@lee321987 wrote:
<snip>
@ @ 40% @ 100%
charge. charge.
Capacity Capacity
Storage lost per lost per
Temperature year year
25C 4% 20%
<snip>
Ah, but since the 100% battery starts with so much more, it takes quite a while for the higher discharge _rate_ to leave the battery with less charge than the 40% one.
After 100% 40%
Year
1 80 38
2 64 37
3 51 35
4 41 34
5 33 33
6 26 31
etc
So, it takes _5 years_ for the higher discharge rate to lower the 100% battery to the same charge as the 40% battery. After that the 100% battery really goes to hell, but nobody is thinking about 5 year neglected storage, I hope.
But, the real story, I think, is not the self discharge rate, but the charge on the battery. Li-Ion are happier operating at less than full charge. IIRC, I’ve read that the lives of batteries that are only 1/2 charged (to 3.9v) are twice that of batteries fully charged (to 4.2v).
So, yes, you’re better off storing at 40%, assuming there is some way to tell that the charge is 40%. I also have a Fuze in reserve and this discussion prompts me to do this: I am going to use this reserve Fuze until the battery indicator show 2 bars. Then store it and periodically check the charge. When it gets to 1 bar, I’ll charge it, but only to 2 bars, and put it back on the shelf.
Bob
