Ok, slightly of topic, but since we are sharing the same problem, I guess I can count on some sympathy here :)
After reading the suggestion about mobile charger, and reading about the extra time it provides, I've started to look for a tekkeon device, and google did not help me much for finding it in London.
When I try to explain it to people in cell phone or computer shops, I get the "wtf?" look from everyone. In case someone knows where to visit london for asking about this gadget, I'd love to hear it
ps: I was in a conference today, and they gave us all begs with brochures and usual useless stuff. I checked it out and it turned out to be a mobile charger :) A quite crappy one though, not usable due to lack of cable etc..

Best Regards
Seref

For precisely what sort of mobile do you require a charger?

Try asking/looking/googling for a "USB charger" instead. Any generic one will do, you can use the cable that came with the reader. If I recall correctly from my time in London, Tottenham Court Road is an area with many electronic stores (a bit on the dodgy side sometimes...)

(Tekkeon is just one brand of many, the Garmin charger I use is nice because it plugs straight into the DR1000 and has all the international plugs, but all this can be found from different brands)

Are you looking for the Tekkeon MyPower GO, i.e

http://ecx.images-amazon.com/images/I/31cxesQQXjL._SS500_.jpg

Then you'll have better luck at electronic shops like Maplins

While they may not have the Tekkeon Product itself, you can easily find similar products. They are normally in the portable power section. Its also often called the emergency power section.

Maplins (http://www.maplin.co.uk/Search.aspx?menuno=84421) has a number of of them.

Argos (http://www.argos.co.uk/static/Product/partNumber/5466034/c_1/1|cat_10198997|Mobile+phone+accessories|10199053/Trail/searchtext%3EMOBILE+CHARGER.htm) has one as well.

And you can often find a really cheapo version in the Pound Shop's, which while basic, usually do work.

If you want the most options however, I suggest you stick to Amazon UK and search for Universal batterys / Emergency Battery's.

Oops, didn't get that you were looking for battery-based ("emergency") mobile charger. There are other brands: iGo, Syba, even Duracell offers a rechargeable charger pack. Looking at those I'd still go with the Tekkeon if possible (also available in black) but any of those will do the job, and you should find one or the other at some local electronics store.

I bought two in amazon.co.uk, 1 pound each+ 3 pound post cost. They works well.

Thanks for all the feedback. It appears amazon.co.uk will be the best choice for me too.
It is interesting, it is almost always easier to find and order stuff like this online.

Kind regards
Seref