I too am interested in LiFeP batteries. I think we need some more information on charge/discharge cycles. I've bits and pieces, but there must be some solid data from Panasonic or one of the other LiFeP manufacturers. Such as,
Recommended charge cycle Maximum discharge rate Low voltage disconnect Also I expect all of the CC manufacturers are thinking about LiFeP or similar Li technology. Maybe if one of us has a friend at Outback Power, Morningstar, Midnite Solar, we could find out more. - Peter Peter T. Parrish, Ph.D. President, SolarGnosis 1107 Fair Oaks Ave. Suite 351 South Pasadena, CA 91030 (323) 839-6108 [email protected] From: RE-wrenches [mailto:[email protected]] On Behalf Of Daniel Young Sent: Monday, August 17, 2015 2:29 PM To: 'RE-wrenches' Subject: [RE-wrenches] Lithium Iron Phosphate Hello Wrenches, I've been trying to think through how I can mate some lower cost charge controllers (prostar 15A 24v PWM units, or the new 30A Midnite solar Brat) to some 8s LiFePo battery banks. As I understand it, lithium batteries meant to be charged to around 3.65V per cell (29.2V for the 8 cell bank) and then the charge is terminated, not put into a float mode. Assuming I use a PCM to protect the batteries, so that each cell has a balancing function and also over/under voltage protection. Would the battery bank accept a simple charge controller that in essence, charged to 3.65V/cell, then backed down to a float voltage that was lower than it's resting voltage, say 3.3V/cell. In theory at that voltage, there would be little/no charge current going to the batteries. Or would the cells still take in a small amount of power at these voltages and start to overcharge/degrade? Again, I'd plan to have a full PCM circuit protecting cells and balancing them, but I'd like to have a good way to charge the batteries with solar (right now I'm shooting for using a 72cell module and 24V nominal LiFePo battery stack, so maybe there is another way that I can use, but I've not decided to buy any batteries I am ok with accidently blowing up if I'm wrongJ). With Regards, Daniel Young, NABCEP Certified PV Installation ProfessionalTM: Cert #031508-90
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