The best way to power up your gadgets.

 Amy Wilson

The smoke detector chirps, signaling its battery is dead. Your portable DVD player quits working midflight. Do you reach for the convenient disposable batteries or the everlasting rechargeables? Here’s what to consider (free of charge).

  • A disposable alkaline battery will work twice as long as a rechargeable battery before it needs to be changed. So it makes sense to use disposables for low-drain devices (ones that don’t draw much current), such as smoke detectors, alarm clocks, and remote controls.
  • For energy hogs, including portable DVD players, remote-control toys, and cordless power tools, opt for rechargeable nonalkaline batteries. Although rechargeables have a higher up-front cost (about $30 for four AA batteries and a charger, compared with $3 for four disposable AAs), they can be recharged about 100 times, making them easier on your wallet in the long run, says Tom Reddy, editor of Handbook of Batteries (McGraw-Hill, $157.50, You also won’t be adding dead batteries and their packaging to landfills―and that’s a positive.