Most of the time rechargeable batteries are the way to go, but there are some applications better served with disposable alkaline abtteries. When those batteries stop working it may mean they're completely dead, or they may have enough juice left to power low-draw devices like remote controls and wall clocks. Find out for sure with a battery tester.
Photo by Alexandre Vialle
When you're presented with several found batteries, you can always put them in a device to see if it will power on, but that won't give any idea how long that battery may last. Plus, if an appliance uses several batteries in a long strip it might draw more power from the two batteries on the outside than the ones on the inside; those inside batteries may have much more power left than the outside batteries connected to the terminals. Either way, a battery tester will come in handy, and you can pick up a serviceable tester pretty inexpensively.
When your alkalines won't power your cameras, game controllers and the like, try them in wall clocks, remote controls, spare LED flashlights and other low-draw devices before throwing them out. If you prefer to use only rechargeable batteries, low self-discharge NiMh batteries such as Sanyo Eneloops have a much lower self-discharge rate than normal NiMh rechargeable batteries and are suitable for long-term service in remotes, smoke detectors, and other low-draw devices.
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