I bought a laptop a while ago and then I decided to use it as a stationary PC, so I took out the battery, put it in a thin box and stored it in a closet, The battery had some charge on it(I don't remember how much),the battery has been stored for almost two years... Is it ok to keep storing it in the closet ? for how long can I keep it there ? the battery has been stored for almost two years...
I also have two other portable laptops and I want to order backup batteries for them...Can I store the backup batteries that I order forever ? or do I have to charge them from time to time ?
You cannot store them forever, once there is literally 0% power inside you won't be able to charge it anymore. It's fine to use laptop without a battery but you should charge it once in a while, like once a year I would say.
It's a difficult question t oanswer, because it can depend on the composition of the battery, the quality of its manufacture, etc.
Essentially Lithium Ion batteries work best when they are used, storing them for long periods of time without charging them can result in damage to the battery cells. I'd suggest that for long term storage, make sure you actually use the battery every so often, but store it after it is charged. Lithium Ion batteries in particular operate best when they are charged and you can start to incur damage to the battery if you fully discharge it or don't charge it for a long time.
While Lithium Ion batteries are not susceptible to the same "Memory" issues that NiCad batteries are, cumulative damage to the battery can reduce it's effectiveness to the point where the battery can indicate a full charge then shut off while indicating that it still has a 90%+ charge remaining.
In short over time, the ability of the materials used in the battery to retain the charge does become increasingly impaired and that's a problem shared by all batteries. It sounds like you are storing it correctly, but you should use it occasionally to keep its cells active.
Batteries have shelf life, meaning they degrade even sitting on the shelf, so don't buy backup batteries, thinking, what they will go up in price later? The latest is, for long term storage, charge them up to ~55% b4r placing on shelf. Cannot help u with external charging.