In message , M. Joshi
writes

Hello all,

I'm thinking of connecting a 12V 10W solar panel permanently to my
vehicle battery as I am not using it very often.

The battery keeps going flat in the cold weather.

What I wanted to know is if others have done this and whether there is a
danger of damage leaving the panel connected when starting the car?

The panel I am thinking of purchasing off eBay has a protection diode
built-in.




The diode is to prevent the battery discharging back through the solar
panel when output falls below 12v

I had one similar from Maplins for the caravan - complete waste of time.
Gave 17v in bright sunlight but dropped to about 7v in any shade.
Failed to keep the battery charged with only the alarm to cope with.
--
hugh