Battery problem

Just a bit more of the same - we have been having trouble with our AutoTrail Apache cab battery failing.  We purchased a new battery last year after two or three occasions when the old battery failed us.

Recently, we had reason to call out Green Flag to assist us and the helpful gent mentioned solar chargers which use the 'diagnostics socket'.  (I didn't even know there was such a thing, but it's well-concealed . . .)  If a solar charger was to be used, on the dashboard, then this option would avoid a connection via crocodile clips/cables through window, etc.  The cigar lighter appears not to be working in our MH.  

Also, we have now removed the control panel of our radio as, in the past, we believe this has been the culprit of the flat battery.

Have been having a look on-line and the AA one previously mentioned appears to have a different connection to the socket in our cab.  

Maplins have a number of solar panels, but can't identify one with a suitable connection.  Does anyone have any advice?  

Does anyone have any advice?

I didn't know such thing existed, but this appears to include what you want clicky though it's only 1.5w

A nice idea but you would need about 40 of them to provide enough power! Maybe there is a limit on the amount of charging current you can push through the diagnostic plug but in deep winter you probably need a 40 - 60 watt panel to keep the battery healthy, allowing for alarm etc.