@robby - Have you actually looked at the graph you posted? The three blue lines are showing the capacity over time at 30°C, with SoC at 30%, 65%, and - you guessed it - 100%. So yeah, if you
STORE LFP cells at 60°C or even 45°C your capacity is going to drop off, and it will drop off more if they are at 100% SoC. The temperature is by far the bigger impact. At 30°C there is virtually no difference between the 30%, 65%, and 100% SoC.
I have said on numerous occasions that Temperature is the biggest factor. If you look at that graph which says it deals with
LiFePo4 you can see that the Capacity at 100% SOC on day one is about 14.7Ah and by day 80 it is roughly 14.5Ah. The interesting part is when you get to about day 380 the capacity gets to 14.25 Ah and then makes a significant drop to 14Ah by day 465. This equates to a 1.77% drop in capacity over an 85 day period! Now if I am optimistic and assume that no more big drops happen and it travels along that same line going out, then in 1340 days or 3.7 Years I will have a greater than 20% drop in capacity.
(20% / 1.77%) x 85days + 380 days = 1340days / 365 days = 3.7 Years.
I am not a battery expert so if someone else see's some error in the calculations or maybe I am not seeing something on the graph, please point it out.
I don't have the time to find it right now, but one of the papers you posted as "evidence" of how bat 100% SoC was also had quite a bit about the fact that much of the SoC-related loss of capacity is recoverable, simply by cycling the batteries. You seem to have not read that either.
Please point to the recovery of capacity I did not see that mentioned. That 190 Page paper is not something that I plan to read the whole of!
What I did see was that periodic cycling does keep the capacity from dropping.
Finally, I think that everything you have been citing (again, I don't have time right now to read all this junk) has been about STORAGE which is not what most people will do. The cells may be in float at 3.35V for some time, even potentially for several weeks. Then they will get cycled again. I believe you making comments that people who don't agree with you will have to replace their cells in a couple of years is not helpful.
I agree, most people do not use LiFePo4 for storage but the question was bought up about having batteries fully charged and on Standby which is the same thing as Storage. I said in another post that periodic cycling like twice monthly according to one of the papers can prevent this issue.
This thread was pretty useful for quite a while, but now we have over two pages of you arguing a point that I'm not sure matters to most of us. The fact that you started out talking about laptops and cell phones also lessens the value of the thread. How about let's just assume that you are right and it should be noted, but that the actual impact and importance is subject to specific conditions and everyone can factor it as they see fit.
The reason Laptops and Cell phones got into this argument is because the papers that
@Mr-Sandman presented from
@Will Prowse use Lithium Ion as some of the examples. Almost every document I can find on the subject Intertwines Li-Ion and LiFepo4 in the same paper.
I cycle my batteries and honestly I do not care what anyone does with theirs. I am only answering the questions that kept on being asked as best as I could.
To answer the last question that
@Sojourner1 asked, I do not see a full cycle as going up the knee to 3.65 Volts per cell, that is not a good idea as useful charging ends at 54.5 Volts. I charge to 54.5 and discharge to 51.4V. This can vary with battery chemistry but these are the values that company recommends for my batteries and they have worked well for me.
