I agree the depleted to full test is not valid but that is how they do it to get their 4 x claim. That is where the sales guys get to put "4 times faster" in their ads.
Meaningless when FLA stays above 50% so it loses half the range where it could be taking in high amps. If you started both off at 50%, that is not fair to the LFP.
I don't have a valid comparison to cover all scenarios, because they don't have the same operating SOC ranges for one thing. LFP is faster if you do supply more amps than the FLA can absorb.
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?
Solar is not so clear with its low amps, the FLA can take them in, and the LFP is stuck with the same amps (can't make the sun shine brighter) so hardly any difference. You need to get more panel watts same as you would need a bigger amp charger to exploit the LFP advantage, but if you are getting to full by 2PM most days you might wish to spend your money on something else. Or you might want more battery AH in the same space, or more cycle life. It is all up to the individual and his own scenario.
BTW that BU-409 link was working this morning, I haven't checked it lately.
