Best way to take care of extra notebook battery?

[Spoooon]

Should I just store it somewhere completely drained until the battery that I'm using now starts dying? Or should I alternate batteries every month or so?

 

[eriqesque]

Well if your gonna store it and I am assuming it's a Li-Ion battery you will want
to store it an a cool place at about 40% charge.
That being said batteries are consumable so they go bad after a while just
sitting around and not being used.
So it may be just as well to use the thing or sell it.