Flat 12v battery after 6 weeks

[bazza123uk]

I went away for 6 weeks and on my return the car was dead. Doors would not open or anything I called MG support who sent the AA and they found the hidden manual key slot and opened the door and bonnet. I have to charge the 12v battery to recover the car even though the main battery was 57%

 

[Ian Key]

Some of us have bought a lithium car jumper power pack which we keep in the glove box just in case we have the same problem. It only needs enough power to wake the car up as it will then charge the 12v battery from the main battery.

 

[bazza123uk]

Thanks. Can you please tell me what you bought

 

[Alb]

Have a look at this thread

Jump Starter Power Pack

Bought one of these a couple of days ago from Amazon: It has good reviews and is rated at 1500A peak so should be useful on both EV and ICE vehicles. Reduced by 29% at the moment so only £49.99 delivered with Prime (mine was delivered 6 hours after ordering!). Chances are I'll never need to...

www.mgevs.com

 

[tsedge]

I went away for 6 weeks and on my return the car was dead. Doors would not open or anything I called MG support who sent the AA and they found the hidden manual key slot and opened the door and bonnet. I have to charge the 12v battery to recover the car even though the main battery was 57%

While the car should charge the 12V battery periodically, in the manual it does recommend a procedure if you are going to be away for a long period if time. For more than a month, it suggests disconnecting the negative 12V battery terminal.

It may be that you have a bug and that the 12V is not being charged, a software update would fix that. Or you might have a weak 12V battery which would benefit from replacement.

 

[dawson2099]

Same issue. I've found the emergency key and slot under drivers door handle. Does this turn or what? Very close to the door. I push and nothing. I'll try some pliers but so close it might scratch door.

 

[PeteC]

Same issue. I've found the emergency key and slot under drivers door handle. Does this turn or what? Very close to the door. I push and nothing. I'll try some pliers but so close it might scratch door.

The slot is in a cover over the key hole. You use the slot to pop the cover off and then the key to open the door. The first part of this video shows it being done on a different MG but same idea applies:

How do I use the mechanical key? // 12V battery was dead

Trying to open the car today and neither of the key fobs work. Seems like an issue with the car. Car had around 50% charge 2 days ago Totally failing to finding where I put the mechanical key to see if that might bring it to life. Not seeing it in the manual other than how to get it from the...

www.mgevs.com

Edit: Just in case that helps, page 159 of the manual shows where the key should be placed to be near the sensor in the MG4.

 

[dawson2099]

Got it thanks. A concern that after just 8 days away the 12v battery is flat. Is MG Assist valid on all new cars for 12 months?

 

[DBedford]

If serviced by an MG approved dealer, I think so. Service Plan Quote

 

[PeteC]

Got it thanks. A concern that after just 8 days away the 12v battery is flat. Is MG Assist valid on all new cars for 12 months?

It's weird how some people get this problem. We recently left our Trophy for over 6 weeks and it was fine. I believe that MG Assist is valid for 12 months and gets renewed after that if you have services with the dealer. MG's site states Following on from your initial year's roadside assistance, when you take your car back to your MG dealer for every subsequent scheduled service, if you choose the option, you will receive a further 12 months’ MG Assistance free.

Edit: Just beaten to this by @DBedford

 

[Storm]

I read in a BYD forum in Australia this morning, that their 12V battery is not great, and fails in winter. That's an Australian winter, so around 4 degrees on a cold night in most places.

 

[Ian Key]

Got it thanks. A concern that after just 8 days away the 12v battery is flat. Is MG Assist valid on all new cars for 12 months?

Check the battery terminals are tight. They take them off for shipping and only push them back on occasionally forgetting to tighten them properly.

 

[dawson2099]

The slot is in a cover over the key hole. You use the slot to pop the cover off and then the key to open the door. The first part of this video shows it being done on a different MG but same idea applies:

How do I use the mechanical key? // 12V battery was dead

Trying to open the car today and neither of the key fobs work. Seems like an issue with the car. Car had around 50% charge 2 days ago Totally failing to finding where I put the mechanical key to see if that might bring it to life. Not seeing it in the manual other than how to get it from the...

www.mgevs.com

Edit: Just in case that helps, page 159 of the manual shows where the key should be placed to be near the sensor in the MG4.

Door open and now charging with key face up in the drinks holder - detail now moved to page 170 BTW. Back to the dealer in a couple of weeks so I'll add this to the list. Mentioned somewhere that there might be a continual battery drain - I do have the AA wireless plugged in but not lit up unless car READY - I'll post if there's an answer from the dealer. Nothing immediate happening on the car so I'll just wait until a little power builds up in the battery. Thanks again for the prompt response.

 

[PeteC]

Door open and now charging with key face up in the drinks holder - detail now moved to page 170 BTW. Back to the dealer in a couple of weeks so I'll add this to the list. Mentioned somewhere that there might be a continual battery drain - I do have the AA wireless plugged in but not lit up unless car READY - I'll post if there's an answer from the dealer. Nothing immediate happening on the car so I'll just wait until a little power builds up in the battery. Thanks again for the prompt response.

Does the manual now show that the key should be in the drinks holder? The manual I have shows it in the front of the centre armrest storage box (well, that's what it looks like to me!). Might be time to download an updated manual..

 

[dawson2099]

On closer examination I would agree with you - storage box

 

[Martinonline]

My Trophy does not have the indicated niche in the storage box. I was confused by the picture in the manual. I have 2 versions of the owner's manual:

MG4_EV_Owner_Manual.pdf; and
MG4_Owner_Manual_EN_compressed.pdf.

The first puts the picture on page 159/324 and the second on page 170/327. I do not know which is the later version.

 

[dawson2099]

My manual came with the car at the end of March - also no specific slot for the key simply a depression in the base of the storage box

 

[Vingnut]

Attention:
A 12v battery that have been completly drained is dammaged to minum 50% capacity first time and should be replaced as soon as possible no matter what.

 

[tsedge]

Typical causes of this problem:

• Car is missing module updates to fix 12V battery charging issues (particularly affects early cars).
• Battery is junk, replace, randomly affects some, maybe bad batches?
• Battery terminals loose, due to shipping and dealers not doing proper PDI.

 

[Grriff]

I have Honda Assist. Make sure you remind your dealer that the car will need to be registered with the AA and you will get documentary proof.