MGS5 12V battery dead

[dx4100]

Car worked fine this morning.

I think you are right @Ian Key It was probably my fault in the end. Hopefully this is the end of the issue for me. I have to say though be careful with you 12 v battery. It really didnt take much to flatten it.

 

[German Paddy]

Question: Would locking the car switch off the auxiliary systems that are powered by 12V battery?

 

[dx4100]

Not sure what you mean but once you lock the car everything should pretty much switch off with the exception of things like mobile device / sim card to communicate the cars status. At some point my car would go to deep sleep where this wouldn't work either. I presume it detects the 12 v battery getting drained and puts the car to sleep but I am guessing now. Haven't seent this lately.

The whole thing is a head scratcher to me. How a car with a massive battery can ever allow the 12 v to drain But here we are

 

[emmrecs]

The "dead car" scenario has happened to me this morning! I suspect it is a 12v battery problem since car would not unlock. Mechanical key allowed access but no response to sitting on the driver's seat, so AA called and on their way.

I now very much realise the reason for advice I've read here: I do have a battery booster pack but it's in the boot so inaccessible!!

So, first task once everything back to normal: find a new home for that booster pack at the front of the cabin.

And then contact the dealer with whom I have a service contract. This is not the selling dealer since they are some distance away.

UPDATE: AA came, tested the 12v battery, "4 volts at arrival" (stated in AA Breakdown Report). Quick boost (from AA Technician's equipment), car went into Ready Mode very quickly. No obvious "user error" to cause the drain (e.g., interior lights left on etc.)

Have since done two c. 30 mile journeys, with a stop of more than 2 hours between, no problems. When we arrived home the 12v Battery Status screen showed the voltage as 13.9. Car now plugged in to charge to 80% in cheap period (00:00 to 05:00). I wonder what tomorrow morning will bring???

Oh, and the battery booster pack is now sitting in the tray underneath the centre arm rest.

 

[Lovemyev]

Car worked fine this morning.

I think you are right @Ian Key It was probably my fault in the end. Hopefully this is the end of the issue for me. I have to say though be careful with you 12 v battery. It really didnt take much to flatten it.

As @Ian Key as already suggested, do yourself a big favour and invest in a 12 volt battery booster pack !.
A lower output pack is fine for an EV but if you have a ICE car in the family, then I would suggest going for one with a bit more umph.
Keep it under the drivers seat and then, if you DID have a repeat of this situation, you would not be stuck waiting on one of our friends from the rescue services.
You may not be as lucky next time and may be waiting a long wait for them to arrive, to do what you can do yourself in 5 minutes.
There are couple sensible purchases that many E.V. tend to make, when switching from an ICE car.
A 12 volt booster pack is right at the top of the wish list, followed by 12 volt smart battery charger maybe .
I have used mine about 4 times to rescue other people stuck with a flat battery, none of them driving an E.V. As of yet .
Put one on your list to Santa - You never know your luck @dx4100 .

 

[dx4100]

Mine is a lease via work salary sacarfice / Tuskers all inclusive thing. If you mess around and do something wrong then you can end up in a whole heap of trouble. The car comes with manafactuer AA resuce and warranty and then it falls back on Tuskers RAC resuce and their responsability to maintain and fix. It wouldn't be wise for me to play mechnanic with it all to be honest and risk making something my problem. Specially given there is an element of voodoo around these EVs and my understanding of them at the moment

Now for my own Skoda Kodiaq which I own and is now out of warranty and very much already my problem I am very much thinking of getting one Just so happens I have to swap out the 12 v in that today due to it aging

 

[TimothyN]

do yourself a big favour and invest in a 12 volt battery booster pack !

There is a bewildering array of choice on Amazon. Any particular recommendation?

 

[emmrecs]

There is a bewildering array of choice on Amazon. Any particular recommendation?

I have this one. Never yet needed to use it but, as noted in post #24 in this thread, it is now stored in the front of the cabin and so ready to use!

I can't remember how much I paid for it but it was certainly less than the price listed on that Amazon page!

EDITED: to correct the link!

 

[Lovemyev]

There is a bewildering array of choice on Amazon. Any particular recommendation?

I guess it depends on your budget really Tim ?.
They tend to get more expensive, when you go for a pack that has more storage battery power.
Storage power is not that important for EV's of course, but if you have friends or family members with ICE powered cars, then I would go for a more powerful unit myself.
Personally, I have the Halo Bolt Air unit that has a built in air compressor as well.
These are popular American produces and on the expensive side.
Had mine from QVC of all places on special offer deal, but they don't have any stock right now.
Noco boosters are popular choice and are readerly available.
Another unit used by some in the trade is the Topdon booster pack.
I will include a link for the 2025 model with 2500 Amps of storage power.
This is from TopDon direct as is on offer, but be quick !.
This IS over kill for a E.V. but it has the advantage that it will boost ICE cars and vans multiple times.
If you only want it to boost ONLY your EV and want something less expensive, then choose the smaller power unit.
It can never be too powerful, only under powered for an ICE.

Pardon our interruption...

