I have been searching for a year on and off for the reason for my battery drain..Checked many things..as you would expect..
However while changing my roof hoses and rear seats were removed, I spied an elderly "Car Tracker".. I ignored it, and just chuckled..
6 months on, I mentioned to an engineer who designs this stuff and he said, oh "that old"....Argh..
It will be eating your battery, very old tech..
So yesterday, in the cool sunshine, out came the rear seats again.. and there it was nestled next to a large ECU (body processor?) behind the seat back..
A small plastic box 2 1/2 inches by 4 inches(remember those?)
Anyway, battery off( I fitted a switch, as fed up with flat batteries!), I then disconnected it..
Next I connected my trusty "Avo 8" on 10 amps current setting, in the battery feed.. locked the doors.. and now rather than stopping at 500ma after 20 minutes it was down to 25-30 milliamps --Hurrah! I had to change to the 1 amp setting to see the drain..
A real result.. So certainly well worth checking if you have an old one fitted, or certainly checking as you may not know it is there!!
Good luck all