Need A Spare Battery?
You sure do!
Even if your digital cameras usage is sporadic and just around home, there is nothing worse than being caught out with a depleted battery when the good shots just start coming. Birthday parties do not slow down for you.
Even worse - going away for a memorable vacation and running your battery down half-way through the first day. The rest of the tour bus passengers will not wait near a mains outlet while you try to recharge your one and only battery...
Also consider - if you are travelling there may be periods when even you cannot get to a mains outlet for electricity. The wilds of Africa and Canberra are notorious for this. If you have a spare battery you can coast past this electricity-free day and still get photos.
Better still - two spare batteries - extra capacity never goes amiss, and you can leave a depleted one on the charger in your hotel room while you shoot through the day.
They can be had from the original camera manufacturer or from after-market sources. Not a great expense set against the cost of travel and the safety of having a camera that works when you see that perfect shot.