 

[dicky ticker Dave]

This may or may not be relevant.I brought a Royal Enfield motorcycle new in 2023 the battery was manufactured in 2021 lasted a bout 14 months. The batteries MG use probably maybe? a couple of years old before installation. New batteries can have been hanging around for quite some time. As for parasitic drainage the alarm system is running 24/7 so if the battery collapse's the alarm and sleeping circuits will drain a duff battery. You’ll get 12 volts from a collapsed battery but no amps. (Just saying)

 

[dx4100]

I just went for a GOOLOO New GP2000. £33.99 on amazon.

I may never need it and its not that complex of a unit so I reckon this will do me just fine. Its got a good review on parkers although they were reviewing a slightly bigger unit.

NOCO is the best brand but your going to pay twice as much for it. Although they have a smaller one for about £60 which would be fine for an EV. Its a bit much for something you won't use much I think.

 

[Ian Key]

I went for the NOCO Boost Plus. I wanted a "known" brand as I'm very wary about cheap electrical items especially with rechargeable batteries. They must skip on quality and safety features to be that cheap. Look at the number of cheap e-scooters that have burst into flames while charging.

Yes it is overkill for an EV but invaluable for starting my friend's ancient diesel Fiesta a few time until I managed to persuade her to get a new battery.

That reminds me I must put it on its three monthly top-up charge.

NOCO Boost GB40: 1000A UltraSafe Jump Starter Power Pack – 12V Car Battery Booster, Portable Power Bank & Jump Leads - For 6.0L Petrol and 3.0L Diesel Engines : Amazon.co.uk: Automotive

Instantly start dead car batteries with 1000A of peak lithium power. Includes built-in power bank, LED flashlight, and safety features for foolproof use.

amzn.eu

 

[Alb]

I just went for a GOOLOO New GP2000. £33.99 on amazon.

I bought the smaller version just under 3 years ago and it's been perfectly fine (notwithstanding the fact I've never actually had to use it )

 

[dx4100]

Car still going strong today. I think its fair to say it was probably something I did

 

[LenEV2016]

I went for the NOCO Boost Plus. I wanted a "known" brand as I'm very wary about cheap electrical items especially with rechargeable batteries. They must skip on quality and safety features to be that cheap. Look at the number of cheap e-scooters that have burst into flames while charging.

Yes it is overkill for an EV but invaluable for starting my friend's ancient diesel Fiesta a few time until I managed to persuade her to get a new battery.

That reminds me I must put it on its three monthly top-up charge.

NOCO Boost GB40: 1000A UltraSafe Jump Starter Power Pack – 12V Car Battery Booster, Portable Power Bank & Jump Leads - For 6.0L Petrol and 3.0L Diesel Engines : Amazon.co.uk: Automotive

Instantly start dead car batteries with 1000A of peak lithium power. Includes built-in power bank, LED flashlight, and safety features for foolproof use.

amzn.eu

You've opened a big door there and I'm desperate to go through it, there is definitely a joke to be made

I am trying hard to behave but your not making it easy

 

[Ian Key]

You've opened a big door there and I'm desperate to go through it, there is definitely a joke to be made

I am trying hard to behave but your not making it easy

Yes I know the irony of running down cheap electronics and rechargeable batteries when I have a cheap Chinese EV

 

[emmrecs]

Car still going strong today. I think its fair to say it was probably something I did

Unfortunately, not so for me!

I didn't use the car yesterday, but checked several times during the day that it was still accessible (i.e., could be unlocked and started), no problem.

Checked this morning, dead again!

Thankfully, as previously reported, I now have the booster pack accessible at the front of the car so am about to test it out for its first ever use!

So, having informed my local MG dealer about the initial problem, I shall now make an appointment to have it checked, very carefully!

 

[dx4100]

Unfortunately, not so for me!

I didn't use the car yesterday, but checked several times during the day that it was still accessible (i.e., could be unlocked and started), no problem.

Checked this morning, dead again!

Thankfully, as previously reported, I now have the booster pack accessible at the front of the car so am about to test it out for its first ever use!

So, having informed my local MG dealer about the initial problem, I shall now make an appointment to have it checked, very carefully!

If the battery dies then simply jump starting it is only going to bring it back to life. Its not going to fully charge it back up. That will take a while.

I would suggest after boosting leave it on your drive way for a couple of hours in ready mode to give the 12v battery a really strong boost.

We haven't left ours unused for any length of time since having the flat battery issue. But when we first got the car we drove it and then left it on the driveway for a week and came back to no issues. So all this is very strange.

Tempted to not use mine over the weekend to see what happens. Currently its being used every day but only for a max of 10 miles most days. Thursday (I go to the office - 120 mile round trip) and weekends it tends to get more use.

 

[emmrecs]

If the battery dies then simply jump starting it is only going to bring it back to life. Its not going to fully charge it back up.

Agreed and understood!

Have to make about a 80 - 90 mile journey later today so will have plenty of opportunity to fully recharge the 12V battery.

And the booster pack worked brilliantly! Now about to phone my local MG garage!

 

[dx4100]

Here lies the problem though...

It's a 35Ah battery and most evs charge at around 8-12 amps (AI says so so it must be true, lol). So its going to take roughly 4-6 hours to fully charge that battery if my fag packet maths is right.

So even after going for a drive today maybe still give it a few more hours in ready mode on the drive. I parkerd my ICE car in front of it so I didn't need to worry about it being stolen etc.