BFL13 wrote:
The Battery U link has a charge time graph (scroll down) that has what I need to make a time comparison to do a "0-90". Obviously the "90-100" times are of great interest, but I don't have that for FLA. Their graph does go to 100 on the capacity curve.
I will use my ugly graph figures without inflicting the graph on folks again, unless you all insist. I have it for a 55 amper on 220AH doing a 50-90 which is a 25% charging rate, so that makes it convenient. I just need to do it in proportion for a 100AH batt, easy! Same times at the 25% rate doing 25 amps on 100AH as 55 amps on 220AH.
The FLA Bulk ends at 72% SOC and tapers to 90%. the Batt U graph shows the time for when the capacity reaches 90% on their 100AH batt. It shows Bulk ending at 60% SOC then amps taper.
(Howls of outrage from the usual suspects!--so take that up with Batt U , not me)
So FLA first:
0-72AH at 25 amps = 2.88 hr = 173 min
72-90AH tapering = 86 min
Total time 0-90 = 259 min = 4.32 hr
Now the LFP:
0-60 at 100 amps = .6 hr = 36 min
60-90 tapering amps = 39 min
Total time 0-90 = 75 min = 1.25 hr and 4.32/1.25 = 3.46 times faster
It would look worse for the FLA if we added the 90-100 part.
What about a 40-90 though, perhaps more typical of camping?
FLA : 40-72 at 25 amps = 1.28 hr = 77 min
72-90 still 86 min
Total = 163 min = 2.72 hr
LFP: 40-60 at 100 amps = 12 min
60-90 still 39 min
Total = 51 min = .85 hr and 2.72/.85 = 3.2 times faster
So if you added the 90-100 times it would be more like the 4 times faster claim for a 0-100 looks like. (if anybody would ever do that with an FLA!)
EDIT--in real life an RVer might have a 100a charger and be used to doing 50-90s with his 460AH bank of FLAs. He might wonder how much gen time he could save getting the same AH restored (that matched his AH usage) if he switched to LFP.
Now he can't use the 4 times faster as with 1C vs .25C. He has to do a whole set of calculating to see how much gen time he would save with how many AH of LFP instead of his 460AH of LFP, assuming he will still use his 100a charger.
non of this makes any sence, first off your link doesnt work so I cant see the graph, also why are you tapering at 60% for the LFP, they will go from 0 to ~ 97% on bulk with no tapering. you only need a single stage charger if you are happy with this and you can still get it to 100% with that same single stage charger. if you are using a 1C charge rate you can charge a LFP in 1 hour maybe a couple min longer. this isnt conjectur, its in the manufactures specs for the LFP cells. the only issue a camper will have is getting enough charger power to hit that 1C rate, which if you build any significant battery you wont do it. so a 280 AH at 0.25C is quite possible, that would be 70 Amps of charging so a larger converter would do it or a combanation of converter and solar, or larger solar. I get 22 amps off my one panel camper so if I add another I am up to 44 on a good day. so realy it is about how fast can you replace you overnight use. my one panel does it by noon (havent sat and watched to see when I hit 100%, and it would do that with LFP or FLA batteries. by switching to LFP I go from two 6V GC to one battery that is a little smaller than one of the GC and weighs about 1/3 of what was is there now.oh and has 2.8 times the usable AH. so how does this benifit me, well it lets me move the battery into a indoor space that isnt used right now (so no more worries about tempature) it will free up an out door storage space so I will be able to put some stuff in there instead of in the door on the floor. and if I do hit a run of bad weather, I have the capacity to go about a week with no sun...
Steve
