No, more drain!! Once the dash was off I noticed the carplay was staying on despite being on a ACC triggered relay module. I have taken the relay off and now ACC is connected to one of the cig fuses with a piggyback blade fuse. This is ignition switched and works, I have tested it for a couple of days now.

In summery:

- Check carplay installation, my harness was faulty.
- I have also taken the cd out and put an optical loop, considering doing the same for DVD

pd SOLD | Tuned MY 2011.5 Range Rover Autobiography 4.4 TDV8 Orkney Grey | e-diff | ACC

New Toy: Unimog U1550L/37
New : G350D

Great news! Glad you found the issue!

I've still not had any problems recently but I'll add this to my list of things to do on the car

After almost a year of no issues, I had a flat battery last week!

It's bizarrely about the exact time of year I started having the issues in the first place, which is niggling and makes me think it's somehow related to the temperature (the problem stopped once the weather got warmer last year).

It's at the garage this week for new tyres and a gearbox flush, but once it's back I'm going to strip the dash and change the powering of the CarPlay box so it's disabled once the ignition is off, hoping that'll cure it once and for all!

If the issue is ambient temperature related I'b be inclined to suspect the Fuel Burning Heater.

Yeah, possibly. The drain is happening when the car's locked and turned off (ie: the FBH isn't starting up), but maybe it's waking up and doing something - I've not heard any noises from it tbh.

On a similar vein, there could also be something like heated door locks or wing mirror glass heaters being woke up when the temp's below a certain value.

When I went through the whole pulling fuses and testing current draw routine, I could never find an obvious fuse responsible, just the current from the BCU itself (obviously, not much I can do to pull the fuse governing the BCU!).