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Don't keep fully charged Li-Ion in long term storage, they tend to bulge
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RoGeorge:
Many of the used phone-batteries (Li-Ion) left fully charged about a year ago have bulged meanwhile.  I didn't know that in long term storage Li-Ion rechargeable should be half empty.  :-\

Searched about this only after noticing this month how most of the old batteries decided to swollen during the last year, while they were just sitting there after they were all fully charged about a year ago.  The Internet says there are some charges that even have a "storage" charging mode.  None of my phones or camera chargers have such a for-storage charging mode.

I'm still not sure if a fully charged Li-Ion is supposed to bulge if left fully vcharged for a long time.  Though, those batteries otherwise survived without problems for 5-10 years discharged (and disconnected).

Anybody else noticed storing Li-Ion fully charged will inflate the battery?
Infraviolet:
I always thought the trouble was if you put them in to storage nearly empty, that way they self-drain slowly and have less time before they go below the minimum voltage threshold. I had though the ideal was 75% charged, but anything in the 50% to 100% range was usually ok.
Gyro:
~40% seems to be the general consensus for storage. There have been quite a few threads over the years.
SiliconWizard:
Whether it ends up bulging really depends on the battery. But storing one fully charged is a sure way of killing it over time. Every LiPo battery that I stored fully charged died after 2-3 years. The sweet spot for long-term storage depends. Can be anywhere from 40% to 80% SOC depending on battery and studies. Also recharge them to the storage SOC on a regular basis to avoid them getting to a dangerous low SOC by self-discharge.

I have had bulging on a LiPo battery that I used as power back-up in some device. It was a 1000 mAh LiPo IIRC, and the charge current was set at 100 mA. The charging circuit would keep it fully charged at all times (only with a small hysteresis.) The bulging started after about 2 years of operation. It was pretty bad.
Gyro:
The Logitech Harmony One remote would keep its Lipo at 100% SOC whilst in its table tray. The battery would swell so badly that in many case, it was necessary to dismantle the remote to get the 'removeable' battery out of its slot. The FAQ said that this was normal behaviour!

P.S. I still have mine. It sits on the side table and only gets charged overnight when the battery indicator shows low. The cheap replacement  battery still lasts more than a week between charges, and after several years (5+ irrc), no bulging.
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