solar
I just want to operate a residential fridge thru my inverter. How many 12v batteries and will a 100w panel work?
Forum Discussion
BFL13 wrote:
I don't think you have done the calculations for that.
You keep seeing this claim about faster charging with LFP, but nobody explains how to do that. EG this "4 times the rate" claim that will reduce gen time.
To me that must mean restoring four times the AH in the same time that it would take with FLAs . Or same AH in 1/4 the time.
If you now have four 6s at 460AH and a 75 amp charger powered by a 2200w gen (like my set-up), that means you can do a "50-90" (184AH) in about 3 hours.
To do that in 1/4 the time- 45 minutes-that means charging at 245 amps. (184 x 60/45) So first you need a 245 amp charger or combination of chargers, and a generator to run that.
I doubt that is what was meant! So how about some realistic numbers with a realistic RV set-up for chargers and gen sizes and the LFP bank vs the four 6s, a 75 amper, and a 2200w gen?
EDIT--ok, say I had the same set-up only with LFP so no amps tapering. It all gets done at 75 amps. 184/75 is 2 hrs , 27 min. so I would save 33 minutes (from 3 hours) of gen time. Not quite the same as "four times faster" is it?
How about I do a 50-80 with my four 6s? Now it all gets done at 75 amps where amps start to taper at 80% SOC. 150AH in two hours. Swap to LFP and--oops--still 150AH in two hours.
you can charge at a 1C rate with LFP, so if you have a 486 ah battery bank and you are setting up your system to be compatable with a generator why wouldnt you get a larger charger? aside from they get ecpensive above a point but relisticly a 150 amp charger wouldnet be out of the question if you were setting up for Li in the first place, so 150 in one hour. or if you have money to spend you could set that bank up with a 300 watt charger and 150 in 30 min. that is the big advantage of LFP, you build to pound the amps in when you have them available. so hugly oversized solar, or chargers and so on. not saying most people do this so in 80% of the cases your example may be right, the LA may have some aceptance limitations but for the most part it will be close.
Steve
