Mark: To keep the lights on and the camera going I have a multi-purpose battery charger. This contains around 24Wh of energy storage in eleven NiMh AA cells and circuitry to charge my laptop, satellite phone, mobile phone, camera battery and a PP3 for Ju’s Dog Dazer. It can also power a white LED tent light that sheds just about enough light to cook by. A cunning design means that some of the AA cells can be removed from the internal battery stack and exchanged with flat ones from a torch or whatever.
The battery stack can be charged from a DC supply of between 10 and 30V (which includes the laptop’s mains adapter) and from my Schmitt Dynohub and from a 5W solar panel. I seem to be able to generate about 8Wh from a day’s pedaling, which is supplemented by whatever the solar panel can gather.
It seems that from a typical day of pedaling and weak sunshine I can garner enough power to run the laptop for about an hour. I try to keep the laptop’s battery fully charged so that the power from the charger goes straight into doing something useful in the computer. It is of course possible to use it to charge the laptop’s internal battery but this is less efficient because it involves an extra two conversions between chemical and electrical energy.
Multi-purpose charger: [Link]