L322 Battery/alternator issues - do these voltages look healthy?

Hi guys

I have a 2006 HSE (Jaguar 4.4 v8 engine). I occasionally get the odd HDC or DSC errors. Sometimes the car wont shift higher than gear 3. When these kinds of errors happen, I'll just pull over, turn it off, wait a few seconds then start it up again.

I've also noticed that sometimes the blower motor turns itself down (the speed), which I'm not worried/concerned about, just saying in case it rings a bell.

Whilst I was trying to park up today, the car shut itself off. I fired it up again and it shut itself off again. I turned off the AC blower and fired it up again, this time it was ok. Parked, did what I needed to do, came back to the car, and it started by fine. Tried not to run the AC blower on high after that as I didn't want to be stranded.

I took it to a garage who tested the battery and their tester said my battery only had 47 CCA and it needed to be replaced, although the tester settings only went up to 900 CCA, and mine is a 950 CCA AGM 105A Varta. They told me to go to their bigger branch so I went there and they tested it with a better tester (Midtronics MDX-651P AP) and it said the battery was at 12.1v with a measured 759 CCA. The machine says the battery is "GOOD, RECHARGE", with battery health showing around 30%. He measured the voltage with the car on and it was coming up as 13.2v.

I came home, a few hours later went out and popped the bonnet and without starting had around 12.15v across the terminals. A few seconds after starting I had around 12.89v across the terminals. I turned the blower fan all the way up and the headlights too. Got same, around 12.89v across the terminals. Then I turned on the high beam and fog lights as well. This time I got like 13.8v or so across the terminals. Measuring with a Draper digital multimeter with a good battery.

The battery currently on the car was fitted in May/June 2021. It was a brand new Varta 950 CCA 105AH AGM. I use the car around twice a week, usually for runs at least 15km (each direction).

I live in Qatar so car batteries usually last around 2 years here (as it's super hot here). Standard batteries usually last 2 years max. AGM ones usually last 2 years minimum, sometimes 3 years.

I'm thinking I might have an alternator problem. The shop I went to (reputable guys for batteries, tyres, etc, but not specialists) said that the voltage across terminals should be 14v minimum when the car is running. The Land Rover independent mechanic I spoke to here says that the voltage can be between 13.5v to 14v. Common knowledge says 14.4v is the target. There are plenty of happy people on these forums with 13.8v etc.

I'm not sure what the deal with my car is. Shortly after starting I got a reading of 12.8v. When I turned on everything I got 13.8v. The shop measured 13.2v. What's the deal here? Why so much fluctuation? If it was constantly 12.8 or 13.2 I'd say change the alternator, but the fact I saw it at 13.8 with everything turned on makes me hesitate. What are your thoughts?

It is difficult to get an accurately voltage measurement by just connecting a meter across the battery terminals, normally, the measurement you get is close enough but if you suspect either a slightly.dodgy battery or alternator the measurement can be misleading especially with a digital meter. I would never trust those battery testers the garage or battery supplier use, half the time they dont know how to use them properly. A healthy alternator should give a reading of over 14 volts with the engine running.

Col

I try leaving it on charge over night then check it

Colthebrummie said:

It is difficult to get an accurately voltage measurement by just connecting a meter across the battery terminals, normally, the measurement you get is close enough but if you suspect either a slightly.dodgy battery or alternator the measurement can be misleading especially with a digital meter. I would never trust those battery testers the garage or battery supplier use, half the time they dont know how to use them properly. A healthy alternator should give a reading of over 14 volts with the engine running.

Col

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So another person said this vehicle has a "managed charge system" and that my voltages look ok. Does that sound reasonable?

First off, AGM batteries may not be compatible with your car, they cannot just be stuck in any car so you need to check and don't just believe a battery supplier, check with a JLR dealer. With a normal Lead Calcium battery 12.15 volts is a very nearly flat battery and in that condition even with "managed charging" I would expect to see a minimum of 14.7 volts after starting. It needs to go on diagnostics.

Datatek said:

First off, AGM batteries may not be compatible with your car, they cannot just be stuck in any car so you need to check and don't just believe a battery supplier, check with a JLR dealer. With a normal Lead Calcium battery 12.15 volts is a very nearly flat battery and in that condition even with "managed charging" I would expect to see a minimum of 14.7 volts after starting. It needs to go on diagnostics.

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Agreed

Col

What everyone else has said.
Put a charger on it overnight then try again

IMO 60km a week is not enough to charge a battery.

Can't remember the exact values, but I have seen strange CCA measurements on a 2004 L322 when battery was still connected to the car. It appeared to be about 60% down from expected capacity. With the battery disconnected it was showing about 95% of the labelled CCA. I suspect it the resistance of whatever is connected with car switched off impacting the measurement.

backinblack said:

IMO 60km a week is not enough to charge a battery.

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It is.

backinblack said:

IMO 60km a week is not enough to charge a battery.

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It is on the new stuff with smart alternator control, they are specifically designed for the school run of 5Km a day

My first guess would be a loose or dirty earth / positive connection somewhere causing fluctuating readings / drop in efficiency of charge.

Scotiawhiskers said:

My first guess would be a loose or dirty earth / positive connection somewhere causing fluctuating readings / drop in efficiency of charge.

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As above ^^^ Check the earth link from engine to chassis. Test with a jump lead from battery negative to engine.

It's great getting half an hour & having a good read up.
Reading the voltages on batteries on Range Rover's can deceive you. It's the AMPs that are important, & many a time I've tested batteries & the voltages were in place as not to cause alarm.
A bad battery will give you spurious faults even though the voltages are in place. Buy a good quality battery listed for Range Rovers.
I have many batteries I've removed & stored in my workshop, perfect for normal vehicles but cause havoc on a Range Rover. I'm beginning to think they're a serviceable part.

Rick-the-Pick said:

It's great getting half an hour & having a good read up.
Reading the voltages on batteries on Range Rover's can deceive you. It's the AMPs that are important, & many a time I've tested batteries & the voltages were in place as not to cause alarm.
A bad battery will give you spurious faults even though the voltages are in place. Buy a good quality battery listed for Range Rovers.
I have many batteries I've removed & stored in my workshop, perfect for normal vehicles but cause havoc on a Range Rover. I'm beginning to think they're a serviceable part.

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Hi Rick, keeping well I hope?

Rick-the-Pick said:

It's great getting half an hour & having a good read up.
Reading the voltages on batteries on Range Rover's can deceive you. It's the AMPs that are important, & many a time I've tested batteries & the voltages were in place as not to cause alarm.
A bad battery will give you spurious faults even though the voltages are in place. Buy a good quality battery listed for Range Rovers.
I have many batteries I've removed & stored in my workshop, perfect for normal vehicles but cause havoc on a Range Rover. I'm beginning to think they're a serviceable part.

Click to expand...

Glad to see your still around.

Nice to hear you still about Rick hope your still as busy