More common is the instruction to charge them and then run them completely into the ground before recharging at least the first two times, and in some cases the first three times, that you charge them.

When you recharge, you're using up a recharge cycle, and coming one cycle closer to not being able to recharge anymore. Lithium ion and lithium polymer batteries need very different treatment, and often come with instructions to charge the battery every chance you get. With no memory effect, there's no need to run them down, ever. Keep in mind, however, that the best way to maximize its life varies even from one model to another. The rule remains: read the directions that comes with the product.

• Do make a point of storing them in a cool, dry place at normal room temperature.
• Do make sure that the contacts on your rechargeable batteries and in your camera stay clean and make good electrical contact. If they seem dirty, use a pencil eraser to clean them.
• Do make a point of giving them a chance to cool down after recharging instead of popping them into your camera immediately.
• Don't leave batteries — or your camera with them in it — sitting in places like a hot car in direct sunlight for extended periods of time. Heat raises the self-discharge rate — and it isn't a good thing for the electronics inside your camera, either. Nor should you leave them sitting in places like a cold car in an unheated garage in the middle of a New England winter with temperatures at 17 degrees below zero. Cold also drains power quickly.
• Don't try to recharge camcorder batteries in a charger that's not designed for them. Match the charger to the battery type.