Does a battery still lose some of its life cycle sitting in a garage unused and on a charger?

[moh.vze.com 276]

Does an XS Power Battery still lose some of its life overtime if I don't use it and just leave it on the trickle charge for 1 year? I have 3 new XS Power batteries but am debating if I should install them now or a year later. I only bought them because of the 20% eBay discount. I was gonna save the batteries unused and buy more batteries later and use them all at once so that they are all in new conditions.

Also, these don't have manufacture dates on them do they? Sometimes I wonder how many years they've been sitting on standby in the warehouse from these retailers.