I was always stumped about what to do with partially depleted, 9-volt smoke detector batteries. They’re usually drained enough to cause the smoke alarm to chirp (typically at 2 a.m.), but they still have some juice left, so I hate to just recycle them. I looked around for another device to use the batteries in, such as a transistor radio, but few items use 9-volt batteries anymore.
Recently, however, I found a little LED Blocklite flashlight that does use a 9-volt battery. For about $5, you can turn your old battery into a compact — and surprisingly bright — flashlight. Now my little light goes with me on evening walks, and it lives on my nightstand. I plan to get several more!