So I'm thinking i need a solar panel to keep the main battery up to scratch ,
I've see a 4w one at maplins (sub £50) do you think it would be up to it ?
I'd plug it in to the mains and use a battery charger but its parked on the road

http://www.maplin.co.uk/Module.aspx?ModuleNo=115194
or this £80
http://www.maplin.co.uk/Module.aspx?ModuleNo=99760