One by one, people will realize that NiMH never really lives up to
expectations. I have gone through a small fortune in cell phones,
digital cameras, and other doodads (OK, I'm a gadget hound) over the
last five years. Many developed useless NiMH batteries in only a few
months. Now I CAREFULLY check for Li-Ion when buying a new toy. I've
gotten years on my Li-Ion Notebook and camera without battery
replacement. There is a lot of BS circulating about NiMH (like any
other technical topic). From 1st hand experience:

1) NiMH does have memory effect (they may not call it that, but what
else can you call it when you are told to deep cycle a battery to
"fix" it?
2) NiMH self discharge is far worse than Li-Ion. I hate picking up
something that has been charged withing a few weeks and finding it
dead. If you have NiMH cells, get used to this.
3) Yes, Li-Ion cells are proprietary, but who cares if you can plug in
a camera and then use it for a few days. I've had one of those tiny
Casio camera for 6 months now and I can take pictures (on and off) for
2 weeks before it needs charging. Also some makers (I think Sony and
Konica) have cameras that use Li-Ion and AA Alkalines (of course you
could use AA NiMH if you like too)
4) NiMh performance may, on paper, be close to Li-ion, but in "real
world" electronic products, my experience is that NiMH is far behind.
Do not believe that you will get more charge-discharge cycles from
NiMH. Maybe in a contractor's cordless drill that normally gets run to
empty every time, But not in a camera, phone, or PDA, where it's very
normal to partially drain the battery, NiMH hates this, but Li-Ion is
very happy with this kind of use.
5) Notice that no decent notebook computer or cell phone uses NiMH any
more. These products now have brutal price pressure so the makers
would love to use cheaper batteries. They did use NiMH for a while,
but had to stop because the performance was just too crappy.

end of rant


LiIon also have the pseudo-advantage that the manufacturer *has* to
supply a decent charger for them. You can get equally good NiMH
chargers, but a lot of the NiMH chargers sold are junk. You have to do
a bit of research to get a good one.

Dave