Is my laptop battery still usable?

Question

I had a li ion laptop battery about 2 years ago, there's a safety test sticker dated July 2015 on it. I've never had it in my laptop, it's just been sitting in storage up until now. My current one is on it's way out so will this stored one still be good and safe to use? I put it in my laptop and it won't turn on with it, but i wanted to ask before applying a charge to it just in case it could be dangerous or something.

Answer 1

If the battery gets too low on charge (sitting on a shelf) it could need time to charge so leaving it plugged in for a while may work to bring it back to life or unfortunately you need to buy another. As the battery hasn't had any physical damage, it should be OK to leave plugged in.

Answer 2

The battery has its own internal processor that determines if it will allow the battery to "operate"--to allow it to charge or to provide power. If it detects the cells are too low in power, it says to itself, "at least one of my cell's charge value is so low and depleted, that if I allow charging, that cell will draw so much power it will overheat, and might cause a fire or blow up. So I won't allow any charging, [or battery use]".

Unfortunately, when this happens, the only "fix" is to get control of that part of the battery, or it will never allow any charging. Unless they built in communication access, you won't be able to, even if the manufacturer can. I've got a non-functioning battery for a drill in this condition, and I must open the case and work on the cells individually.

When storing a LiIon, never store it depleted for this reason. It very slowly looses its charge, which can then fall below the "go-nogo" charge decision. But, don't store it at 100% either, since this is very bad for the battery--it grows little copper fingers which bypass more and more of the electrolyte, until eventually, it won't hold a charge at all.