Charging the batteries in the fields

I will leave in a few weeks for a three weeks trip to the Kalahari desert (desert covering parts of Namibia, South Africa, and a very large part of Botswana). As the trip will go to some very remote areas such as the Kgalagadi Transfrontier Park and especially to the Central Kalahari Game Reserve, there are no other possibilities for lodging apart from tents. Sleeping 10 nights in tents, I do had to find a solution on how to charge the K-7 batteries.

One solution would have been to charge the batteries using a universal charger on the car adapter. But, as the trip really goes to very remote areas where it is unlikely to meet a lot of other visitors, I do not want to put even more charge on the car's battery (a safari means stopping the motor at each sighting, and powerful lightspots connected to the car are used for night safaris).

After a lot of searching on alternatives, I nailed the choice down on the following equipment:

Flexible solar panel of 26W (http://www.thesolarpowerstore.com/solaris26.html)
Solarbooster, a small adapter between the solar panel and the powerbox (I had to ask for it when ordering the powerbox)
Powerbox SL-2000, external 50Wh battery with power regulator (http://www.offgridsystems...rt&Itemid=4〈=en)
Universal charger (http://www.ansmann.de/cms...igicharger-vario-pro.html)

I ordered everything and all arrived last week, allowing me to give it a first test run this weekend.

The weather on Saturday was quite grey, the solar panel was usually between 1-3W with peaks to 8W. The charge level indicator of the Powerbox did not move the whole day.

On Sunday, we had a pretty bright sunny winter day. The solar panel started to deliver in the early morning hours at 2W climbing pretty fast to 15W and reaching 20W at 11am and even 24W at midday. The charge level indicator of the Powerbox indicated a fully charged battery by midday.

The solar panel remained connected to the Powerbox during the afternoon. I connected an IPod to the USB output of the Powerbox, and the universal charger at the 12V output to charge a K-7 battery. Both ipod and K-7 batteries charged in normal time. Then, I set the output voltage to 19V and connected a netbook (without battery) to the Powerbox. I used the Netbook during a good hour. The solar panel was still connected during all that time, and the charge indicator of the Powerbox still showed 90% after that.

It looks like to be a working solution for charging batteries in the fields. I will not need to take too many K-7 batteries as I should be able to charge them in the desert. Now, it will have to prove in the conditions of the Kalahari desert...