Solar battery maintainers?

[TJ Hopland]

Anyone use or tried any of these products lately?   This is the type you use on a car that is parked outside and would usually lay on the dash and plug into the lighter.   I know on newer cars the lighter may not work with the key off and the windshield could have coatings that reduce the efficiency but I was curious in general if anyone has used them. 

I remember kinda looking into it many many years ago and they were pretty worthless and not that cheap but I know solar has come a heck of a long way in the last 20 years.    Seems like I have even seen them that are flexible and built into those shade things you can stick up to keep the sun out. 

[Big Fins]

For years, every VW that was built in the US, had a solar charger on it upon delivery. The reasoning was, the batteries wouldn't last 2 weeks from the parasitic draw of the onboard radio and computer memories. The 'new car get ready', guys usually put them aside and take them home. They were all over on FleaBay. I don't know about now because I rarely ever go there other than the value a product on the market.

A close friend of mine keeps them on his Cadillacs, boat and daily drivers when they need to sit for a prolonged period. He's never been let down by them. I'm sure it's not the fastest charge in town though.

[cadillacmike68]

Doesn't help if the car is garaged.

[bcroe]

Here at 42 deg Lat, winter days are very much cloudy, and short hours.  Those
factors will kill most of the potential output of any solar system (including mine,
300 feet long).  Long ago I tried one of those to plug into the lighter and lay on
the dash.  I found the average output (including the 20 hours it got no sun) was
not even enough to keep up with the clock.  I tried pulling the clock fuse, but the
lighter was on the same fuse. 

I went to plug in maintainers, some with really long AC cords.  They connect
through a permanently installed (polarized) EC3 model type connector, with a
small dedicated DC fusible link.  The EC3 is also useful for things like timing lights. 
Bruce Roe