Update: The Canon BP-511 Battery Pack has been replaced by the Canon BP-511A Battery Pack.
The BP-511 is a Lithium-Ion battery - as maintenance-free as the current crop of digital camera batteries get. The manual simply tells you to use them and charge them as you desire.
My personal recommendation is to have at least two Canon BP-511 Battery Packs. Keep one in the camera, keep the other(s) fully charged in your bag - ready for immediate use. Giving each battery a complete discharge/charge cycle during each use cannot be bad.
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