Thats it.

(slow learner - needs visual evidence) - the yuletide glasses don't help  .
Experience is the only genuine knowledge, but as time passes, I have forgotten more than I can remember
Volvo V70 P2 2006 2.4 Petrol 170bhp Estate SE
MG Midget Mk1 1962

Previous: L322 Range Rover TDV8 3.6 2008; L322 Range Rover TD6 3.0 2002; P38A Range Rover V8 1999

Be interesting to see if you have a current drain.

Pretty much what everyone else has already said, I recently connected an Ameter in series with my battery, straight after ignition is turned off I was getting 0.54 A which then went down to 0.074 after 20 mins or so. Obviously my car has no battery drain.

You need to resolve you parasitic drain issue rather than hope fitting your "battery brain" to resolve any issue. I can tell you 100% that a partially flat 11.8v battery will not have the balls to turn over a cold & frosty TD6 that's been standing, yesterday this was proven and not even a top of the range snap on jump pack and 2nd battery had the grunt. In the end it took a discovery 3, Jump leads and 30 mins to get enough power.

In a nutshell go methodically about checking your circuits, Ameter in series, bonnet shut, pull a few fuses & lock car... Drink tea/coffee and check 20 mins later. Repeat x 49 if needed and then work out the faulty equipment / wiring (whilst shaking like a dog on caffeine)