MGS5 12 Volt Battery Issues

[SFPlatt]

Hi
I am no expert on EV technology, but having issues with the 12 volt battery on my MGS5. The car has little use so may not be used for a few days, and on two occasions the battery has been very low with the AA suggesting a long run of an hour to recharge it. The second time the battery was so low the car would not open. This time the AA attended showed me how to access the car with the key, put a charger on it and again suggested a long run. Last night after an 80 mile trip I was warned again of low 12 volt battery, but managed to get home. Checked the voltage this morning and 12.3 volts showing. Looking at some posts on other MG models it does seem this may be an issue. I did have a dashcam fitted but have disconnected this some time ago and still have issues. Can anybody advise or help in any way

 

[Ian Key]

Have a look at this thread

S

Thread 'MGS5 12V battery dead'

Dec 1, 2025

Has anyone else had a problem with the 12V battery becoming drained overnight? I returned my first MGS5 due to this problem and today I have had exactly the same problem with my replacement MGS5, arghhhhh.

• Shwd mae
• battery drain battery issue mgs5 replacement vehicle
• Replies: 97
• Forum: MG MGS5 EV Forum

 

[T1 Terry]

It's starting to look as if anyone with an MGS5 should invest in a 12V battery maintenance charger, a V2L plug and keep their 12V battery charged that way .... at least until MG extracts their heads out of the sand and recognise there is a problem.

It's a real shame that a good vehicle gets a bad rap because some engineers can't admit they screwed up .... only then will they look at a fix, but not before they actually admit something is wrong.

T1 Terry

 

[Ian Key]

I have one because the same was said about the MG4. But in the 2.5 years I had my MG4 and the 5 months since I've had my MGS5 the only time I used it was to jump start the girlfriends diesel car.

 

[Joningy]

Hi
I am no expert on EV technology, but having issues with the 12 volt battery on my MGS5. The car has little use so may not be used for a few days, and on two occasions the battery has been very low with the AA suggesting a long run of an hour to recharge it. The second time the battery was so low the car would not open. This time the AA attended showed me how to access the car with the key, put a charger on it and again suggested a long run. Last night after an 80 mile trip I was warned again of low 12 volt battery, but managed to get home. Checked the voltage this morning and 12.3 volts showing. Looking at some posts on other MG models it does seem this may be an issue. I did have a dashcam fitted but have disconnected this some time ago and still have issues. Can anybody advise or help in any way

Join the club @SFPlatt , there's quite a lot on the forum, including my thread

(12V battery drained in 48 hours whilst locked)​

Seems to be a fairly common problem, which as many have said MG need to get sorted!
Still unable to determine if altering the dash cam feed from permanent live to switched has made a difference.
Do like lots of us on this forum and beyond have done and buy a 12v battery booster jump starter pack (around £30 upwards) and keep it in an easily accessible place, NOTE, MG4 & MGS5 don't have easy access to the boot if the 12v auxiliary battery goes flat. My 2 years with the MG4 was totally trouble free, but with my MGS5 I've already used it 3 times, it's easy to use and can save a long wait for a recovery firm to get to you.
I also bought a cheap head torch, just in case "SODS LAW" allowed it to happen in the dark

 

[SFPlatt]

Have a look at this thread

S

Thread 'MGS5 12V battery dead'

Dec 1, 2025

Has anyone else had a problem with the 12V battery becoming drained overnight? I returned my first MGS5 due to this problem and today I have had exactly the same problem with my replacement MGS5, arghhhhh.

• Shwd mae
• battery drain battery issue mgs5 replacement vehicle
• Replies: 97
• Forum: MG MGS5 EV Forum

Thanks for the reply, looks like I am not alone with the issue. One disturbing issue is the local dealer is asking for £150.00 for a diagnostic, and after reading this and other replies no doubt nothing will be found. I have decided to check the voltage daily up until it is due to go for the diagnostic

Thanks for the reply, looks like I am not alone with the issue. One disturbing issue is the local dealer is asking for £150.00 for a diagnostic, and after reading this and other replies no doubt nothing will be found. I have decided to check the voltage daily up until it is due to go for the diagnostic

Have a look at this thread

S

Thread 'MGS5 12V battery dead'

Dec 1, 2025

Has anyone else had a problem with the 12V battery becoming drained overnight? I returned my first MGS5 due to this problem and today I have had exactly the same problem with my replacement MGS5, arghhhhh.

