Shelf life of an unused phone battery?

I bought a (used) Samsung Galaxy phone on eBay about three weeks ago, but it seemed that the battery was useless. It would lose all charge within hours, so I purchased a new battery (also via eBay) which FINALLY arrived yesterday.

In the meantime, the original battery has decided to play nice and is keeping charged for a few days, depending upon use.

I’m guessing that I am going to need the new one sooner or later, but wondering what to do with it in the meantime. Can I just leave it untouched until needed, or do I need to ‘charge’ it, then leave it alone?

tl/dr What’s the shelf life of an unused battery?

I have two batteries for my cell phone. I switch them out each month.

I don’t have a cite. I recall reading that rechargeable batteries need to be in service. Getting charged and discharged. Helps fight off the memory effect.

Lithium ion batteries are small, light, and have a high energy density for their size. This makes them great for things like your Samsung Galaxy.

Unfortunately, lithium ion batteries don’t age well. No matter how you treat them, they tend to die an early death.

Heat kills lithium ion batteries. Store it someplace cool, like your fridge. Don’t freeze it though.

Don’t completely charge the battery as this will increase the aging rate. Don’t completely discharge it either, as this will also kill the battery.

Ideally, charge it to a little under half charged and stick it in your fridge. That’s about the best you can do with it.

NiCads and NiMH batteries are different than lithium ion. It doesn’t hurt NiCads to completely discharge them before storing them. You don’t want to completely drain NiMH batteries though.

NiMH batteries need to be exercised or they start to self destruct. You don’t want to stick them on a shelf and leave them sit for a year. You should charge them up and discharge them (not completely) at least once every few months. NiCads on the other hand can sit for a very long time, but you’ll want them to be at least mostly discharged or they won’t age well either.

Heat isn’t as deadly to NiMH and NiCads as it is to Lithium Ion batteries, but NiMH and NiCads do best in the fridge in the long run.

40% charge is the ‘sweet spot’ for Li-ion longevity, along with cool but not cold. I would recommend getting it to 50% charge (to allow for self discharge to 40%) and put it in the fridge, if you can use the weaker of the 2 batteries, save the stronger one in this condition, if not then do what you need to do.

Thanks folks.

So if I’ve got this right, I roughly half-charge the new battery and bung it in the fridge until my other battery dies?

I think even I (a complete and utter Luddite) can manage to execute* this* process.