I’ve just fitted a new Halfords Agm battery, I put it on charge and using the secret menus it’s showing 12.1 volts at rest my knackered old one I’ve just replaced was showing 12.3 at rest what’s everyone else’s battery voltage I’m sure it should be 12.6-9 2012 Range Rover Westminster 4.4 TDV8
2006 Discovery 3 HSE 260k miles and still going strong with a new owner

This is interesting, because mine is the same. Brand new top of the range battery, IID tool reads 12.1-12.3.

But I have no issues, so I am not too worried.

Only thing I can think of it that just opening the car turns on so many systems, that it drops it down by the time I read the volts?

Just took it back to Halfords they checked it and it was reading 12.3 after a 20min run asked to check one on the shelf it was showing 12.7, I told the car via the iid I had replaced the battery but it didn’t give me any options to choose the type I had fitted and on further investigation via the iid under type of battery it says unknown is this meant to be the case 2012 Range Rover Westminster 4.4 TDV8
2006 Discovery 3 HSE 260k miles and still going strong with a new owner

An agm battery should be charged at a low rate, imo about 36 hours and then it should read about 13V or so.
You really need a smart charger to do the job properly.
You can’t read the car voltage just after opening the car door, it could be anything down to about 12.1 to 12.2 Volts because of all the ecus switching on on door opening, never mind any inconsiderate battery drain.
If you must measure the voltage from within the car, leave it open for about half an hour and then expect a Voltage in the order of 12.3 to 12.6V if you are lucky.
The only reliable way to read the battery voltage on the car is to have a internal voltmeter that you can read through a window without opening the car. Easy enough to connect to the fuse board, either on a temporary or permanent basis.
I have a voltmeter permanently connected which l can read through the side window which l cannot deny is very reassuring at times.
These cars are seemingly never to be opened without being immediately driven.

Hi,

if you have a tow socket you can check the voltage via that as well

if I want to charge my car with a smart charger I use the tow socket for that as well

checked this morning via the tow socket 12.4v 2012 Range Rover Westminster 4.4 TDV8
2006 Discovery 3 HSE 260k miles and still going strong with a new owner

Can you tell an idiot (that’s me), how you check via the tow socket please?

ive got a comfort charger i use via the tow socket and can use a mulitmeter with this to check voltage, if you have the new 13 pin tow socket you can do it by just touching the correct pins this is also true of the 2 7 pin sockets the grey one for a caravan has a permanent live but if you only have a black 7 pin you cant check the voltage 2012 Range Rover Westminster 4.4 TDV8
2006 Discovery 3 HSE 260k miles and still going strong with a new owner

Furnitureman wrote:

checked this morning via the tow socket 12.4v