Do the 2007 cars control their charging by varying the voltage the alternator creates?

On Friday after swapping the battery I noticed whilst messing around in the hidden menus that my 4.2 SC was only showing a static 12.5v. I plugged the IID tool in and monitored the voltage whilst driving and it seemed to be almost stationary at 13.2v.

I had a look again today and it was sitting at 13.5v but I’ve never seen it go any higher then that.

Can alternators get lazy or do they tend to pack in altogether?

Denso ones aren’t expensive at less then 200 quid but I don’t want to change it to find out that it’s not the alternator!

David. 2002 4.6 Vogue SE - Alveston Red with Lightstone Leather
2012 Range Rover 5.0 SC Autobiography in Indus Silver with Jet/Ivory Interior
2012 Range Rover 4.4 TDV8 Autobiography in Baltic Blue with Sand Interior

Seems a wee bit low David. When i first start mine, it sits around 12.x volts, then goes to 14.x volts after a few minutes.
When my alternator was failing, it was never above 12 volts.
One of the tell tale signs of an impending failure is a squealing noise.
Buying a replacement is the easy bit, changing it is more of a challenge  Got - 2017 SDV8 Autobiography in Loire Blue
Had- 2008 TDV8 Vogue SE in Java black
Had - 2007 S/C in Stornoway Grey

That’s what is kinda confusing me to be honest…

When I’ve had them fail in the past they’re just not charged much at all or in one case the volts have picked up when the car was revved but this one isn’t changing with revs.

It’s quiet as a mouse too. I replaced all the bearings on the aux belt last year so the front of the engine is quiet as a mouse so if it was noisy it’d be easy to hear.

David. 2002 4.6 Vogue SE - Alveston Red with Lightstone Leather
2012 Range Rover 5.0 SC Autobiography in Indus Silver with Jet/Ivory Interior
2012 Range Rover 4.4 TDV8 Autobiography in Baltic Blue with Sand Interior

Double check all earth connection between engine / body / battery, any poor connection here will drop a few volts giving the symptoms you have. If you have a multimeter, measure voltage between engine and battery negative with loads on and engine running, it should be 0v, you may find a small voltage indicating poor earth connections. BMW i3 Electric Car
2012 Full Fat RR 4.4 TDV8 (now gone)
2006 VW Touareg 3.0 TDi V6

Thanks

Will give it a check over.

David. 2002 4.6 Vogue SE - Alveston Red with Lightstone Leather
2012 Range Rover 5.0 SC Autobiography in Indus Silver with Jet/Ivory Interior
2012 Range Rover 4.4 TDV8 Autobiography in Baltic Blue with Sand Interior

I would think it is an earth too. But check the resistance in any cables as the wiring can go bad

Thanks guys. I agree with it likely to be an earth fault. I guess it's at an age where things break internally now.

Will hopefully get the covers off it tomorrow and get a better look at what's going on. Think I'll start by running an earth straight from the engine to the battery and if that cures it we know it's a bad earth rather then trying to find them all and clean them one by one.

David. 2002 4.6 Vogue SE - Alveston Red with Lightstone Leather
2012 Range Rover 5.0 SC Autobiography in Indus Silver with Jet/Ivory Interior
2012 Range Rover 4.4 TDV8 Autobiography in Baltic Blue with Sand Interior

I had similar on mine and changed the loom from the battery to starter to Alt and cleaned all the earths been fine ever since (about 80k miles ago )if it helps
To be honest I changed a load of cabling at 10 years as preventative maintenance prior to that changed everything on the front including alt

Did a bit of digging on this earlier and am not seeing an earth fault when checking with the meter or when running a cable from the engine to the battery.

Sandy, I did wonder about the positive cable that runs down to the starter and alternator. I’ll see if I can meter it out and have a look.

The car is starting and appears to be charging albeit not quite where I’d expect it to be so I might wait until it warms up a bit more before diving in!

David. 2002 4.6 Vogue SE - Alveston Red with Lightstone Leather
2012 Range Rover 5.0 SC Autobiography in Indus Silver with Jet/Ivory Interior
2012 Range Rover 4.4 TDV8 Autobiography in Baltic Blue with Sand Interior

Hi David,
I gave my SC a run this afternoon, after a week of sitting with no action, and ,via the GAP tool, it went to 14.7v then 14,5 for a while then settled after about 10 minutes to 13-12.7v constantly.
I put a new battery in 6 months ago and no probs.
My D3 runs a 13.5v currently when started and, the day before yesterday, I had to give her a booster pack to start.
That battery, I know, is on it's way out being 4 years old.
It could be just the battery???
Just at thought
Matt 2005 FFRR SC Java Black with Overfinch Exhaust (UK)
2008 D3 HSE Stornoway Grey (UK)
2008 D3 HSE Izmir Blue (ZA/Zimbabwe)
1995 D1 300 Tdi (Zimbabwe)

That’s a good point.

It’s a brand new battery so might not need charging much.

I’ll keep an eye on it and see how it goes. 2002 4.6 Vogue SE - Alveston Red with Lightstone Leather
2012 Range Rover 5.0 SC Autobiography in Indus Silver with Jet/Ivory Interior
2012 Range Rover 4.4 TDV8 Autobiography in Baltic Blue with Sand Interior