Boston Gal's Open Wallet

Getting back to your question, start with the assumption that your computer will operate exactly the same whether or not it's plugged into the wall. In that case, you're probably better off staying plugged in, because energy is lost in the process of charging the battery, storing the electricity, and then powering the computer from the battery. A report (PDF) prepared by the Natural Resources Defense Council five years ago estimated that running a laptop from AC power is about 20 percent more energy-efficient than doing it off a battery. Even if battery charging systems have improved since then, common sense suggests that using AC power requires less energy. (Some laptop users contend that keeping a laptop plugged in damages the life of the battery. If so, this would be a tougher call, since batteries require an awful lot of energy to manufacture, and there's an environmental cost to recycling a spent one. Different manufacturers give slightly different answers: Lenovo and Dell told the Lantern your battery should be fine if your computer stays plugged in; HP says you should remove the battery if you are running on AC power for weeks at a time; and Apple suggests you should unplug and run off the battery every once in a while. Check your manual, but the Lantern thinks you should be OK using AC power most of the time.)

Labels: Saving Energy