MG4 Dead !!

[siteguru]

ISMART won’t connect and so won’t do a Status sweep. The last time I did a sweep a week or so ago I remember seeing the 12v having about 12.4v charge

Just done a scan on my car and it shows 12.5V (and 0°C inside, -1°C outside).

 

[Deleted member 9909]

The 12v is at the heart of an EV...without out it, it is brain dead. Once my car went dead and the call out technician found that the infotainment module continued to erroneously draw power. Reset and 12v charger plugged in...never happened since

 

[Chr1sB]

You haven't had a dash cam fitted?

No it was for Apple CarPlay

 

[Chr1sB]

The 12v is at the heart of an EV...without out it, it is brain dead. Once my car went dead and the call out technician found that the infotainment module continued to erroneously draw power. Reset and 12v charger plugged in...never happened since

My infotainment Centre was having issues - ie no radio and Nav screen stopping every now and then albeit audio continued.

I also have the ‘failed drowsiness monitoring message’ and another that warns of a USB initiation failure (even with no cable in any of them).

Car is booked in for 17th to do these things and the undertray bulge and breather pipe replacement

 

[FiferMG4]

Am I right in thinking the 12v battery is only charged when the car is "on" or charging?
If so leaving it parked up for a number of days, especially in cold weather, will flatten the 12v battery so in the OP's case plugging the car into a charger will recharge it.

On p291 of the manual in relation to the battery, it says, “
Note: It is recommended to set the power mode to READY for more than half an hour every week to help extend the service life of the battery. When the vehicle will not be used for an extended period (more than 1 month), it is recommended to disconnect the battery negative terminal clamping pile head. Make sure that the vehicle power system has been turned off before connecting or disconnecting the negative battery cable.”

 

[Ian Key]

On p291 of the manual in relation to the battery, it says, “
Note: It is recommended to set the power mode to READY for more than half an hour every week to help extend the service life of the battery. When the vehicle will not be used for an extended period (more than 1 month), it is recommended to disconnect the battery negative terminal clamping pile head. Make sure that the vehicle power system has been turned off before connecting or disconnecting the negative battery cable.”

That's interesting and I guess the cold weather has shortened the time until the 12v battery goes flat.

 

[Deleted member 9909]

It should not go dead in 4 days even with the cold weather imo. Car batteries are designed to be more resilient than that. The note I added earlier indicated intelligent charging might kick in. I suspect something is drawing power erroneously tbh

A faulty battery is a different kettle of fish!!!

 

[Chr1sB]

Car was driven for about 20 miles on Wednesday- so only been out of use for 2.5 days really and whilst it is cold I certainly wouldn’t expect a 12v to go dead in that time unless there is a fault somewhere…. another …. Grrrr

 

[Sloucher]

It should not go dead in 4 days even with the cold weather imo. Car batteries are designed to be more resilient than that. The note I added earlier indicated intelligent charging might kick in. I suspect something is drawing power erroneously tbh

I wonder just how good the 12v batteries fitted as standard are? I think I'd be tempted to source a decent quality, higher capacity battery.

 

[Chr1sB]

Anyway - thanks for all your input .. AA man should be here within the hour so I’ll feedback what he does and says afterwards. Thanks again.

 

[Chr1sB]

If it was me I'd attach a battery charger to give the 12V battery a boost and see if that kicked it into life.

The above is what the AA man did. His portable booster pack not enough to start it as down to 3v and so needed his wagon to get enough power for the fob to work and open and ‘start it’. He left his wagon charging it for 10 minutes before I got in and moved the car to my charger where it is now plugged in. He said the car battery should re-charge the 12v. A scan just now shows it at 14v but am not sure I believe it !

He said that most EV flat12v batteries are due to leaving the car unlocked ie the ignition is still on, or an interior light or similar has been left on. I didn’t have any of these issues but he couldn’t do any diagnostics that would tell him what has caused the issue and suggests I need to see a dealer to try to find out and sort the problem.

Just to say too that on Wed afternoon the charge was at 64% when I left it and when fired up today it was at 52%. That’s some loss over 2.5 days; I won’t be leaving at an airport To go on holiday anytime soon, issue fixed or not !

 

[Jomarkh]

Do you mean 64% down to 52%?
Perhaps it was trying to charge the 12v battery as that was being drained by something.

 

[Chr1sB]

Just to add and FYI .. when ‘jumping’ the car the AA man attached the positive cable to the battery, but did not use the negative battery terminal. Instead he used a clamping point on the body somewhere down low in front of the battery for the negative cable.

 

[Jomarkh]

That is how you should connect to a dead vehicle but most people connect battery to battery

 

[Chr1sB]

Do you mean 64% down to 52%?
Perhaps it was trying to charge the 12v battery as that was being drained by something.

My bad - yes. Entry updated. Thanks

 

[Deleted member 9909]

Chris, when it is a bit warmer try the emergency key again. It should not need pliers on that key to open the door ...on the basis of when you need it have you always got pliers to hand....just saying

If it is still tough to use then the dealership should have a look at it when you are next in with the car imo

 

[someguy]

Chris, when it is a bit warmer try the emergency key again. It should not need pliers on that key to open the door ...on the basis of when you need it have you always got pliers to hand....just saying

If it is still tough to use then the dealership should have a look at it when you are next in with the car imo

Does the emergency key slot into the body of the key a different way so you can use it for leverage?

On our Ford you take out the key and the end of they key fits into a slot that’s exposed in the body of the key so you can turn it (I accept I’ve probably worded this badly).

 

[Chr1sB]

Does the emergency key slot into the body of the key a different way so you can use it for leverage?

On our Ford you take out the key and the end of they key fits into a slot that’s exposed in the body of the key so you can turn it (I accept I’ve probably worded this badly).

Not as far as I can see - or from what the manual says. I’ll get the garage to look into it when it goes in as it should turn as stated in a previous post

 

[TJWhiteStar]

My infotainment Centre was having issues - ie no radio and Nav screen stopping every now and then albeit audio continued.

I also have the ‘failed drowsiness monitoring message’ and another that warns of a USB initiation failure (even with no cable in any of them).

Car is booked in for 17th to do these things and the undertray bulge and breather pipe replacement

Maybe these issues are draining the 12v battery constantly and then the HV is trying to charge it up again but after a while the drain just got too much for it to top it up before the car died.12v runs all the ancillary functions so if infotainment draining quickly could have pulled it too low before it triggered the HV backup charge.

 

[Chr1sB]

Maybe these issues are draining the 12v battery constantly and then the HV is trying to charge it up again but after a while the drain just got too much for it to top it up before the car died.12v runs all the ancillary functions so if infotainment draining quickly could have pulled it too low before it triggered the HV backup charge.

May well be. I’ll keep an eye on 12v battery SOC until goes into garage and try to use the car every day so that the 12v keeps getting recharged