What is the shelf life of a new unused battery

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  • Updated 4 years ago
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If I buy several pieces of equipment with batteries and save a battery without using it how long can it be stored and still function properly. 1yr, 2yrs, indefinetly???
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Posted 4 years ago

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Blue Angel, Champion

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John, the simple answer will be pretty much what SCDC said... store in a cool dry place and don't worry about it*. (*asterisk explained below)

If you want to take the red pill and dive head first into the rabbit hole, Lithium Ion battery packs and cells are an interesting technology.

From the Wikipedia page on Lithium Ion batteries (under "Degredation"):


"Degradation is strongly temperature-dependent; increasing if stored or used at higher temperatures. High charge levels and elevated temperatures (whether from charging or ambient air) hasten capacity loss. Carbon anodes generate heat when in use. Batteries may be refrigerated to reduce temperature effects."

So if we invert what they're saying about high temperatures and high charge levels, storing cells at lower temperatures and lower charge levels will reduce degradation. Ego does recommend storing batteries above 0C/32F, however.

Another interesting read is this paper from Inspired Energy regarding their thithium packs, as it makes reference to the pack electronics and how they affect battery storage:


They mention that their packs go into an extended "Storage Mode" once the cells discharge below a certain point, and at that point the electronics draw an almost insignificant amount of power.

I haven't read anything concrete from Ego to confirm this, but I would assume the Ego packs do something similar once they go into their programmed "Long Term Storage Mode" (this happens automatically if the pack sits unused for a period of longer than 30 days, whether on the shelf, in a tool or on a charger).

If the pack is kept in a cool dry place, it will automatically enter long term storage mode and go into a self preservation state.

*Ego reccomends charging their packs once every six months when not in use. My personal belief is, they recommend this so the battery is not left un-used for years and years on end, risking an over-discharge condition. However, I do believe that this would take a LONG time to occur, and their products are certainly designed to sit in the retail packaging for longer than six months between manufacture and first use.

Long story short: Take SCDC's advice above and don't sweat it. :-)