A silly chem question?

[KennyR]

Nickel-Cadmium (Ni-Cd) has a very slight advantage over Nickel Metal Hydroxide (Ni-MH). NiCd last just that bit longer, are less heavy, cope better with heat conditions dicharging them, and last just that bit longer. But it's very close. Most people will never see a difference.

NiCd have a memory condition which means if you try to charge 'em when they're not fully flat, they don't charge very well. Intelligent chargers or intelligent users can get around this. But since most people have neither (:-P), NiMH is starting to replace NiCd.

And to answer your question - they have about the same lifetime, NiCd having a little more. NiMH will live better if you're an impulsive charger. NiCd will live better if you like to leave things alone, or if you live in a hot place (which you might).

[KennyR]

@gizz72

The batteries on the market today are probably the best you'll get for now. They don't last long. :/

There are other types of battery you could use - Lithium ion, for instance. Lithium holds more charge than NiCd/NiMH, but doesn't like high loads - best for very low power stuff, that needs to last ages. Mercuric oxide is even more like this. There's the old favourite, lead acid, too - but that's not really suitable for small things. And there will eventually be fuel cells - which will last hundreds of times longer than any battery. You might have to wait some years for those though..

Nice chart of battery types - here.

@cymric

Virtually all cadmium ends up in landfill. Sad but true.

And the NiCd vs NiMH argument is as old as the internet. :-D Real truth is probably one is neither better than the other taken as a whole, apart from Cd being toxic (not that Ni isn't, though...)