Hello All,

I have doen a search and found a plethora of infomration all good.
Used the battery change tutorial when changing the battery yesterday , very useful it is too thanks @scuddriver
https://www.fullfatrr.com/forum/topic43662...ery+change

So before I changed the battery, keep in mind the FF started every time. ( approx once a week) But had only done 1500 Miles in the last 7 months. I checked the battery % and it was showing : One reason I checked this was to see if it was affecting the FBH operation, Still to be checked.

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Oddly, I was also doing very similar today on my own 2011 TDV8 whilst trying to work out my flat-battery issues

I started with a 95% charged battery (according to the same live values you used), the battery had been on charge overnight with a CTek, so should have really been fully charged (the CTek seemed to think so).

For the first 20 mins of driving, the battery voltage fluctuated from 14.6 (mostly when going down hill in gear and off the brakes) down to about 12.1volts.

I didn't think to record the session, so I'm working from what I saw when looking at the screen every few seconds rather than giving definitive numbers - so please bear that in mind!

After about 20 minutes of driving, stop start traffic, around the town with a couple of brief A-road sections, the voltage stabilised at about 14.7v (AGM battery, ~11 degrees celcius outside temp).

I'd had the heater on, heated seat, headlights, blower on low, sat nav on but nothing else and I was seeing loads between 20 and 60amp whilst driving (again, going off the GAP's live value metrics).

All this time the GAP was saying battery capacity was dropping from 96% down to about 92%, once the load eased off to about 20amps and the voltage went back up to 14.7v the charge started to go back up. I think I ended the drive on about 94%.

I didn't check the voltage without load, because right now I have a constant 2amp draw from something - which is what I'm trying to diagnose. I'd have needed to disconnect the battery to get a true reading of the unloaded battery voltage.

Things I can say from looking at other posts on this subject;

The TDV8 4.4 probably doesn't let the alternator kick in to begin with, it lets the battery take the load for the first few miles of driving as the battery can take it and to pull that much current from the alternator would hit fuel consumption. Apparently this is a method of saving fuel, it waits till everythings got warm until it kicks the alternator in and starts to recharge the battery. What I read suggested this only takes 2 minutes, though, it was more like about 20 from what I observed.

Second thing I read was that the alternator voltage is dependant on external temperature, obviously the AGM batteries can take a higher voltage too, so 14.7v that I saw is possibly dependant on the external temperature - your mileage may vary!

I'm still trying to get to the bottom of my issues and have the battery disconnected right now so I can put a fuse buddy onto the entertainment system fuse and start to look for where the problem is (I know the dash backlight and the backlight on the hazard warning triangle never go off when the car's locked, so it's something to do with that - just don't know what that means yet).

Anyway, hope this helps - I'll probably go out for another drive tomorrow and do the same thing, I'll need to record it this time so I can be a bit more imperical though

Good detailed info here gents, thanks for documenting as I'm sure it'll be useful to plenty of people in the future. Watching along to find out the root cause of your battery drain, as 2 amps is pretty big  2011 Vogue SE Tdv8 FFRR

It is indeed, I've seen it drop to 1amp which I think is generally where it's at, but it can flatten the battery overnight so it's something major. The instrument cluster screen suggests it's BCM I think, which would account for a large amount of drain.

I did spot an error code about the drivers side door lock switch being low, which I'm wondering is causing the BCM to stay awake but, I dunno, more investigation tomorrow!

*EDIT* Aparently I did record some of the run: https://www.dropbox.com/s/fsavc75o7y0zh0k/run1_Log.pdf?dl=0

I really don't know how to interpret that - it's the last 5 or 10 mins of the run and shows the voltage is all over the place, though it stabilises out towards the end and starts to charge the battery.

I was basically driving for 2 lots of 45 minutes.

Will be interesting to see what you find.

Cheers

Well the good news is, the FBH is now working.

So that makes changing the battery worthwhile.

Cheers