Warning light - cold morning

[rgc610]

Thanks for all the posts. Took some measurements this morning.

Engine off = 11.89V
Engine turning on = approx 10.5V
Engine on =14.7V
Engine off again = 11.9V

No warning light since but car roof still won’t go down using key fob and lights don’t come on when unlocking car with fob.

What do the above measurements show?

[flybobbie]

Go buy an AGM compatible charger and charge the battery. That way you can eliminate any battery problems.
If then everything works ok, you will then know it's a charging problem.
Always good anyway to own a charger.
Even with good voltages, batteries can do weird things. I've known them show 12volt, but still not crank a engine.

[rgc610]

Go buy an AGM compatible charger and charge the battery. That way you can eliminate any battery problems.
If then everything works ok, you will then know it's a charging problem.
Always good anyway to own a charger.
Even with good voltages, batteries can do weird things. I've known them show 12volt, but still not crank a engine.

Thanks for your response. If I just connected it to another battery for a while would that do the job? Would like to avoid spending more money if I can - new battery was £200

[flybobbie]

Go buy an AGM compatible charger and charge the battery. That way you can eliminate any battery problems.
If then everything works ok, you will then know it's a charging problem.
Always good anyway to own a charger.
Even with good voltages, batteries can do weird things. I've known them show 12volt, but still not crank a engine.

Thanks for your response. If I just connected it to another battery for a while would that do the job? Would like to avoid spending more money if I can - new battery was £200

Erm no, i wouldn't do that.
Do the job properly use a charger, as it will condition the battery properly by varying the charge.
Keep in mind you do not know how long a new battery might have been on the shelf.

[ph001]

Go buy an AGM compatible charger and charge the battery. That way you can eliminate any battery problems.
If then everything works ok, you will then know it's a charging problem.
Always good anyway to own a charger.
Even with good voltages, batteries can do weird things. I've known them show 12volt, but still not crank a engine.

Thanks for your response. If I just connected it to another battery for a while would that do the job? Would like to avoid spending more money if I can - new battery was £200

No, you need a voltage above 13.6V to start the charging process. Your battery volts in the morning seem a little low. If it’s below 12v it almost completely flat. Fully charged is about 12.6v in the morning.

[R.E92]

Go buy an AGM compatible charger and charge the battery. That way you can eliminate any battery problems.
If then everything works ok, you will then know it's a charging problem.
Always good anyway to own a charger.
Even with good voltages, batteries can do weird things. I've known them show 12volt, but still not crank a engine.

Thanks for your response. If I just connected it to another battery for a while would that do the job? Would like to avoid spending more money if I can - new battery was £200

No, you need a voltage above 13.6V to start the charging process. Your battery volts in the morning seem a little low. If it’s below 12v it almost completely flat. Fully charged is about 12.6v in the morning.

Not so sure about being flat if below 12V, mine only reads 11.6V in the morning. I've had it slip down to 11V and still been fine. It'll also sit for 2 weeks and start up after without any problems. He's already had a new battery fitted so I think the problem might be elsewhere.

I'd be suspicious about it being registered though. The chap at Halfords might not even know what battery registration is.

[ph001]

12.0V is about 13% charged....

battery discharge.png (82.34 KiB) Viewed 1323 times

[R.E92]

Yeh you're right, that chart puts my battery firmly in the replacement category

Maybe OPs new battery isn't getting charged properly because it hasn't been registered? I'd imagine the charging cycle would vary depending on age so it might still be charging it like a 10yr old battery.

[ph001]

Yeh you're right, that chart puts my battery firmly in the replacement category

Maybe OPs new battery isn't getting charged properly because it hasn't been registered? I'd imagine the charging cycle would vary depending on age so it might still be charging it like a 10yr old battery.

IBS measures the battery volts anyway though, so if it's low it will charge it. Parasitic drain is most likely cause.

[RobbiZ4]

[scootr]

I recently had a BMW X5 replaced under warranty because it was under their 12.6 minimum voltage in the AM. Mine read 12.34 and would not give consistent cold starts. 100% state of charge for a 12v wet cell battery is 12.73 volts and 1.277 specific gravity at 26.666ºc
Starting with 10v will cause the starter motor to draw excessive amperage (ohms law) the excess amperage is converted into armature heat. Resulting in reduced starter motor service life.

[rgc610]

Based on the responses I am best taking it to a garage and asking the question based on the information I have available? Nothing further I can do to diagnose it?

I’ve recently found out that when engine is off I can’t even open the roof when pressing the button in the car - get the amber roof sign light.

Thanks in advance.

[rgc610]

Hi guys,

Had MOT and Service and asked them to check why my roof won’t open with keys when engine off and they couldn’t work it out.

Interestingly, a fault code was on the car “A6a4 - Hardtop Operating Unit”. Any ideas as to what this could mean? They cleared it though.

[RobbiZ4]