I've found a few times that I've run out of juice for some of the gadgets in my bag at a time when I really needed them - and had no charger or even a poweroutlet nearby.

Anyone have any experience using low-cost solutions like these (for N810):

(And yes, I'm also looking at getting, and bringing a spare battery).

http://www.brookstone.com/igo-powerx...st1FDT|7209217

http://www.brookstone.com/Quick-Char...st1FDT|7912705

The typical response when asked this sort of question is the tekkeon tekcharge 1550 (available from Amazon) using Sanyo Eneloop AA batteries

Thanks, about the same price as well - and a recharger.
Nice

...and the Canadian equivalent is the Noma RX-4, sold at Canadian Tire for $25.

Sanyo also makes an Eneloop-based pack that charges from an AC plug or a miniUSB port (laptop etc.), and will feed two devices through standard USB ports.
It's not really low-cost, but compact, classy and very efficient - well worth it IMHO.

@fpp

Interesting I didn't know that. I'm a huge fan of eneloop batteries so I'll have to check that out.

They come in two capacities. Mine is the middle one on this page :
http://www.eneloop.info/products/mob...-versions.html

Nokia also makes a portable power source but I'm not sure on the capacity.

http://www.portablepowersupplies.co....ource=googleuk

If you like the ability to use AA primaries in a pinch, the Tekkeon devices mentioned are apparently good. But I prefer DX sku.18883, using Li-ion 18650s. These batteries, while somewhat larger, offer much better energy density -- they're the cells used in almost all laptop batteries, so that's where most of the battery tech advances are focused. While volume isn't necessarily a perfect metric of pocket space, a good 18650 has 7% more volume than 2 LSD AAs, but 2x the energy storage! (The one bundled with sku.18883 is probably only 2.2Ah or so, but that's still over 1.6x the energy of 2 AAs.)

The only real disadvantage is the near-impossibility of using it with primary cells -- 3xAA or 3xAAA in series would drive the electronics, but most people are unlikely to have the magnets and wires in their pockets to jury-rig such a fix. (I often do, but probably wouldn't if I ever needed it. ) A 3V lithium primary (such as CR123A) with an appropriate spacer might work after a fashion, but you could only use the first bit of power before it would detect low voltage and quit.

A personal bonus for me, as a flashlight geek, is that many of my flashlights also use 18650 (or 14670, essentially same length, but same diameter as AA; these also fit in sku.18883), so one collection of spares can reload either, and this can serve as an emergency 18650 charger. Also, the USB flashlight head, while not spectacular, is enough to impress your average flashmuggle, and certainly usable, especially with a USB extension cable.