Clip+ v2 strange battery use

[kasskas]

Hello,
Two months ago I decided to try a dev built of Rockbox (cannot remember which one), after which my battery life was improved to around 24h of playback. After a month or so, decided to try another iteration, but that one drooped my battery life to like 3h and installing previous one (will edit to exact built) didn't change, and player now days only after 3h of use. Could it be that the rockbox built damaged the battery? I have ordered a new one, but at first I want to find out why old one died. I attach my battery bench file. 

[saratoga]

Your battery drops from 97% charge to 74% in 2.5 minutes. I think that means that the battery has died and needs to be replaced.

I don't think how the battery charge is handled has changed in many years, so I doubt what build you were running makes any difference. Probably the battery reached the end of its life.

[kasskas]

well the reason why I am concerned, is that it died in a month or so. From one folding 24h charge to 3h. Quite a steep drop

[saratoga]

That is fairly common for lithium batteries. There are other possible things that could have failed as well (charger IC), but an 8 year old lithium battery is already extremely old and most likely to fail.

[asymsucon]

Quality Li-Ion cells can last well over 10 years, but they have to be stored at 40% charge (3.8V open circuit), not 100%. One of my Panasonic 5200mAh laptop packs still has over 92% of original capacity since 2006.
It's how you treat them.

Fortunately, exchanging battery in Clip+ isn't that difficult, and you'll find the replacement in higher capacity too.