I have a tdv8 4.4, yesterday it would not start, not even a click from the starter, put a jump pack on and it only managed a selonord click.
Had to go out so took wifes car and thought I would sort it out today.

this morning it had a completely flat battery and had to use key to get in car.

The nice man from the AA came and said battery was only 8 volts, it took a while to start the car from his pack and van, the instrument display was dead so disconnected battery which seemed to sort it.
Car started and we left it running for a while.

He tested the battery and that passed so battery okay tested for a current drain and after 5 min current drain was less than 0.5 amps.

Tested alternator voltage, at idle with current load (heated seats and lights on) voltage was 13.4, when engine revs lifted to 2000 went to 14.4.

He suggested I take it for a long drive so did, keeping revs up. Back home tested voltage again under load.
This time idle voltage is 14.4 under load and 14.4 at 2000 revs.


Now not sure if anything is wrong with alternator and battery looks okay. I now have car under charge and will see if voltage drops on battery overnight.

What should voltage be from the alternator under load, i understand the smart chargers do alter whats put in battery?
Are there any other tests I can do? I am reluctant to change out a good alternator and battery.

Thanks Roger. L322 4,4 TDV8
Freelander 2 sold
Honda Transalp
Sunbeam S7 deluxe (in bits)
Sunbeam S8 (restoring)

Forget charge rate for now, look at quiescent / parasitic current drain. anything more than 50mA (thats 0.05A) is a problem, and really anything consistently over 40mA should be investigated.

Looks like i need to buy a current clamp then, any recommendations?

Roger L322 4,4 TDV8
Freelander 2 sold
Honda Transalp
Sunbeam S7 deluxe (in bits)
Sunbeam S8 (restoring)

Yep, don't bother - the consumer ones are not great for low current as they tend to give false readings after an hour or more, if you have a multimeter with a proper Amps setting, use that, oh, make sure it has fresh batteries, a peak reading hold setting and a way to disable auto power-off.
Or if you want to splash a bit of money, the Hantek 365 datalogger is reliable and reasonably accurate according to a couple of people I know, the question is, is it better to buy something to find a fault you may never use again or pay someone else to do it for you?.

If you want to diagnose it yourself, ignore any measurements in the first 30 mins after locking the vehicle.

Don't forget some sponsor Glenrands up the A3 in Passfield if you need a great local independent specialist  2011 4.4 TDV8 Vogue SE Buckingham Blue with Ivory and clear glass = "Rory"
New Defender D300 90 on order so "Rory" will be going to a new home....!
1974 Series 3 Lightweight = "Millie"
My preferred specialist: www.glenrands.co.uk
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An update,

Charged car, then disconnected the battery and shorted positive and negative leads to reset everything.

Using my recently acquired current clamp shut down the car and watched current reduce in about 7 to 10 min to around 0.05 Amps.

Started car and checked charge voltage, this now sits around 14.7 whatever the revs or load.

Repeated shut down and checked current drain, seemed to take slightly longer but returned to around 0.05 amps. There seems to be a fluctuation on the clamp so repeated readings a number of times zeroing the clamp each time.

Went for drive and then tested again, similar results,

Voltage of battery is now 12.7. I will leave the car standing for a couple of days and check battery voltage again.

Not sure what else I can check any suggestion welcome.

I will check the site for known current drains just in case.

Roger L322 4,4 TDV8
Freelander 2 sold
Honda Transalp
Sunbeam S7 deluxe (in bits)
Sunbeam S8 (restoring)

What is the resolution of your current clamp? As I mentioned, 50mA is the upper limit, you need to look at peak and quiescent current draw over a number of hours - remembering that the EAS will 'wake up' to do a periodic level check & correction, it's not a quick job to do properly.

The unit claims 0.001 amps on the clamp but I doubt it can. I suspect its more like 0.01.

