Sunday, December 28, 2008

Solar battery charging

Everyone knows what happens to car batteries if the temperature is below freezing (0°C, 32°F). They don't give any power to the starter. From the scientific point of view their capacity drops a lot when it gets colder. For the driver it means one -- he can't start his engine and has to walk in the cold. It is especially difficult for diesel engines as they need to be warmed by glowplugs before they can be started and need a lot of torque in the starter (as they have high compression ratio).

Since I have my camping solar set, I wanted it to charge the battery that's used to start the engine.

My solar set consists of the solar photovoltaic panel, auxillary battery (under the passenger's seat) and a charge controller. This controller has three sets of connectors: source of power (to charge the battery), the battery and the devices to be powered from the battery. If the voltage in the battery is high enough, it allows the devices to use electricity. If not, the devices are disconnected.

I used the third set of connectors and attached a plug that's compatible with cigarette lighter sockets. If sun is shining, it charges the auxillary battery along with the standard one.

That's why when I leave my camper on the guarded parking near my apartment, I leave the solar panel under the windscreen. And why I chose a parking space with a lot of free sunlight.

From Volkswagen Transporter T3

No comments: