MG ZS EV 2020 multiple warning lights

[LG10]

Hello, first time poster so apologies if this issue has been posted before or any mistakes

Got multiple warning lights which appear whilst driving, including:

ABS Fault
Stability control fault
Traction control fault
Hill descent fault
EPB system fault
Auto hold fault

Car is fully ready when I start car and fault appears after about 5-10 minutes of driving.

12V battery showing just under 14V whilst driving but under 12V when off.

Waiting on mg to get back in touch and going to disconnect 12V battery and reconnect but though I’d ask community see if they have seen issue or advise.

Car is a 2020 MGZS EV

 

[Gadget Geek]

Welcome to the forum.

Sounds like the 12 volt battery might need testing and replacing if not holding its charge. It's a common problem. If you use the search function, you will find a number of threads on it.

 

[LG10]

Welcome to the forum.

Sounds like the 12 volt battery might need testing and replacing if not holding its charge. It's a common problem. If you use the search function, you will find a number of threads on it.

Thank you!! I was thinking potentially 12V battery, any idea what it should be when car is off? I was led to believe over 12V.

Thanks for advice on threads search also.

 

[Gadget Geek]

When the car is on, you will be reading the charge propped up by the traction battery. It is normally around 13 volts when the car is off.

 

[Coulomb]

It is normally around 13 volts when the car is off.

I would say that when it's settled for an hour or several, it will be in a range from about 11.8V (dead flat) to about 12.8V (full, nearly new). The Mark 1 battery voltage gauge has a resolution of 1.0V per light, so it's pretty useless except for the grossest state.

Interesting that your problems only start some time after you start driving. It's possible that the auxiliary (12V) battery is tired but still ok, as it starts the car. In that case it could be noise on the 12V wiring, or in the CAN bus. The former could be from a faulty DC-DC, or a wiring fault, e.g. a fuse that is not making good contact. These would unfortunately be quite tricky to track down.

But I agree with others that the most likely problem is the auxiliary battery just being too old. It needs to be in reasonable condition to smooth out glitches on the 12V bus caused by carious loads coming on and off. The DC-DC converter can't react immediately to sudden load changes, so the auxiliary battery acts as a kind of buffer.

I have a feeling that the Mark 1 doesn't charge the auxiliary battery when off, or maybe it dies but not often enough. If so, that would cause the auxiliary battery to degrade more quickly, especially if the car doesn't get used sometimes for days at a time. Four years isn't unusual for a 12V lead acid battery to die, but some cars, especially EVs, can get six or more years of life from them.

 

[AAA mileage club]

I'm sorry to be the typical it-support "have you tried to turn it off and turn it on again?" kind of guy but are you confident that you always as the first thing after entering the driver's seat have the brake pedal pushed firmly? Then pressing the start button and wait for the plings and plong and display to read ready? And only then taking the foot off the brake pedal (unless you need to set it in D or R gear first, of course)?

 

[LG10]

I'm sorry to be the typical it-support "have you tried to turn it off and turn it on again?" kind of guy but are you confident that you always as the first thing after entering the driver's seat have the brake pedal pushed firmly? Then pressing the start button and wait for the plings and plong and display to read ready? And only then taking the foot off the brake pedal (unless you need to set it in D or R gear first, of course)?

I believe so, never had an issue in 2 years, will update the forum once sorted(hopefully) thanks for the reply

I would say that when it's settled for an hour or several, it will be in a range from about 11.8V (dead flat) to about 12.8V (full, nearly new). The Mark 1 battery voltage gauge has a resolution of 1.0V per light, so it's pretty useless except for the grossest state.

Interesting that your problems only start some time after you start driving. It's possible that the auxiliary (12V) battery is tired but still ok, as it starts the car. In that case it could be noise on the 12V wiring, or in the CAN bus. The former could be from a faulty DC-DC, or a wiring fault, e.g. a fuse that is not making good contact. These would unfortunately be quite tricky to track down.

But I agree with others that the most likely problem is the auxiliary battery just being too old. It needs to be in reasonable condition to smooth out glitches on the 12V bus caused by carious loads coming on and off. The DC-DC converter can't react immediately to sudden load changes, so the auxiliary battery acts as a kind of buffer.

I have a feeling that the Mark 1 doesn't charge the auxiliary battery when off, or maybe it dies but not often enough. If so, that would cause the auxiliary battery to degrade more quickly, especially if the car doesn't get used sometimes for days at a time. Four years isn't unusual for a 12V lead acid battery to die, but some cars, especially EVs, can get six or more years of life from them.

