Wednesday, June 10, 2009

Preparing solar panels

As I mentioned here already, I plan to power all my camping electric needs with solar power. That's why I bought two 40 W solar panels with solar charge controller in february. Since we plan to spend three days living in camper during this weekend (starting on friday), I need to put everything together. Even if it all will be only temporary.

On monday I bought two gel batteries, 38 Ah capacity each. They look just like ordinary car batteries, only the connectors are different. Even the weight is similar -- those weigh 13 kg (29 lbs) each.

From Volkswagen Transporter T3
Today I spent about an hour soldering the cables together. The most important task was to solder the cable to the second solar battery (the first is already in the camper). I am not good at soldering, you can easily tell after a look at the photo below.

A bit about the cables I used here. The solar charge controller's manual recommends using a cable that has area of cross section of 4 mm2 (AWG 12), but I only had 2x0,75 mm2 cable for loudspeakers. So I used two pairs of this cable, removed the isolation from the ends and twisted the wires together. When I buy the proper cable, I'll connect it to the small parts of the cables I soldered now.

To the end of the cable from the solar panel I soldered a male connector used in RC toys and airsoft replicas. The connector is supposed to withstand the current of even 30 A, a lot more than I plan to put through it. 30 A with 12 V voltage is over 3 kW, and my solar panels give only 90 W (2x40 W and a small 10 W panel).

The female connector I soldered to the cable from the solar charge controller. I bought this cable yesterday, not the one I would like to have, but I had simply no choice. When I buy the proper cable, I'll simply replace it.

The same cable will be used to connect the charge controller to the batteries. I connected two pairs of wires to the controller as the batteries will be connected paralelly.

I left two things to do tomorrow in the camper:
  • solder the connectors to the cables attached to the solar panel I have in camper,
  • find a place for the batteries,
  • connect the controller with the batteries.
I wonder if the soldering iron will work with the 12/230 V AC/DC converter I have in the camper and the battery that's used there now.

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