Total loss of external lights whilst driving in the dark! - 12 volt battery failure indicator

[Ezza]

Anyone lost lights whilst driving? I was driving in the dark (thankfully on a lit stretch of road) when my headlights & I think other external lights went out, & stayed out. I'm not sure what the dashboard indications were at the time (I had bigger things to think about - like seeing where I was going!) Pulling & holding the main beam stick towards me gave me lights again (until I could pull off the road safely & wait for daylight!) When parked up, I noticed the red fault symbol for the 12V battery was lit (see picture below). The dealership have said it was a technical glitch (no s&!t Sherlock) & that I should monitor it. Is this likely to happen again? I live in a rural area where most roads aren't lit - I'm very not happy about the prospect of losing my lights driving around here! Battery fault symbol is no longer visible. I checked the battery connections and they were firm.

 

[GaryMG4]

Anyone lost lights whilst driving? I was driving in the dark (thankfully on a lit stretch of road) when my headlights & I think other external lights went out, & stayed out. I'm not sure what the dashboard indications were at the time (I had bigger things to think about - like seeing where I was going!) Pulling & holding the mainbeam stick towards me gave me lights again (until I could pull off the road safely & wait for daylight!) When parked up, I noticed the red fault symbol for the 12v battery was lit (see picture below). The dealership have said it was a technical glitch (no s&!t Sherlock) & that I should monitor it. Is this likely to happen again? I live in a rural area where most road aren't lit - I'm very not happy about the prospect of loosing my lights driving around here! Battery fault symbol is no longer visible.

Happened to me a couple of times but mine was 100% pilot error. I managed to switch the lights to off with that silly little switch on the stalk whilst going from dip to high beam (or reverse). Not a nice experience with Fenland roads with deep dykes just a few feet away parallel to the road.

 

[Coulomb]

Anyone lost lights whilst driving?

No. But I did have the 12 V battery die while the car was parked in my carport. There was a related trouble code, U1563(16), "The battery voltage less than 9V is detected" (along with a dozen others; they all cleared). My guess is that there is some sort of firmware glitch that occasionally prevents the DC-DC converter from coming in to charge the 12 V battery. With headlights on, and the very heavy drain of power steering, the 12 V battery won't last long.

My MG4 has been fine since; the 12 V battery seems to have survived the ordeal for now. I suspect I discovered it within 24 hours of the glitch happening. With all the useless bongs like "entering [new suburb name]" (an Australian special, it seems), it's a pity that there isn't a bong for genuinely important ones like no 12 V charging.

 

[OriginalBigAl]

It also shows the high voltage battery fault and the 12v battery charging at 12.1v so presumably the HV battery is not charging the LV battery hence the problem, so the problem lies a bit deeper than the 12v battery. I have had the HV warning flash up on mine briefly but not to the extent of the 12v being discharged. Whether its a glitch which goes away on re-start or reset/ 12v battery disconnect , specific software update, who knows? Driving these cars needs a new mindset and reading of the information that's available whilst behind the wheel. I never have the 12v charging screen up as default so it means relying on the other warning lights , and noticing them , to second guess a potential problem that might occur. I would have thought the HV warning light would have been accompanied by a bong and brief message, but , all to easy to miss.

 

[Lovemyev]

Anyone lost lights whilst driving? I was driving in the dark (thankfully on a lit stretch of road) when my headlights & I think other external lights went out, & stayed out. I'm not sure what the dashboard indications were at the time (I had bigger things to think about - like seeing where I was going!) Pulling & holding the main beam stick towards me gave me lights again (until I could pull off the road safely & wait for daylight!) When parked up, I noticed the red fault symbol for the 12V battery was lit (see picture below). The dealership have said it was a technical glitch (no s&!t Sherlock) & that I should monitor it. Is this likely to happen again? I live in a rural area where most roads aren't lit - I'm very not happy about the prospect of losing my lights driving around here! Battery fault symbol is no longer visible.

An experience like that, is once too many and not very nice in my book.
Honestly, I would go ahead and replace that 12 volt battery if it was my car, regardless of its age or milage covered.
Batteries are a bit like a light bulbsreally, absolutely fine one minute and gone the next !.
If you replace the battery and are unfortunate enough to have a repeat episode, then you have at least eliminated this process at the dealers.
12 volt batteries are really good at disguising internal problems, one minute they report they are 100% fine, then suddenly they just fail .
For this type of thing to happen, it would suggest total collapse of the 12 volt battery itself.
Or the battery has been totally drained, because it is not receiving any recharge going back into it.
But I do find it a little strange that the main beam head lights still worked though ?.
Maybe because everything else was turned off ?.
I would just bite the bullet and replace the battery.
Check the voltage across the battery with a volt meter ( if you have one ) when the car is powered down, you should have roughly 12 - 13 volts on a new battery.
Then boot up the car into READY mode and recheck the voltage again across the terminals with a volt meter.
You should now be seeing about 13.5 to 14.0 volts.
If so, you have confirmed that the car IS recharging the battery correctly.
You could carry out the same check on your current battery yourself ?.
At least this would prove if your car is charging correctly at least.

