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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