present battery technology

Voltage would be a problem.

They are possible but will probably not be available to regular consumers. Rechargeable lithium batteries can be quite hazardous. Newer technologies, such as LiFePO4 cells are not nearly has dangerous though. The average consumer is not ready to handle swappable lithium cells. Imagine someone plugging a lithium AA cell into a regular charger or plugging a AA NiMH cell into a lithium charger, that could get bad. Lithium cells have the best weight to power ratio going but it would be too expensive and too much liability to cram that into AA cells, they would have to have charge control devices built into each cell for regular people to use. Even the AA lithium batteries by Energizer can vent harmful gasses while being used (not much but enough that they should not be used in air tight devices).

Like Eugene said, one of the benefits of Lith-ion batteries is that they can output a higher voltage than that of NiMH, so they wouldn't play nice with your camera. You could find lithium AA batteries at any rc hobby shop, and buy a charger for them, but they would output better than 3 volts per cell. That is more than double a standard AA.

And they blow up if you overcharge them.

http://www.batteryjunction.com/li14reaasi38.html

When the question came up in another forum some silly sod had to argue with me that because you can fit those 3v/3.8v AA sized batteries into a camera the answer is yes they do exist.
However my point was and still is that is like insisting you can put petrol inside the tank of a car that takes diesel..
(the guy never got the point,)
Yes, so the above info is correct. Cameras and devices that take standard AA batteries can only handle up to 1.5v (Alkaline) and more commonly now up to 1.7V (disposable/one use Lithiums)
Li Ion is typically rated at 3.8v so far too high for the circuits to handle it.
Some cameras (Ricoh for example) can in fact take AAA (1.5v) and proprietary 3.8v batteries but they use different contacts with their own power circuit, effectively they have a built in transformer)
Franco

OK, so here's a crazy thought: If a device uses 2 AAs in series and is rated for 1.7V cells, you could use one 3.0 – 3.8 V cell and a dummy cell that passes the current through. Voltage would be approximately the rated level. NOTE: I have not tried this, am not recommending it, and will not be liable for anything that happens if anyone else does it. Just sayin'.

Hmmmm… Franco, that dual contact point setup is fairly "foolproof" but some fools may still screw it up.

I do understand the dangers of charging (over charging) lithium rechargables.

I guess my real question is "If new laptops can have rechargable lithium/polymer batteries could the same technology be used in backpacking electronics?"

Maybe the answer is "Yes, if the devices are SPECIFICALLY made for those type of batteries."

A problem with making AA 3V Li Ion more readily available is that inevitably people will put them into gear that cannot handle them.
This is why Li Ion for cameras have a totally different form factor. Mind you that is also convenient when you design a camera because you can then find a battery that fits the spare space…
Franco

What I'd like to see is some kind of contraption that will allow my AA / AAA battery chargers to charge CR123 batteries.

I guess my real question is "If new laptops can have rechargable lithium/polymer batteries could the same technology be used in backpacking electronics?"

Yes. As you said, they have to be designed for the higher voltage. Having a different battery casing is a good way to prevent mistakes.

As for gear that already uses lithium rechargeable batteries, check out the Spark ST6 headlamps. They use the same type if cells you might find in a laptop.

50 grams without the battery, 150 grams with the battery. This one gets 360 lumens for 1.8 hours on the brightest setting, or 12 lumens for 6 days on the lowest setting.

"What I'd like to see is some kind of contraption that will allow my AA / AAA battery chargers to charge CR123 batteries."

You need special Lithium battery charger to avoid fire producing event : )

"What I'd like to see is some kind of contraption that will allow my AA / AAA battery chargers to charge CR123 batteries."

You need special Lithium battery charger to avoid fire producing event : )

OK, how about a special compact and light weight lithium charger that will charge AA / AAA / CR 123 batteries?

They don't have rechargeable lithium AA or AAA batteries?

"What I'd like to see is some kind of contraption that will allow my AA / AAA battery chargers to charge CR123 batteries."

You can kinda, sorta do it, with a purpose-built charger and RCR123 cells. And Steripen sells a version of their Adventure Opti with two RCR123s and a solar charger/storage box. Since the Meridian Design mUV charges its internal RCR123 directly from any 1.5V battery, it shouldn't be difficult to replicate the mUV circuitry as a tiny, standalone module but I'm not sure what would be gained as a result (considering one would have to carry main batteries and charging batteries).

I'll add Li-ion cells aren't "magical" in terms of how much power they store (measured in mAH) but their base voltage, light weight and low-temperature performance do make them attractive. NiMH cells are easier and safer in about all aspects, but are heavier and put out lower voltage.

Cheers,

Rick

I looked at a couple batteries I have

123 lithium rechargeable – 900 mAh, 3 V, 16 g – 169 mAhV/g

AA NiMh – 2500 mAh, 1.2 V, 29 g – 103 mAhV/g

Not that much advantage to using Lithium

But, in the future they may make better Lithiums?

The only good thing I've heard about CR123's is that you can buy them at the grocery. For rechargeable lithium, the go to battery type is the 18650. I believe the 18650 is 1.6 ounces.

18650 – 2600 mAh, 3.7 V, 1.6 oz – 211 mAhV/g

yeah, better than 123, twice as good as NiMh

"18650 – 2600 mAh, 3.7 V, 1.6 oz – 211 mAhV/g"

The point remains the same. Yes they do exist BUT NOT for cameras and gadget that take standard AA/AAA …
(that is , once again , about voltage not fit)
Franco

What about this? I realise its not lithium but they get really good reviews…

http://store.apple.com/us/product/MC500LL/A?fnode=MTY1NDEwMQ&mco=MTg1ODIwNDg

I've not bee happy with the apple batteries, mine don't hold a charge.