LIFePO4 batteries - interesting challenges
In another thread I detailed what I was doing to upgrade batteries to LIFePO4. Thought I'd raise a new thread for some challenges I'm facing in case someone searches on it in the future. I have 4 1...
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LittleBill wrote:
i am going to back peddle on my comments.
my comments were mostly around li-ion which is what i use. looking at how life are composed the final voltage does matter, there is no charge controller inside most of these battery types simply a balancer lvc etc..
14.4 puts u at about 3.6v per cell which is max.
13.6 puts you at 3.4.
if you didn't want to run max somewhere around 14.0-14.2 i would go( really depends on if you need the higher capacity)
SOC is practically impossible from what i am reading, the voltage drop curve is practically straight
you would be better off basing it on AH removed and using that for SOC, instead of voltage. this is done by running down to LVDC.
sorry the misdirection earlier, we all learn something new every day.
link on DOD cycle life
Thanks for the info, I am definitely learning as I go! I am indeed basing off the amps out/in, as you say voltage is essentially useless. I have bulk set to 14.4 but may ease off to 14.2 as I don't need the extra oomph and I don't think it gives me much.
I got the discharge curve on my LIFePO4's, they run straight until you hit about 20% SOC remaining @ 12.8V, at which point it tails off pretty quickly (12V @ 10%, then precipitously steep decline from there).
