Low voltage battery discharging

[sandra54]

Car is a ZS Trophy LR, just under a year old.

We have started seeing messages that the "Low voltage battery needs charging, do not leave car more than 3 days unused." Or words to that effect.

Yesterday evening we parked up with the battery registering 13.8V. Later in the evening it was down to 13.0V, measured via the MG Smart app.

Now (lunchtime), it's down to 12.2V.

As far as we can tell, nothing we control is on. And the car hasn't been used since we parked.

Can anyone shed any light?

Nick

I had the same thing, the warnings started after I had to be rescued by the AA when it wouldn’t start. Taken to the garage where they charged the battery. The car continued to give the warning, back to garage, decided it was a sensor! The car was back into the garage overnight on 2 further occasions as the warning messages changed to “ pull over when safe to do so “ and something about unsafe something or other! before they replaced the 12v battery. Why it wasn’t replaced immediately I’ve no idea . No problems since.

Oh and they tried to blame the battery loosing charge on me forgetting to lock the car !. The locking of the car turns thing’s completely off?

 

[Trebor]

Car is a ZS Trophy LR, just under a year old.

We have started seeing messages that the "Low voltage battery needs charging, do not leave car more than 3 days unused." Or words to that effect.

Yesterday evening we parked up with the battery registering 13.8V. Later in the evening it was down to 13.0V, measured via the MG Smart app.

Now (lunchtime), it's down to 12.2V.

As far as we can tell, nothing we control is on. And the car hasn't been used since we parked.

Can anyone shed any light?

Nick

I have just taken delivery of a ZS EV long range. 7 days old 400 miles completed.
Left car standing on my drive with 85% battery charge for 5 day’s whilst on holiday.
12v battery flat when I returned. Unlocked car but wouldn’t power up or lock again.
Breakdown service called and measured 3v in battery. Charged it and all up and running again. Breakdown tech asked if I had any problems with the radio, which I had. Radio lost statons and wouldn’t work during long journey the day before being left. Breakdown tech said that it’s probably the radio that has a fault draining the battery. He thought it is a known problem that probably just needs an update. Car to be booked into dealership for investigation and repair. (Incidentally, radio working again after the recharge).

 

[Tim Green]

I have a friend who used to work at Rover, obviously many years ago and when making ICE cars. He says that there was a steady flow of faulty brand new batteries that had to be returned to the battery factory every month under warranty. So it is possible that some rogue batteries get through production and into everyday use where they cause problems.
I have used Tayna Battery co in London who will send out a new battery for next day delivery and it could be worth the £50 or so to do that rather than mess with MG warranty?

 

[Sinc]

I have just taken delivery of a ZS EV long range. 7 days old 400 miles completed.
Left car standing on my drive with 85% battery charge for 5 day’s whilst on holiday.
12v battery flat when I returned. Unlocked car but wouldn’t power up or lock again.
Breakdown service called and measured 3v in battery. Charged it and all up and running again. Breakdown tech asked if I had any problems with the radio, which I had. Radio lost statons and wouldn’t work during long journey the day before being left. Breakdown tech said that it’s probably the radio that has a fault draining the battery. He thought it is a known problem that probably just needs an update. Car to be booked into dealership for investigation and repair. (Incidentally, radio working again after the recharge).

Had almost exactly same problem..car 6 wks old 13 hundred on clock..had problems with radio cutting in/out..left unused 2 days battery state 73%..LV battery @ 3v..AA got me going..no probs since..battery currently showing 12.9v ...radio (dab) working much better...booked in for check this week...be interesting to hear their comments

 

[Sinc]

Taken onboard advice to fit a BM2 monitor but Amazon has many costing £18 to £40 +...any recommendations as to what make etc? Thanks in anticipation

 

[Pontyboy]

I've got exactly the same issue, identical, that's spooky.
I will ring MG cardiff tomorrow!!!

 

[Lovemyev]

Taken onboard advice to fit a BM2 monitor but Amazon has many costing £18 to £40 +...any recommendations as to what make etc? Thanks in anticipation

This is a popular choice of battery monitor, the guy in the video ( Matt ) is both an owner and trader in the motor trade.
In the video below, you can see it being installed and working, in the text below the video, there is an amazon link to the battery monitor for £21.00.
Hope this helps .

 

[Lovemyev]

Radio lost statons and wouldn’t work during long journey the day before being left. Breakdown tech said that it’s probably the radio that has a fault draining the battery. He thought it is a known problem that probably just needs an update.

When the radio act's up like this, it is locked into a constant loop of trying to reconnect / reboot itself, even when the car is not active.
Unless you break the cycle of it looping, it will keep trying and trying while draining the battery in the process.
This is likely what has completely fattened the 12 volt battery as the recovery guy has already said.
When the battery is almost complete flat and the car is connected to new or a recharged battery, it has now automatically reset the entire 12 volts system.
This is the reason why radio suddenly starts working again correctly out of the blue.
If the info unit / radio freezes, or is cycling in a loop and refuses to reboot correctly by holding down the HOME button for about 10 seconds, then disconnecting the negative terminal on the 12 volt battery, wait 15 minutes, then reconnect the terminal and tighten.
This function simulates / triggers a full reset of the entire 12 volt system.
It should now return the info / radio unit to it's fully working condition again, if not its a trip to the dealership.
Running the battery flat and then introducing a new / recharged battery achieves the same result but the hard way !.

