Solar powered Palm

The Palm III

I hate batteries. They are expensive and pollute the environment. Rechargeables are a lot better. When I got my Palm III (thanks Onno!) I browsed the web to find information about my Palm. The amount is huge. I came across Peter's Pilot Pages, there, the usage of NiMh rechargeable batteries was explained. Also, a way of charging the batteries while the Palm was in his cradle. So I bought a set of NiMh rechargeables and a charger. While using one set, the other set stayed in the charger, swapping them every week.

While browsing on the internet, it became clear that the Palm does consume very little energy compared to the other PDA's (you know, the Windows ones). Could the consumption be so little that a Palm could live only on a solar panel, just like the calculators that have a solar cell (I love those)?

Then I came across the Green light Batteries site. There, solar powered batteries were offered. Should it be possible to mount a solar cell on the flip-top of my Palm III and never have to charge my batteries again? Am I the first who has done this? Yes! After an extensive search on the Internet I found nothing. That is, I did not find a PDA with a solar cell mounted on it. There do exist battery chargers using solar energy, but that's another thing.

So, on to version 1.0. I ordered a solar cell at Green Light and mounted it on my PDA Hmmm... not a success, the solar cell did only charge the battery when it was in full sunlight. Here in Holland we don't have a lot of that. Besides, when I work and use my Palm III I am in an office environment, with tungsten light as (energy) source.

On to version 2.0. It became clear that the solar cell should be as big as possible (The flip-top is 106 mm * 70 mm). I finally found the type SP6-100-12 from Plastecs Company. This company already offers the Pocket PAL for your pocket PC (the Windows thing!). That is a separate module, not a good thing, I want to mount the energy source on the device itself.

It seemed difficult to incorporate the solar cell onto the Palm. I finally found two thin, flexible solar cells at All Things Solar, the SP 4.2-37 type. Two of those fit nicely on the flip top of the Palm. These cells proved to deliver not enough energy also. I appeared that the efficiency of thin-film solar cells is much lower than the solid ones...

Back to the drawing board!
I now use the Plastecs cell, mentioned above.

Here the cell is mounted on top of the flip-top. The whole area is covered with solar cell. The maximum to achieve. In the left picture, the Palm is in the 'charging position', using a plastic coffee-spoon.

Yes it works, but...

Still, in an office environment, without direct sunlight, the cell does not charge. But when I put it in the sun, it is fully charged in a matter of hours. Thanks to a sunny spring here in Holland I never had to replace the batteries again! However, I want to charge the batteries using the tungsten light in my office, so the solution is still not satisfactory. Am I using the wrong cell? I don't know. If you have any idea why those solar powered calculators work using a very small cell, and mine doesn't, I'd like to hear from you.

Still I use the device with great pleasure, Using the Runtime application I can follow the state of my batteries

How to make your Palm solar powered?

What do you need?

I used the following schedule:


to be continued...