 

[LenEV2016]

This added to your motor fault is unacceptable, it sounds like you have a lemon and id be looking for the dealer to get it fully tested before returning it to you.
How long have you had the car

 

[Ezza]

No. But I did have the 12 V battery die while the car was parked in my carport. There was a related trouble code, U1563(16), "The battery voltage less than 9V is detected" (along with a dozen others; they all cleared). My guess is that there is some sort of firmware glitch that occasionally prevents the DC-DC converter from coming in to charge the 12 V battery. With headlights on, and the very heavy drain of power steering, the 12 V battery won't last long.

My MG4 has been fine since; the 12 V battery seems to have survived the ordeal for now. I suspect I discovered it within 24 hours of the glitch happening. With all the useless bongs like "entering [new suburb name]" (an Australian special, it seems), it's a pity that there isn't a bong for genuinely important ones like no 12 V charging.

Quite! I've had so many notifications for tyre pressure being low (by a smidge)

 

[Ezza]

It also shows the high voltage battery fault and the 12v battery charging at 12.1v so presumably the HV battery is not charging the LV battery hence the problem, so the problem lies a bit deeper than the 12v battery. I have had the HV warning flash up on mine briefly but not to the extent of the 12v being discharged. Whether its a glitch which goes away on re-start or reset/ 12v battery disconnect , specific software update, who knows? Driving these cars needs a new mindset and reading of the information that's available whilst behind the wheel. I never have the 12v charging screen up as default so it means relying on the other warning lights , and noticing them , to second guess a potential problem that might occur. I would have thought the HV warning light would have been accompanied by a bong and brief message, but , all to easy to miss.

I think there was bong but I would have missed any message (not able to read it quickly enough, even if I'd got over the shock quick enough to try!) It all happened v quickly, & unexpectedly.

 

[Ezza]

No. But I did have the 12 V battery die while the car was parked in my carport. There was a related trouble code, U1563(16), "The battery voltage less than 9V is detected" (along with a dozen others; they all cleared). My guess is that there is some sort of firmware glitch that occasionally prevents the DC-DC converter from coming in to charge the 12 V battery. With headlights on, and the very heavy drain of power steering, the 12 V battery won't last long.

My MG4 has been fine since; the 12 V battery seems to have survived the ordeal for now. I suspect I discovered it within 24 hours of the glitch happening. With all the useless bongs like "entering [new suburb name]" (an Australian special, it seems), it's a pity that there isn't a bong for genuinely important ones like no 12 V charging.

Would the code be traceable (if there was one)? At the garage maybe?

 

[Ezza]

This added to your motor fault is unacceptable, it sounds like you have a lemon and id be looking for the dealer to get it fully tested before returning it to you.
How long have you had the car

It certainly feels like I've got a lemon. I've had it 2.5 years now.

 

[Ezza]

An experience like that, is once too many and not very nice in my book.
Honestly, I would go ahead and replace that 12 volt battery if it was my car, regardless of its age or milage covered.
Batteries are a bit like a light bulbsreally, absolutely fine one minute and gone the next !.
If you replace the battery and are unfortunate enough to have a repeat episode, then you have at least eliminated this process at the dealers.
12 volt batteries are really good at disguising internal problems, one minute they report they are 100% fine, then suddenly they just fail .
For this type of thing to happen, it would suggest total collapse of the 12 volt battery itself.
Or the battery has been totally drained, because it is not receiving any recharge going back into it.
But I do find it a little strange that the main beam head lights still worked though ?.
Maybe because everything else was turned off ?.
I would just bite the bullet and replace the battery.
Check the voltage across the battery with a volt meter ( if you have one ) when the car is powered down, you should have roughly 12 - 13 volts on a new battery.
Then boot up the car into READY mode and recheck the voltage again across the terminals with a volt meter.
You should now be seeing about 13.5 to 14.0 volts.
If so, you have confirmed that the car IS recharging the battery correctly.
You could carry out the same check on your current battery yourself ?.
At least this would prove if your car is charging correctly at least.

I'm no technician so I think I should get down to doing these checks (since the dealership hasn't volunteered to do so). Or just buy a battery, as you say...

 

[Lovemyev]

I'm no technician so I think I should get down to doing these checks (since the dealership hasn't volunteered to do so). Or just buy a battery, as you say...

Here is a volt meter that will be ample for what you require and is less than a £10.

https://amzn.eu/d/h1kya3k

If you do decide to replace the battery, these people are used by the trade and offer a next day delivery service.

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[Martinonline]

The Fault symbol indicates failure of the 12V battery charging system. (See attached image.) The manual says that if the 12V battery is low then the car will switch off some systems, not specified, so still having headlights working is correct.

My own experiences with this battery charging failure, reported elsewhere, in October 2023 and July 2024 have not been repeated and the car has not had any non-campaign updates. I have not changed the battery. MG4 Trophy bought April 2023.