It's not a jimny so I need help.

Lambert wrote:

Interesting. I have to trust that both the dealer and the independent auto electrician will have thought of testing the alternator and it's associated control units but I will ask the question directly

Well my Boxster eat batteries for 7 or 8 years before the alternator started to fail.  Clearly it was faulty all along. 

Re your maths, yes that is correct, over 100 days at 30mA and about a month at 140mA.  My Jimny draws about 40-50mA, quite a bit for a car with no alarm, most if not all must be the central locking.  50mA is a typical figure for a lot of cars, but if extra accessories, E.g. big stereo have been wired in they might be drawing current from the permanent live.

I also have a Ctek Battery Sense voltage monitor fitted, that way I can stand inside and check charge state.
www.ctek.com/uk/battery-chargers-12v-24v/ctx-battery-sense

Ctek say they are no longer made, but there are others.

Lets hope the garage finds something.

Robin

Also in your calculations you are assuming it drops to 30Ma immediately if you watch any of these diagnostic channels they leave the car for 30 to 60 minutes before it goes into deep sleep & is often over an amp up to that point, or drops gradually as each system closes down