification that I'm delving into this area and an invitation to anyone who knows anything on the subject or who can just tell an excessively interesting story to comment. As I know more I'll comment on what I learn if it seems useful. Initial 'playthings' are 2 x Sinopoly (son of Thundersky) 12V, 40 Ah LiFePO4 or LiFeYPO4 depending which blurb you read. _________________ More ... As part of a project I have just acquired two Simopoly brand 12V nominal, 40 Ah LifePO4 (of LiFeYPO4) batteries. Each of these has 4 x 3.2V cells joined by nostalgia invoking cell to cell straps with bolt on busbars and the 4 cells are strapped together. Thusly http://images.trademe.co.nz/photoserver/full/242923341.jpg I could have bought similarly specified "Winston" LiFePO4 for only slightly more but various factors (including external cell terminal access on Sinopoly to allow balance checking and rebalancing) bised me towards SP for 1st off use. These will be used as a 24V 40 Ah battery with a small grid tied inverter and a 250 Watt 30VDC PV panel as a testbed for "related activities". A DIY MPPT solar controller may happen or the recent kickstarter offering may be acquired. Numerous commercial offerings exist but most don't allow flexibility of battery management and monitoring that I need to learn what I need to know. My aim is to learn how to optimise some mix of whole of life battery capacity / battery lifetime / cost of energy storage / other. Other is always a problem. I'll be glancing briefly at the Suzuki LEAF LiIon cells which at very high cycle lives - although they had some early problems (as one does). There are various LiFePO4 management guidelines available from various manufacturers - with the usual level of contradiction one learns to expect, and uncertainty as just what is inside a given battery. different enough measurable characteristics to raise questions, and a lot more. (eg Winston and Sinopoly both derived from Thundersky but Winston have claimed a substantial jump in cycle lifetime relatively recently and have a higher charhging voltage requirement than Sinopoly. (Winston charge specs look almost like a LiIon being run in a modest way. Not what they claim and I'm far from knowing enough yet to be able to tell.) While small cell LiFePO4 charging is only somewhat puzzling (with some major variations from LiIon), advice of larger cells suggests a much more lead-acid type approach with recommendations for bulk, absorption and float cycles, dire warnings against exceeding various DOD limits, reductions in cycle life with DOD from some suppliers that contradict those from others and much much more. There is a large amount of widely variable material on the ee blogs - e scooters, electric cars, motor homes, off grid community and more. What fun / agh! That should do to start Russell .. Winston & Sinopoly both derived from Thundersky who may still exist as well, there's CALB, GBS, GWL Headway, Lightning Nano (26650 cells), A123 (18650 cells), LiFebat, and then there's BYD. BYD SHOULD be the 600 pound gorilla but may or may not have accessible product. Comparison of Sinopoly, Winston, CALB, GBS, Headway If you believed this you might buy Winston. I bought Sinopoly to start and am not yet aware that it was a bad choice :-). http://auto-elektryczne.com/images/LiFePO4-battery-EV/LiFePO4-battery-price= -parameter-Sinopoly-Winston-CALB-GBS-Headway.pdf --=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 .