• Shwd mae
• battery drain battery issue mgs5 replacement vehicle
• Replies: 97
• Forum: MG MGS5 EV Forum

Join the club @SFPlatt , there's quite a lot on the forum, including my thread

(12V battery drained in 48 hours whilst locked)​

Seems to be a fairly common problem, which as many have said MG need to get sorted!
Still unable to determine if altering the dash cam feed from permanent live to switched has made a difference.
Do like lots of us on this forum and beyond have done and buy a 12v battery booster jump starter pack (around £30 upwards) and keep it in an easily accessible place, NOTE, MG4 & MGS5 don't have easy access to the boot if the 12v auxiliary battery goes flat. My 2 years with the MG4 was totally trouble free, but with my MGS5 I've already used it 3 times, it's easy to use and can save a long wait for a recovery firm to get to you.
I also bought a cheap head torch, just in case "SODS LAW" allowed it to happen in the dark

Hi thanks for the advice I am taking it to the local dealer but with all the comments on here clearly an issue that needs to be resolved. I plan to check the battery every day until it goes for a diagnostic and it will be interesting to see what they say, after wanting to charge me £150.00 for this work.

 

[Joningy]

Hi thanks for the advice I am taking it to the local dealer but with all the comments on here clearly an issue that needs to be resolved. I plan to check the battery every day until it goes for a diagnostic and it will be interesting to see what they say, after wanting to charge me £150.00 for this work.

I am obviously extremely luck with Penton MG in Salisbury, they have now had 3 goes at my 12v battery problem, telling me after the last 3 day investigation, it was my dash cam permanent live causing the 12v drain, I had a loan car for 3 days and on one occasion ordered and paid for a taxi to run my wife and I into the centre of Salisbury, NO charge.
Possibly because they know I'm interested in the even newer MGS6.

Hi thanks for the advice I am taking it to the local dealer but with all the comments on here clearly an issue that needs to be resolved. I plan to check the battery every day until it goes for a diagnostic and it will be interesting to see what they say, after wanting to charge me £150.00 for this work.

@SFPlatt , surely they cannot charge you for warranty work???

 

[MG Clive]

@SFPlatt , surely they cannot charge you for warranty work???

Unfortunately a garage can charge for diagnostic work, even if the fault is found to be under warranty.

It doesn't seem fair, and many dealers will try to absorb diagnostic costs somehow, but it can easily take 2 or 3 hour to find that a £25 sensor is at fault, and if that £25 sensor is under warranty, that, plus a small fitting charge, is what MG will pay for, so the initial diagnostic costs are either written off, or paid for by the customer.

 

[Joningy]

Unfortunately a garage can charge for diagnostic work, even if the fault is found to be under warranty.

It doesn't seem fair, and many dealers will try to absorb diagnostic costs somehow, but it can easily take 2 or 3 hour to find that a £25 sensor is at fault, and if that £25 sensor is under warranty, that, plus a small fitting charge, is what MG will pay for, so the initial diagnostic costs are either written off, or paid for by the customer.

Didn't know that Clive!
Guess I'm lucky having an excellent main dealer in Penton MG, I'll push their excellent service.
Seems to me it may be worth travelling a bit for excellence.

 

[LaS]

There is several posting regarding 12v battery issues so i just choose this one and share my experience with my 12v battery: 2 weeks ago it was -20 where i live (Close to Oslo/Norway). My S5 was parked for 5 days and when i tried to use it it was totally dead. I measured the 12v battery, it was 2.9v. I was 100% sure it was dead and not usable anymore. But no, even if my homecharger did not manage the dealer did charge the battery and now 2 weeks after it still works fine. The dealer adviced me to charge the 12v regulary with a home charger because it is so much communicarion going on when parked who drain the battery. Things like communicating with the app, searching for the key, and mybe sending important info to China, what do i know...