Solar panel to keep car battery charged

[Gab250]

Hey, I use a car battery for alot of electronic experiments, mainly testing bits for cars, and I'd like a solar panel that I could plug into it to keep the battery up, instead of having to plug it into the mains charger often, what can I use? also, are there any I could get that would give a reasonably fast charge on a sunny day, enough to make a car start in say, a couple of hours?

Gab

[anyone]

saw some yesterday, panels going for around $300-$400, a regulator to keep the dc at 13.8v $100-$150, some wire to hook it up

[Learjet]

What's a fast charge? 12V solar panels will put out about 1 amp for every 20 watts in full Sun roughly.

Regulators are cheap if you get them from China. $25 gets you a 10 amp regulator. Edit, I see they are available for as low as $15 now including freight. I've been ripped off lol.

Solar panels, not so cheap. 50 watts about $160 - $200 and 100 watts about double that.

I just had the darkest day here in Mackay. At midday, 250 watts of solar panels were putting out only a few milliamps. Don't throw away the mains charger!