MG ZS EV - 12v battery issue at start-up

[Iain]

Don’t see the dash cams causing any problems as long as they are used with the car in ready mode. I.E. 12v battery being topped up by HV battery.

 

[Cocijo]

It’s worth checking when the camera feed is live - e.g when in ready mode. Some dash cams have a parked mode for monitoring when the car is locked and parked - this needs a constant live feed. Carcams don’t use a massive amount of power but will drain a 12v over time if constantly live. The fitter should be aware of this anyway

 

[Deltex]

Most EV's 12 volt battery have time limit when than might discharge, mostly because of the alarms and background software which must stay on drawing power, something like 2 months!
If you go away i/2 moths I would disconnect the 12 volt. Remember, open door when returning with the Key! Remember you can re change 12 v battery using an external source,ie jump leads etc.

The 12 is only the master switch for the main batteries to come on. So it will effect the door locking
system.

 

[Cocijo]

I think all batteries have a time limit for discharging

 

[Kithmo]

Hi Kithmo,
I hope your 12v battery will last until you trade in the car.
You have not said what type of battery it is but if it is not ”maintainance free” might be worth checking electrolyte levels and if necessary topping up with distilled water.

Hi Iain, thanks, I forgot to mention that the first two cells nearest the +ve post were down on electrolyte, not to the extent that any of the plates were showing though and I did top them up with de-ionised water before I charged it up. Fingers crossed that was the only problem, it's been ok since.
BTW It does say "maintenance free" on it but it has caps on for topping up, very confusing for the service technicians at the dealers I suspect, which is why they probably have never checked it at the services.

 

[Lovemyev]

very confusing for the service technicians at the dealers I suspect, which is why they probably have never checked it at the services.

Run out of time, to busy topping up the washer bottle !.
You can't expect to get ALL of your levels checked every year.
They are saving that for next years service.
There is very little to do anyway, you would at least expect to get that right at least.
But then again, NO !.

 

[Deltex]

The life of a Lead acid battery is usually 5 years for good performance, a 12 volt Gel is 7 years ( No top up required!)

 

[Cocijo]

The life of a Lead acid battery is usually 5 years for good performance, a 12 volt Gel is 7 years ( No top up required!)

Is that based on ICE use? Would use in an EV be any different? Perhaps less high rate discharging with no engine to turn over?

 

[Deltex]

Gel is high capacity battery used in no break electrical/electronic systems. Example small 12 volt battery 7AH used in an alarm systems in you house. You can though get 100 amp one, cost a "few!! Quid" Life 7 years at least,
Speak to MG garage for cost and advice. I used one in my Prius. But in 3 years as lead acid should be covered until then.

 

[Kithmo]

Is that based on ICE use? Would use in an EV be any different? Perhaps less high rate discharging with no engine to turn over?

Lower charging rate is not necessarily a good thing, sulphation of the plates and inconsistent electrolyte concentrations occur if the battery never gets geed up with a high charge now and then.

 

[Cocijo]

I was thinking more of how a 12v ice battery gets used. It turns the engine at start up and needs sufficient power to cope with this high rate short term discharge. Ice 12v tend to fail more often at engine start up when they’re under max load. In an EV the 12v doesn’t have to do this - they’re just really switching the HV - so I guess may last longer and need less power?

 

[MrG]

With regards to this 12v battery, I fully charged my car today and noticed that the 12v only went as high as 13/14v. Is that normal or should it get up to the max 16v marker?

 

[macd2401]

With regards to this 12v battery, I fully charged my car today and noticed that the 12v only went as high as 13/14v. Is that normal or should it get up to the max 16v marker?

That's about normal. You don't want it going up to the max, bad things can happen.

Happened on my bike, regulator went way higher than it should, the magic blue smoke escaped, and it got messy

 

[Mark Holmes]

With regards to this 12v battery, I fully charged my car today and noticed that the 12v only went as high as 13/14v. Is that normal or should it get up to the max 16v marker?

That’s normal MrG

 

[Davemac278]

It shows 5 blobs on 12v charged and 6 blobs close to 14v when car is charging the 12v when needed in ready mode.

 

[Lovemyev]

With regards to this 12v battery, I fully charged my car today and noticed that the 12v only went as high as 13/14v. Is that normal or should it get up to the max 16v marker?

Just to clarify, did you charge the 12 volt battery or are you referring to charging the HV traction battery @MrG ?.
When you boot up the car WITHOUT depressed the foot brake at the same time, you will only see the state of the 12 volt battery condition being displayed on the 12 volt battery gauge.
If you fully boot up the car to the READY condition, by pressing the foot brake at the same time as hitting the START button.
The car is now receiving a charge to the 12 volt battery via the large HV traction pack.
THEN you should see about 15 volts shown of the 12 volt battery gauge.
This is seen as two full white bars ABOVE the centre 12 volt mark ( six o'clock position ) on the gauge.

 

[MrG]

Just to clarify, did you charge the 12 volt battery or are you referring to charging the HV traction battery @MrG ?.
When you boot up the car WITHOUT depressed the foot brake at the same time, you will only see the state of the 12 volt battery condition being displayed on the 12 volt battery gauge.
If you fully boot up the car to the READY condition, by pressing the foot brake at the same time as hitting the START button.
The car is now receiving a charge to the 12 volt battery via the large HV traction pack.
THEN you should see about 15 volts shown of the 12 volt battery gauge.
This is seen as two full white bars ABOVE the centre 12 volt mark ( six o'clock position ) on the gauge.

I'd need to have another look to be sure of what the actual figure is then. It was after charging the main battery from my granny charger, not the 12v.

 

[Esi]

Hi, I’ve had to call MG Assist / AA out again because my 20 plate MG ZS EV won’t start (3rd time in 10 months). Main battery fully charged, its the 12V that keeps letting me down - not enough power to fire up all the start up checks, running lights etc that come on to get into ‘Ready’ mode. The car is booked in for first service in a few days, dealer is going to check the battery and the brake light switch, but has anyone else had this issue?? Otherwise, I love the car, but always worried every time I go to start it!

Hi
I have had the exact happenings. I have checked the battery at Halfords and it’s in top condition. I have also checked to make sure nothing was left on. I don’t have radio anymore as it reads disconnected.
I shall never buy an MG again. I had Nissan Leaf and it was faultless for 4 years then I bought the MG.
Esi