You have 'x' number of total recharge cycles in any one battery.
If you want to use them up with 1/2 charges ..... be my guest.
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http://www.pbase.com/sfleming
Too many cameras ... not nearly enough photography.
Yes you should NOT charge every time you think its a little low.
The battery may have 500 charge cycles for example. If you keep
charging every time to up it, you will lower the lifespan of the
battery. I did this with a G2 and the battery was worthless in
about 8 months. The 10D battery should give you hundreds of photos
and reviewing per charge, and when the battery indicator shows low
charge, you still have the ability to take over 50 photos safely.
If you wish, contact The Battery Barn, or a similar store and they
will confirm this point. Why waste a battery that should last for a
very long time.