Electronic – How to charge a commercial lithium battery with solar cells

charginglithium ionsolar cell

I have a digital camera (Panasonic DMC-FT1) and will be going multi-day hiking with it soon. I'm looking to build a solar charger for it using something like this and strap it to my pack. Does anyone have any experience doing something like this, or any pitfalls in general that I may fall into (ie will my battery explode if I do xyz) ? There will be plenty of sun on my trip.

Battery markings:

  • Model: DMW-BCF10E
  • 3.6V 940mAh 3.4Wh Li-ion

Charger markings:

  • Model: DE-A60A
  • Input: 110-240V~50/60Hz 0.2A
  • Output: 4.2V 0.65A

Best Answer

You'd probably be better off taking a bigger spare battery.

But if you really want to charge using solar energy, you have to understand that there isn't much. If you have a 3cm^2 solar panel and go on the basis of 15% efficiency for the solar cell (which is pretty good), then plug that into the solar energy per square meter on Earth, which is from 1,413 to 1,321 W/m^2, which gives you about 59mW. Your battery is 3.4Wh, so it will take over 2 days to recharge it, nevermind that the sun is only around for a fraction of that or conversion efficiency.

Working backwards with those numbers, if one wants to charge a 3.4Wh cell within 4 hours, they would need a (3.4Wh)/(4h)/((1321W/m^2)*0.15)=43cm^2 solar cell.