I’ll get a battery health check see if that comes up with anything. I’ll see what MG say also, appreciate the reply and will update once sorted

 

[Lovemyev]

TBH - Maybe its fair to say, that at almost four years old and a covered mileage of 60,000 miles, the car has cycled that 12 volt battery ? a good number of times by now.
Has it just been a battery too long ? and therefore replacing it would be a good starting point regarding the random warning signals you are witnessing ?.
It would be the likely starting point for the dealer I think.

 

[MPC51]

It sounds to me like a faulty ABS sensor. I have a 2020 ZS EV now but my last car was a VW Tiguan and I had 3 sensors fail me. The EPB, hold function, and a couple of others were disabled like yours. The warning lights would come on after a couple of minutes driving and would sometimes go off later

 

[mick coats]

I have a similar problem, so will try replacing the 12V battery. Can I get my local garage to supply and fit a good quality battery, or does it have to be the MG dealer?

 

[fred12345]

any garage should be able to do it for you but before you do, check whether it needs replacing. your garage should be able to check that for you

 

[mick coats]

Thanks, I'll follow that up.

 

[mj224]

I also had a similar occurrence on my 3-year-old ZS EV. It drove OK, but all bells and whistles would not work. I carried on driving, parked, did my shopping, and on return, all worked as it should.

That was maybe 6 weeks ago, had no problem since....gremlins I think..

 

[decrep]

Hmm Ice motors need a battery capable of cranking the starter motor in cold weather.
This a hard ask, and needs a battery designed to do it.
Am I right in assuming the EV 12V battery is only powering electronics and maybe a few solenoids?
If so the optimum battery for this will be different to that needed by an ICE car. More that likely your average garage won't stock these, although of course they will still work.
There are specialist battery shops around, that may have a clue to the best battery and be cheaper than MG.

 

[fred12345]

Hmm Ice motors need a battery capable of cranking the starter motor in cold weather.
This a hard ask, and needs a battery designed to do it.
Am I right in assuming the EV 12v battery is only powering electronics and maybe a few solenoids?
If so the optimum battery for this will be different to that needed by an ICE car. More that likely your average garage won't stock these, although of course they will still work.
There are specialist battery shops around, that may have a clue to the best battery and be cheaper than MG.

I am still in the last century regarding 12V batteries ...
here is one article from one of the manufacturers and another general article

The role of 12 Volt batteries in electric vehicles

In modern electric cars, Starter batteries step in when the main battery fails or switches off, to support electrical consumers and systems.

batteryworld.varta-automotive.com

What are the types of 12V Batteries? - E-XTEQ

Batteries come in all different sizes, shapes and uses, and this is no different for 12V batteries which is one of the most common ones.The 12V batteries used for transportation, such as in vehicles, boats or other, have different sizes influenced by their use and the amount of amp-hour they are...

e-xteq.com

 

[decrep]

Well the first one is so wrong it's not funny, there's no way a 12V battery could step in when the main one fails. The 12V battery is there to run the electronics when the main battery is turned off.

I think a battery that's designed for camping, caravan fridge and lights, and charges by the car alternator. They should have a similar work load, although you may not need as much capacity.

Looks like they are "deep cycle" batteries, I think this means they are designed to go from fully charged to fully discharged. Not like a starter motor battery, short high current load, then topped up immediately.

 

[fred12345]

Well the first one is so wrong it's not funny, there's no way a 12v battery could step in when the main one fails. The 12v battery is there to run the electronics when the main battery is turned off.

? yes, I also went "WHAT???", had to read it again - they say it's to step in for "the uninterrupted function of safety critical systems" ...
...so you can listen to the radio whilst broken down in fast lane on motorway ...

 

[LG10]

Slight update, so haven’t had a warning light since the last time until today, drove 300/400 miles however it’s the first time I’ve had air con on since then and after 15/20 minutes of driving, warning light is back

 

[fred12345]

Slight update, so haven’t had a warning light since the last time until today, drove 300/400 miles however it’s the first time I’ve had air con on since then and after 15/20 minutes of driving, warning light is back

to catch up with earlier posts, my 12v battery shows 13.2V with the car off and after not using the car for about 12 hours.
if yours is below 12v, probably time to change it regardless of whether that causes warning lights or not ... at least you will discount one possibility if the warnings come back afterwards

 

[LG10]

to catch up with earlier posts, my 12v battery shows 13.2V with the car off and after not using the car for about 12 hours.
if yours is below 12v, probably time to change it regardless of whether that causes warning lights or not ... at least you will discount one possibility if the warnings come back afterwards

I’m planning on replacing my 12v battery this week also, but have got my car in to my, hopefully check wiring etc, anyone no if it’s a agm 12v battery already installed? Tried googling but just get brought to a load of Chinese websites with limited info, none of them say what type of 12v battery it is