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[05omegav6]

Alternator working as it should.
Battery charging as it should.

Plod wiring pulling 0.15A, drops to 0 with ground disconnected. Totally isolated from rest of car.

Feed to main fuse box at battery draws 0.75A upon ignition switch off, dropping to 0.55A after 5 minutes, then finally settling at 0.4A.

Pulling fuses FV5 and FV6 kills this draw dead.

Pulling all the cabin fuses one by one makes absolutely no difference. Likewise the accessible relays next door.

There is a 12v socket connected to the switched live behind the cabin fuses, but this is discounted as it is downstream of the relevant fuse.

The only unfused feeds from FV5 go to the Immobiliser and Alarm. Alarm irrelevant as plod never had one.

The only unfused feeds from FV6 go to the Indicators, the Headlight Switch, Heated Rear Window and Autobox. Autobox irrelevant as car is manual.

Is it feasible that this current drain is down to the light switch

[Broomies Mate]

Might sound obvious, but remove the light switch and see what happens? 

[tidla]

Does the heated window have a relay? (im guessing so)

[zirk]

If its plod, pull the fuse, if it goes through one, for the boot release, may have instant open relay fitted, which sticks, had something simular before on this.

Is it 3.0 or 3.2, if 3.0 relay is behind headlight switch, as it became a standard Plod Mod, if 3.2 could be anywhere but most where in relay box in Engine Bay.

[05omegav6]

3.2 but estate, not saloon

[zirk]

3.2 but estate, not saloon

Wont be that then. 

[05omegav6]

Battery struggled to start the car half an hour after recovery this morning. Turned over but failed to fire, putting the immobiliser light on. Second go saw it start.

Currently tempted to chop it up where it sits

[Entwood]

Battery struggled to start the car half an hour after recovery this morning. Turned over but failed to fire, putting the immobiliser light on. Second go saw it start.

Currently tempted to chop it up where it sits

Can I have first dibs on ABS/TC bits .....    as well as air con compressor ... 

I know .. fruitless request .. you'll mend it soon enough ..

[2nddaniel]

Feed to main fuse box at battery draws 0.75A upon ignition switch off, dropping to 0.55A after 5 minutes, then finally settling at 0.4A.
Battery struggled to start the car half an hour after recovery this morning. Turned over but failed to fire, putting the immobiliser light on. Second go saw it start.

I had the same trouble, ended up measuring load, and eventually decided the altenator was faulty, that it wasn't charging.
I was wrong.
I had the alty tested, and was told it was very healthy.
It's an intelligent altenator (like on a BMW) only charging the battery when required.
I replaced my battery and all my troubles were gone. I got the biggest bastard that would fit, 75Ah with 700 cold cranking amps.

If you aren't convinced that your battery is faulty (i am though), consider the following calculation:
Assuming a 60AH (60 amps for an hour) battery with a 0.35amp drain (my measurements);
60/0.35= 150.
That's 150 hours, the battery should run that piddling little load for over 6 days.

Itls only surface charging mate. The altenator is seeing a healthy voltage at the battery terminals and stopping charging, the battery is just weak.

My old battery was only 4 years old.

These hi spec omegas have a lot of kit that runs on after the engine switches off. I found 3 fans under the bonnet, - that coupled with alarm current, interior light timers, immobiliser timers, and that sort of thing was killing my old battery within 10 mins after a long journey. I was expecting the battery to be getting a right old boiling, but it weren't, just a surface charge - cos it was knackered.

You can prove the battery is bad yourself, like this:
Charge it for a few days, maybe over the weekend, On Monday it'll seem like a new car, by the end of the week it'll be struggling to start.

A bit of a long spiel, i know. I hope it's useful though.

[05omegav6]

That makes sense

Need a new battery for tother one anyways so I can get one for both cars. Will the TD battery fit?

[Nick W]

You should  consider buying a battery tester. A tool you won't use much(unlike mine), but is handy to have. Cheap too.

[2nddaniel]

TD ? Turbo Diesel?
I don't know if it will fit.
I took my old battery off, noted that it filled the battery tray, took it to Digby and Sons in Heywood (who, by the way, bench tested my altenator for free -AND told the truth - not pretending it was faulty and charging for a new one), and asked for the biggest capacity battery they could source that was the same physical size as that old one.
And they did.
£90 plus vat.
Fitted. (the following day).
 

[05omegav6]

You should  consider buying a battery tester. A tool you won't use much(unlike mine), but is handy to have. Cheap too.

AA battery tester initially said 'Recharge then retest' followed by 'Charge fully' on the second test, suggesting it simply needed a decent charge.

My charger quickly changes from Charging to Charged when connected, implying that it charges in the same manner as the alternator...

Alternator looks to behaving as expected according to Kevins guide, which further points to a dead battery.

[Bigron]

The battery has gon low capacity, hence the short time to apparent full charge - is it sulphated up? Not much you can do about it if it is, but when the plates are coated with lead sulphate due to abuse or old age, you aren't using much of their active area.
A quick check would be to charge it fully - to gas point if you can see the electrolyte - and then use a known current load (headlamp bulb, 60watt, approx 5 amps) and time it to extinction.
With a healthy, full capacity battery your bulb should stay lit for at least 10 hours. Any less and it has proportionately less effective capacity.

Ron.

[Kevin Wood]

Notwithstanding the condition of the battery, if you still have a 400mA load when off, the battery will go flat in short order.