Possibly because they are just sitting and not being used. Not that all will go bad but non use is not always good either. I have some non use lithium too but have not checked in a long time. Im sure I'll run into that issue myself when I come to finally check them. Its kind of like someone pressing on your skin for years without letting up. Your skin breaks down and damage occurs. Im sure batteries are similar. Use them and they should do you well. I remember one person who I believe still recommends you not buy your batteries until right before you put them into use. I believe this would be good practice and one that many don't do.Bought CALB ca's about 5 yrs ago and had some 4 out of 45 cells come up with high resistance out of spec and replaced by CALB on warranty. I have now 4 more with resistance higher than 1.2 milliohms (spec is .7 or lower) with one of those 4 at 2.2 milliohms. These are all figures reported by Orion BMS.
Anybody have any insight into why this happens and what a recommended course of action to take? buy 4 new cells? look for used cells? It seems that especially the highest resistance cell is cutting into usable range. I still have resting charge of above 3.2 on my best cell when BMS is cutting back 1238 controller output.
I guess this is a good question because I think I have asked it 3 times with very little response.
Thanks in advance