Solar Laptop Charger for Tour d'Afrique 2009
Something that readers of my TDA 2009 blog may not have realised, is that for the first half (2 months) of the tour, I was writing my blog posts on an Asus eeepc laptop powered almost entirely from a solar panel and li-po battery mounted on the rear rack of my mountain bike.
My home made charger worked perfectly, giving me an average one hour of netbook use per day and also allowed me to charge my mobile phone from a USB port on the netbook. Throughout most of Egypt, Sudan, Ethiopia and Kenya we had very limited access to electricity and on the occasions where mains was available, competition for "socket space" was fierce. There were also security concerns leaving valuable electronics lying around to charge up. Having independence from the grid was very handy and it was a fun and successful experiment :).
The photo shows the top of the unit which consists of a 12 volt and 6 volt solar panels wired in series to give a total of 18 volts and about 10 watts of power. The reason for having 2 panels is that it didn't occur to me until after I bought the first panel that you can't efficiently charge a 12 volt battery with a 12 volt power source.
The solar panels are screwed to a wooden frame which had space underneath for a lithium polymer universal external laptop battery to actually store the power. I wasn't about to subject my poor little laptop to the vibrations of crossing Africa on the back of a hard tail mountain bike.
In addition, there was a "mounting plate" made from 12mm marine ply which was bolted to the rear rack. In combination with the web straps this held the whole thing securely in place on the rack. It also protected the unit from dust and water (within reason) and meant that by unclipping the straps, the valuable parts of the unit could be removed and replaced in about 30 seconds.
The whole unit weighed 2.2Kg + the weight of the bike rack. It was heavy enough to upset the handling of my bike slightly and I guess it made a difference going up the many hills, although I can't say I noticed ( I was exhausted anyway).
Relatively speaking, my solar panel was quite low powered (size does matter!). It would take 5 days to charge from empty to fully charged, and this would give me about 5 hours of computer use. Combining this with charging both the laptop and my charger battery from the mains when power was convenient meant that I always had enough electricity.
Sadly, after the laughably serious hammering from the "roads" in Kenya, something in the external battery gave up the ghost and the unit stopped working (and started smoking!) at roughly the half-way point in Arusha. By this point, electrical sockets were much more common, and whilst it wasn't as convenient I was able to keep blogging by charging from mains power. I regret not removing the solar charger from my bike during the "Trans East Africa Highway" section, because then I think it would still be working today :(