Pretty much all batteries basically work the same way: Chemicals packed inside get freaky and produce electrons, which pool up on the negative end of the battery, essentially turning chemical energy into electrical energy—when you connect a battery to a gadget, the electrons run through the gadget and back to the positive end of the battery, completing the circuit and causing the chemical mojo that produces energy, making your toy robots go go go. The differences between various kinds of batteries come from the different chemical cocktails inside, which they're all named for—like your favorite actual cocktails, each one has its properties, making it good for some stuff and not others.
Silver oxide or silver-zinc batteries pack a good bit of power inside and last a loooong time, so they're the most common battery in watches and small toys—not to mention torpedoes and submarines, or other applications where performance matters more than cost. The downside is that the silver makes them expensive if they're bigger than the button size for gadgets. Oh, and the mercury leakage issue at the end of their life is kinda uncool.
Lead-acid batteries have two major types: a starting battery, like the one in your (gas-guzzling) car, which is designed for short power jolts, and a deep-cycle battery, which delivers a lower, more steady power level, so it's used on boats, campers, golf carts and backup power in various gadgets.
Rechargeable Alkaline: Surprisingly similar to regular 'ol alkies, they're slightly tweaked to take recharges—which means giving it some juice pumps electrons back into the battery. They don't self-discharge like the more popular nickel metal hydride batteries, but their capacity falls off with every recharge and doesn't quite match regular alkies. You don't really see these at Wal-Mart, if that tells you anything.
Nickel Cadmium, aka NiCads, some of the first decent rechargeable batteries, and still among the cheapest, so they were popular in toys and other gadgets. They recharge fairly quickly and will take a beating, but the memory effect (a recurring issue with rechargeables) is nasty with these—if you try to recharge it without using all the energy, large crystals build up that limit how much power it'll pump out next time to however much was used before you recharged it (like it "remembers"). Also, they'll leak out all their power after about 90 days, so you don't wanna leave them on your shelf or in a charger for a long time.
And that just about covers where we are now with portable gadget power. Feel free to wax philosophically on other battery banter in the comments, but we'll be covering what's around the corner in a future Giz Explains installment.
Something you still wanna know? Send any questions about touching, feeling or screening to [email protected], with "Giz Explains" in the subject line.
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