Last month we rigged up our solar panel to charge a car battery. The battery is for running lights and radio in our new Garden House, and also for the backhoe.
Here is a graph for about 2 weeks of the 10W solar panel charging the battery. There is an impressive increase in voltage on the battery day-to-day... especially on those sunny days. Even the cloudy and rainy days we had showed noticable increase in charge.
There were a few days we used the battery for lights, and also for the backhoe work we've been doing. Other than those dips, you can see the steady charging of the battery. Its working great!