Hello Brendan,
I have the same problem,no garage and go away with work for 2/3 weeks,i have just put on Saturday a new 95amp battery so i thought i would go down the solar panel route,I went Maplins to get one the guy asked what is the drain ampage ? because pointless to get 1.5 amp charger if its losing 2amps, so he said check with Lexus, so this afternoon did just that but the service guy and 2 techs didn't know. So the big question is do you or anyone on here know the answer ???
Regards,
Alan