http://www.cleverscampcamp.com/camping-flashlights-head/

UK Electric Battery Query?
I recently bought a similar light to this from ebay http://cgi.ebay.co.uk/56-LED-Head-Lamp-HeadLamp-Torch-Camping-FlashLight-o6_W0QQitemZ200173349055QQihZ010QQcategoryZ106984QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
which i use on my helmet to ride off road between pubs in the dark with my mates. Its quite bright but it seriously eats batteries. It uses 3x AAA type and i recently bought duracell batteries for it and on its maximum brighness it lasted about 2 1/2 hours.
I take a rucksack and im thinking about wiring up some larger batteries that would last longer. Rechargeable batteries dont seem to last long so i thought that if i got some bigger batteries eg ‘C’ Type and kept them in my rucksack with a wire running to the light it might solve the problem……but lifes never that easy, is it?
I was hoping that someone with some electrical knowledge could advise me on a CHEAP ( i’m currently dead skint!) way of powering this light for about 2 hours at a time.
Many thanks
Following along the lines of your suggestion, I would buy a plastic 3 AA battery holder that connects the 3 batts in series.
You might want to test the existing unit with a voltmeter to make double sure I am correct that it does run off 4.5 V and not 1.5 V. I.e. batts in series.
The holders can be ordered at
www.digikey.com or www.mouser.com.
Then solder the long wire pair between the holder and the LED device. Make sure you get the polarity correct. If the device has solid state electronics inside, the wrong polarity could kill it.
Standard good grade AA alkaline batts will last much much longer than the AAA batts. My guess is maybe 5X to 8X longer.
Surefire Saint – LED Head Lamp