Winter Hack: How to Turn a Dead Battery into a Hand Warmer
My least favorite aspect of the winter season is how my fingers always turn into stiff, numb digits, unfeeling and seemingly incapable of making even the slightest movement. Yes, that might sound overdramatic, but if you hate wearing gloves like I do, you probably know exactly what I mean.
Stuffing your hands inside your pockets helps keep your hands away from the icy, freezing cold, but if you actually want to warm them up, consider dropping a dead battery or two in there with them. Seriously.
Instead of buying disposable hand warmers or making knitted hand warmers or microwaveable heat packs, all you need to help keep your hands warm are old, depleted batteries, according to Instructables user Jason Poel Smith. There is still a little juice left in them, so while there may not be enough to power your gadgets, there is enough left to produce heat.
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Grab any alkaline battery that's stopped working in your TV remote, your gaming controller, or any electronic device that takes batteries. Then, use a 1 ohm resistor (or a similar length of wire with 1 ohm of resistance) to create a bridge between the positive (+) and negative (-) terminals. (Others online suggest using aluminum foil instead of a wire or a resistor, but we like to play it safe.)
As the last remnants of energy are released through this wiring, a small amount of heat will be created, and you'll get a few minutes of warm, toasty hands. If you're out all day in the cold, you may want to use those disposable hand warmers after all, or make your own "hot ice" versions, but if you just need a few moments of warmth, this is a good way to get the most out of those expensive batteries you buy.
Of course, wiring two ends of a dead or dying battery together does require some safety precautions. Always make sure that the batteries you're using are alkaline, not lithium; lithium batteries have a tendency to explode when discharged, and are even more prone to do so when done quickly.
Only do this with batteries that are mostly dead. If you use a fresh battery, it will release much more heat and could burn up the resistor and burn your hand. For new batteries, you would need to use a 10 ohm resistor, according to Smith.