Should You Charge Your Phone Every Day or Just When It's Emp

The answer is complicated, since it depends on the particular product in question, explains Suzanne Foster Porter of Ecos, a Colorado-based consulting company that works on energy efficiency of battery chargers, in everything from MP3 players to forklifts. While some older battery chargers continue to draw power from the grid even when the battery is fully charged, more modern chargers are smarter: They basically turn off once the device is done charging. "But it's difficult to tell which kind you have, since manufacturers aren't required to tell consumers," says Porter.

That could change soon: Porter says Energy Star plans to develop a new label for charger efficiency. (There's already this one , but it only applies to a narrow range of products.) Until then, you can follow these general guidelines:
• When plugged into a charger, products that use nickel-cadmium and nickel-metal hydride batteries often draw power even when they're fully charged.
• But modern lithium-ion batteries, the kind in most laptops and cell phones, are generally very good at knowing when a product is fully charged.

The charge-every-day method is also better for the battery than running it down and doing a "deep charge" every once in a while, says Isidor Buchmann, CEO of Cadex, a company in British Columbia that manufacturs and analyzes battery chargers. Daily charging puts less stress on the battery and thus makes it last longer. A few other tips from Buchmann for prolonging the life of lithium-ion batteries: More about lithium-ion battery chemistry and more handy tips
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