BFL13 wrote:
LFP specs say 1C is possible but recommend 0.5C. FLA can be charged at .3C, not just .25C. What is "valid"? 1C vs .25C or .5C vs .3C?
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one huge thing your missing is that your going of sales info. no seller who has to honor warenty is going to say, go ahead and charge at 1C all you want. the prismatic cells I am looking at are rated up to 5C as long as you have a solution for the heat it will create. they can do 1C all day long. so 1C charge rate will completly refill the battery from 0 to 100 in 1 hour. but lets try a different angle here to see if you are just looking at it differently. lets talk usabal AH and keep that as the comparason.
so I have four 235ah 6V batteries in my 5th wheel right now which gives me 235 usable AH. lets say I have a LFP that is 235AH so that is 235 usable at a 0.25C charge rate it will take me 4 hours to recharge my LFP, I can tell you from experiance with that charge rate it takes a lot longer than that to charge the Golf cart batteries, we are looking 6 to 8 hours and that is only to 80% now are the batteries acepting the full charge, nope I have a temprature compensated system so if the temp starts climbing the amps are cut down to prevent dammage to the batteries. it does kick in charging my FLA batteries, but at that rate it wouldent cut in on the LFP so if you factor in the adsorption which could be another 4 to 6 hours to get up to 100 then ya the same system will replace the AH drawn about 4 times faster.
there does come a point where if you drop the charge low enough though they would be closer togeather in time, but if you go and spend the money on LFP why would you not upgrade the rest of your system to take advantage of them?
to me it seams you are basing everything on having a 20 to 40 amp charger on a larger fla bank. I have a 40Amp converter in my camper right now, but as soonn as the LFP battery gets installed that is going up to a 90 amp. can I use 90 amps right now with 210 AH of GC batteries... nope it will just taper amps like crazy so I left it at 40 for now.
so your trying to compare a setup that shouldnt be compared. if I ran a genny instead of solar, which to me if you are spending the money to reduce genny use why wouldnt you add solar and scrap that noisy thing in the first place ;) solar is now dirt cheep, for 600 cdn I bought and installed a complete 325 amp split cell 24volt pannel, the wires, the controler and some other knick nacks. a second panel will only be 200.00 which I will add when I switch to LFP. so right now I have 210 AH (105 usable) with up to 24 amps charging from solar and up to 40 amps from my converter. when I put in the 280AH usable LFP battery and add a second panel and chage out the charge section of my converter, I will have up to 50amps from my solar, and 90 amps from the converter. so doing the same type of camping replacing the used capacity every day will be very fast.
its all relitive, they can accept a higher charge rate so take advantage of it. if I went SiO2, I would never be able to add a second panel and I would have to restrict the output of my converter to 25 amps, every battery tye will have advantages or disadvantages its just how you view them and what your willing to do to take advantage of the good things or minimize the not so good things...
Steve
