JoeBhoy wrote:

I have an old Compaq presarion laptop battery which is still in the
packaging.
I was wondering - is there a time limit to how long these things can keep -
this ones about 5 years old. Mint condition though.

They don't take very kindly to going as flat as this one's likely to be:
there's a possibility that one (or more) of the cells will no longer
hold charge, having become reverse-polarised. Unlikely to blow up when
you put it on charge, though, so suck-it-and-see (assuming you still
have the relevant charger!) is fair enough. For future reference, it's
better to put unused 'spare' rechargeable packs on charge a couple of
times a year than to leave them in their Original Packaging...