I have this wonderful little solar chargerhttp://www.bushnell.com/hunting/outdoor-technology/powersync/solarwrap-mini which is useful for battery back-up as it contains a 2200 Ma battery, and will recharge other tired batteries too. The trouble with such a device on the trail is that it is hard to deploy whilst walking, particularly if it rains a bit (electronics really hate water). You can attach it with a bit of string through the hole one end, and drill two holes through the end clips so that it can be attached at the other end. This will allow you to drape it down or over your backpack.
For a further modest investment you can place it and the item to be charged in one of Sea to Summit’s map cases which have enough attachment points to obviate this. I am going to make a PVC lid myself (using a waterproof zip which exactly fits my backpack (so it will stay in place) and which is easily removable when you want to get something out of your backpack.
The Bushnell Solarwrap Mini Dimensions: Weight: oz 3.1 oz, Size: in 4.3″ x 1.25″ Deployed Length: in 18.25″ Nonetheless it looks like it will fit in the Medium map case with the ‘tail’ folded over: http://www.seatosummit.com.au/products/outdoor/tpu-guide-map-cases/ (about A$30) You may find something else suitable on eBay cheaper but most do not have attachment points both ends.
| TPU Guide Map Case S | 212 x 302mm | 56g |
| TPU Guide Map Case M | 282 x 332mm | 78g |
| TPU Guide Map Case L | 332 x 430mm | 102g |
At 78 grams I feel this is a little too heavy for the purpose. It is also nearly twice as wide as it needs to be. If I make my own it will come down to more like 50 grams, I’m sure. A small price to pay though really for always having all batteries fully charged. Also I should be able to not carry at least an equivalent weight of unneeded batteries.
See Also:
http://www.theultralighthiker.com/mobile-phone-battery-life/
http://www.theultralighthiker.com/charging/
http://www.theultralighthiker.com/power-from-heat/
