An emergency charger for phones available in the UK from Maplin for a discount price of £3.00 .
Comes with a bag to tie to the handlebars so you can recharge on the move.
I’ve tried it a couple of time but not in anger as a 705 has a 15 hour battery life.
I’ll post pictures when I can get around to it.
The charger uses DC/DC conversion to get blood out of a stone. This is the only way to get 5 volts from a 1.2 or 1.5 volt single cell. Under test it gave 5.4 volts from a 1.2 volt LI/Mh 2500 mA single cell. The unit gets warm and one cell should get you about half a charge of a Garmin Edge 705.
Recharging isn’t an instantaneous act, it takes time. This is why it has to be done on the bike. USB power is rated at 500 mA max @ 5 volts.
Plugging it all into your Edge with a decent battery in the Chamelion will result in the charge Icon lighting up on your Edge. It helps to shut your Edge down to help with the recharging otherwise you maybe powering only the backlight which is power hungry.
I’ve written other posts about USB chargers but this gives you the oportunity to buy something that works for the electrically challenged at a bargain price.
If you store it with a battery in it the LED in the other end can lead to the battery getting discharged accidentally. Two AA cells in the bag should see you OK.