http://www.autobarn.net/solarcharger2w.html

I am not sure if this will actually work but I think it will. Its not ment for you to charge a fully dead battery but rather, keep the juice constantly high when you leave your car for a period of time or during the winter.

With 2W, it is very little but better than nothing. We can hook it up directly to the battery rather than using the lighter outlet. However, my question is, is 2W enough to keep the battery working during the super cold winter?

So what do you guys think?

- Charles

Sorry.. Post in the wrong forum. How can I delete it

bump..

- Charles

Looking as some manufacturer ratings some some generic models from batterycountry.com, a 1W solar charger supplies 80mA @ 15V and a 2W supplies 135mA @ 15V.

Forgot what the rating is of the stock battery (IIRC somewhere around 30ish Ah - Optima Red starts at 44 Ah), but if you are planning on using this for an extended period of time it is not strong enough to keep your battery at full capacity - but it may keep it high enough to where you can still start the car. A rule of thumb that I use is 1% discharge per 24 hr period. Of course auxiliary electronics will have an impact.

The solar chargers used for volkswagons were only meant to keep the batteries full during transportation, and IIRC they are 1W models.