Got in my GV yesterday morning to run an errand and surprise surprise, my new battery didn't even have enough charge to light the instruments.
So today, with the ignition off, I checked the current draw of every fuse under the bonnet but only the IOD fuse was drawing any power. With interior lights switched off, radio switched off and doors closed, the IOD fuse was still drawing
between 0.87 and 0.88 amps.
So with the engine running I checked the voltage at the battery terminals, expecting to see 14 plus volts. I was only seeing 12 plus. Now suspecting the alternator is not charging, I disconnected the neg terminal on the battery but the engine kept on running. So I've removed the IOD fuse and I'll leave it unplugged for a few days to see what happens.

 

The low-amper-age IOD should not exceed twenty-five milliamperes (0.025 ampere) Al, yours is pulling up to three times the expected.

7 live items
Remote key fob
Radio
Heater blower
Folding mirrors
Central locks
Interior lights when the key is in the ignition

Most brand new batteries are less than 25% charged at delivery

Can I assume you did not switch off, lock doors and alarm on ?

Can I assume you did the metering with the bonnet open and the post not taped down ?

Can I assume you tested that before the 20 minutes 'sleep' function kicked in ?

Can I assume you did not do the buttonMOD ?

 

I charged the battery with mains charger.

Tests were done with ignition off, doors unlocked and alarm off.

Correct.

Tested after 15 minutes.

I haven't done the MOD yet. Still waiting for somebody to explain where the resistor goes.

So today I will be taping down the under bonnet alarm switch, doors locked and wait 20 minutes for it to go to sleep. I'll report back later.

 

I think you're on the right lines with the alternator charging voltage.

(BTW Don't run the car with the battery disconnected, spikes and surges esp if the Alternator and diode pack are dodgy could fry the ECU)

Even before doing buttonmod (Which btw the resistor goes on the connector. As you face the back of the car, under the battery housing, feel under with your hand and to the left nearest you corner you'll feel a connector. Wiggle it and drop it out, that's the connector that goes into the 'button'.
Even when the temperature sensor is at it's worst it should still give more than 12v at charge,

From my testing years ago, if you disconnect the battery temperature sensor, the system will default to full charge and give you around 14v, so maybe do that and see what you get, that will confirm if it's the temperature sensor (buttonmod) causing low charge, or if your alternator/diode pack is shot and need replacing.

PS, I finally found the previous conversation QinteQ and I had about voltages, IOD draw, etc. and to confirm what I found:
So it sounds like yours is never entering sleep mode.

So after waiting and testing you should see the IOD draw drop right down, it sounds like yours isn't so onto testing the list that QinteQ said. My first port of call would be the radio, seeing if it switches off, do your electric windows still work after power off, key out?
Also maybe pull the auto shutdown relay to see what current that drops you to (nearest to front bumper, left of IPM box).

It's a game of elimination, but we're getting closer!

 

Thanks Andy, I'll be going through QinteQ's suggestions this afternoon then work from there.

 

There's a buttonMOD walkthrough with pics on Andy's blog somewhere. Perhaps Andy can point you to where Al.

 

Thanks QinteQ,I'll have a look for it once I solve the current draw problem.

 

I have just looked for it for you but couldn't find it on either blog or tube M8. You might have to wait till he tells you where.

 

The story so far:
Tied down the underbonnet alarm switch with a cable tie.
Locked the car and waited 20 minutes. Current draw remained at 0.87.
Disconnected the radio-SatNav and current draw immediately dropped to 0.05 amps.
Disconnected the (faulty) DVD player and re-connected the radio. Current draw went back to 0.87.
So I've disconnected the radio again and I'll leave it unplugged for a few days to monitor the results.
I've also put a volt meter on the battery terminals, started the engine and revved it to 3000 rpm expecting to see the voltage rise to at least 13.5 volts but it remained at 12.5.
I'm wondering if my radio-SatNav draws more ignition off current than the standard radio's.

 

One+

Explains lots Al, and yes anecdotal evidence on the GV almost always points to the Radio as the first culprit for parasympathetic 'off draw'.