Rog L322 4,4 TDV8
Freelander 2 sold
Honda Transalp
Sunbeam S7 deluxe (in bits)
Sunbeam S8 (restoring)

A 10mA resolution isn't great when one digit out can put you under or over the 'there's a fault' threshold, my own clamp meters have a resolution of 1mA DC across different scales but TBH I still prefer to use direct measurement for anything lower than 500mA, mainly due to the amount of electrical noise that can be picked up and lead you down entirely the wrong rabbit hole....

If you do find there is excessive current draw, I'd recommend using a mV measurement across fuses to determine the circuit causing the issue rather than the traditional 'pull fuses until something changes' approach, you'll need to use some tables to work out what's going on - which I can't give you, but I did find one that looks reasonably accurate.

https://www.scribd.com/document/90080501/H...ross-Fuses

There's probably more in the public domain, that's just the first one I came across with numbers that look OK

Thanks for that, not sure how you measure the voltage drop as you would have to be in the car with it locked and internal motion alarm disabled. Also from memory the blade fuses stop you accessing the slots when they are fitted. it might be easier to pull the fuse and measure current across contacts with a meter. L322 4,4 TDV8
Freelander 2 sold
Honda Transalp
Sunbeam S7 deluxe (in bits)
Sunbeam S8 (restoring)

Push the door latches across so it thinks the doors are closed and use the key functionality to lock without interior protection, you measure the mV across the fuses with them in place to determine the volt drop across the fuse (by virtue of it's resistance) and use the tables to give an indication of current flow. Don't go pulling fuses as that will in most cases 'wake up' various modules and lead you down entirely the wrong path.

If you want / need to measure current across an individual fuse, I've used test adaptors similar to this quite successfully
https://www.amazon.co.uk/Gunson-77068-Auto...B002WMYBS6

Just circling back to the battery point.

Is it an AGM battery?

How old is it?

Knackered batteries can still present a good voltage, but rapidly deplete over a few days or 1 or 2 cranks. I see it a lot on boats. When testing a battery, I always test its voltage and cranking ability - if voltage has dipped below 12V and/or cranking ability is less than 70% of it's rated capacity, it's on its way out.

Once a battery has been allowed to go below around 11.5V, it's very very difficult to ever recover it properly again, even with the best smart charge tech designed to pulse charge.

It sounds like your alternator is functioning fine - the job of the diodes is to regulate the charge voltage to around 14.5V +/- 1V. Its the current which it increases with engine speed. 2015 Range Rover Autobiography 4.4 SDV8

Alternators have a common habit of discharging the battery so could be at fault so a replaement may solve both charging and discharging problems.

Alternator rectifier pack failure is not what i'd call 'common' - and would be certainly draw more than the 0.05A that is being measured. Alternator diodes only convert AC to DC, it's the regulator pack (commanded by the ECM) that controls the output voltage.
It's also stated that roadside had tested the battery (presumably with a Midtronics or similar tester) and it tested OK. AGM & Lead/Calcium batteries that have previously had a good state of charge maintained are perfectly recoverable from 6V and above so I wouldn't be concerned about any 'consequential damage' from it being discharged to ~8V.
There's obviously a transient electrical drain - which may well have been 'cured' by the battery disconnect / reconnect action, unless it re-occurs, then the pre-fault conditions need to be analysed and replicated exactly to be able to progress a diagnosis.

Morning update,

Yes its an AGM battery about 4 years old, the AA man did a battery test with his smart gadget which said all is okay with it.

Just taken battery voltage after standing for 18 hrs, still steady at 12.7, I will leave it another 24 hrs to see what happens.

Current draw still below 0.05 it seems to vary around 0.04 I took it a number of time after reseting unit and its consistent.

When I start the car tomorrow I will check the charge voltage again to see if anything has changed.

Its all a bit of a mystery

Roger L322 4,4 TDV8
Freelander 2 sold
Honda Transalp
Sunbeam S7 deluxe (in bits)
Sunbeam S8 (restoring)