LiFePo4 lithium battery charging questions

otrfun wrote:

StirCrazy wrote:
ya he also mentiond that people thing LFP is more finiky than it actual is with the capacity usage and charging. I learned about the float, and to set it for your normal charge voltage as most people don't let there LFP equalize long enough to actavate the cell balancing. never thought that would be an issue.

What do you define as "normal charge voltage" or "float voltage" for a lifepo4?

When you say "most people don't let their LFP equalize long enough to activate cell balancing", what you do mean exactly? As 3tons mentioned, lifep4's do not require equalizing. Are you saying there's a specific voltage necessary to activate cell balancing? And/or a specific amount of time is necessary to accomplish cell balancing?

cell ballancing won't happen untill you are full, so by setting equalization and float the same as charge voltage you will allow more time for top ballancing. Im not talking days but maybe an hour or two extra time for the top balancing process depending on your bank size.

most people just charge them and as soon as they reach 100% they turn off the charger because so many people are scard of letting them sit at 100% becasue of myths propagatd that are intended for storage and maybe the issue is the definition of "storage" to me if you are camping you are never in a storage situation. and when I got home from a trip I would probably give it a day on the charger to make sure it was top ballanced then unplug it if I was going out again next week, and not worry about it being at 100%. or run somthing to bring it down to 90% then plug it in again the night before I am leaving to make sure its full for the trip. to me storage is realy when we are talking in terms of months. so lets say I am working a ton of OT at work for the next two months and I know I am not going camping. run the batteries down to 70 or 80% and unplug. but then before a trip I am charging them the night before to 100% again.

the whole issue is there is a lot of sterio type carry overs from Nickle mettal hydride and other forms of Li batteries that people assume apply to LFP also. some may verry well still apply but not in the same ways. the old 20 to 80% operating range isnt one of them. yes I would say to avoid using the bottom 10% but there is no reason not to go to 100%, just don't leave it there for long term storage. and this 90% range will increase the cycles you'll get out of your pack because thr 3000 to 4000ish is based on 100% cycling. and if you think about it if you fully cycle your batteries twice per week at 3000 cycles thats going to last your 28 years. even if you cycle it 6 days a week that will still last you just hy of 10 years, and remember that 3000 cycles isnt a measure of when the battery will stop working but rather when it has degraded down to only having 80% of its original campground. beyond that it may run for another 20 years at a slower degradation as that first 20 % is the fastest and it slows down as it goes. so realy if you have a 400AH bank and you only use say 200 of it, in 28 years you will only have a 320AH bank and as long as you havent abused it to cause dammage and its still normal cycling it will peobably last you a lot longer than most of us will live at that level. so yes if your going to use them in the winter find a way to keep them warm, if the usage its self dosen't do it, charge them to 100% often to keep them ballanced and when you are "storing" take some of the charge out so its not sitting full. I still have to look into this one more and find out exactly how thats harmfull or if it even is in all conditions, maybe its fine in the summer and only bad in the winter of vise versa.

Steve