 

[Trebor]

When the radio act's up like this, it is locked into a constant loop of trying to reconnect / reboot itself, even when the car is not active.
Unless you break the cycle of it looping, it will keep trying and trying while draining the battery in the process.
This is likely what has completely fattened the 12 volt battery as the recovery guy has already said.
When the battery is almost complete flat and the car is connected to new or a recharged battery, it has now automatically reset the entire 12 volts system.
This is the reason why radio suddenly starts working again correctly out of the blue.
If the info unit / radio freezes, or is cycling in a loop and refuses to reboot correctly by holding down the HOME button for about 10 seconds, then disconnecting the negative terminal on the 12 volt battery, wait 15 minutes, then reconnect the terminal and tighten.
This function simulates / triggers a full reset of the entire 12 volt system.
It should now return the info / radio unit to it's fully working condition again, if not its a trip to the dealership.
Running the battery flat and then introducing a new / recharged battery achieves the same result but the hard way !.

That’s enlightening. Thanks for the info.

 

[Trebor]

Had almost exactly same problem..car 6 wks old 13 hundred on clock..had problems with radio cutting in/out..left unused 2 days battery state 73%..LV battery @ 3v..AA got me going..no probs since..battery currently showing 12.9v ...radio (dab) working much better...booked in for check this week...be interesting to hear their comments

I’ll be interested to hear also.

 

[Lovemyev]

That’s enlightening. Thanks for the info.

Your very welcome .
We have owned two ZS EV'S now over the last few years, both Gen1 and Gen2.
Covered about 30,000 miles and witnessed a few of the common issues on both models.
We where one of the early adopters of the original ZS EV and the "Black screen of death" was a common issue, witnessed by many owners.
The info unit would randomly either freeze or completely black out or even crash.
This would happen when you where using the sat nav sometimes.
Loosing the screen and not the audio, or some times both !.
If I remember correctly, the original ZS EV had a windows based system and the in the facelift it is android based.
It's more stable in the facelift model, but it still has it's moments TBH ?.

 

[graham1311]

I have just taken delivery of a ZS EV long range. 7 days old 400 miles completed.
Left car standing on my drive with 85% battery charge for 5 day’s whilst on holiday.
12v battery flat when I returned. Unlocked car but wouldn’t power up or lock again.
Breakdown service called and measured 3v in battery. Charged it and all up and running again. Breakdown tech asked if I had any problems with the radio, which I had. Radio lost statons and wouldn’t work during long journey the day before being left. Breakdown tech said that it’s probably the radio that has a fault draining the battery. He thought it is a known problem that probably just needs an update. Car to be booked into dealership for investigation and repair. (Incidentally, radio working again after the recharge).

Having read lots of posts about 12v battery discharging, even when just sitting in car without ‘car ready’ activation, I’m unsure which is best option if just wanting to sit in stationary car for a period. Is it best to activate ‘car ready’ or to use ‘power off’ option under ‘car safety’. So far on my MG4 I’ve assumed ‘power off’ and that then listening to radio won’t have any significant impact on 12v battery? Also I’m unclear why, if the car is left for longtime and HV battery <50%, it might cause a dead 12v battery. If car is left locked, no lights in etc then what is draining the battery?

 

[JCFlippen]

Radio can flatten the 12v battery on any car not only MG. Ready just keeps 12v battery topped up and uses very little power from the HV supply.

 

[Lovemyev]

I would recommend if your are standing waiting around, then leave the car in ready mode.
Yes - if you have the car in standby mode the radio will work fine, but it will time out after about 10 minutes anyway.
Which I guess is a reminder to tell you to boot the car into ready mode?.
If you are waiting around for a while in the winter or a hot day, you will likely need the HVAC system running for heat / cooling.
The car needs to be ready mode for this to happen.
At least if your wait time is longer than you first anticipated, the 12 volt battery is continuing to charge when in ready mode.
No so in standby mode.

 

[GameZone]

I got the low voltage message even after charging the battery 100%. So it's either a bug or bad battery, but the multimeter told me it was 12.6 in standby earlier today. The dealer told me that I shouldn't worry about it, and that MG offers free help if the battery suddenly dies. The dealer said that MG would never replace the battery, unless proven defective. I might buy another battery from a quality manufacturer like Varta and replace it myself at some point.

 

[Gadget Geek]

I got the low voltage message even after charging the battery 100%. So it's either a bug or bad battery, but the multimeter told me it was 12.6 in standby earlier today. The dealer told me that I shouldn't worry about it, and that MG offers free help if the battery suddenly dies. The dealer said that MG would never replace the battery, unless proven defective. I might buy another battery from a quality manufacturer like Varta and replace it myself at some point.

If you measure the voltage in standby mode, you aren't measuring the battery voltage, but the top up supply from the traction battery. Disconnect the terminals and measure again.

 

[GameZone]

If you measure the voltage in standby mode, you aren't measuring the battery voltage, but the top up supply from the traction battery. Disconnect the terminals and measure again.

The car wasn't on and running. But I didn't disconnect the terminals.

 

[Sinc]

Had almost exactly same problem..car 6 wks old 13 hundred on clock..had problems with radio cutting in/out..left unused 2 days battery state 73%..LV battery @ 3v..AA got me going..no probs since..battery currently showing 12.9v ...radio (dab) working much better...booked in for check this week...be interesting to hear their comments

Update to my previous post. Car checked by dealer and as previously indicted by others, no problems found. They have asked that I keep a log of any warning messages on displays and keep an eye battery state. Did state that the chances are it will happen again, maybe one,two, five,ten days, weeks etc. Stated they are carrying out all sorts of tests to identify problem...are pretty confident the prob lies within the infotainment system but unable to pin down at moment. Asked how many of this problem type this year..60 was answer and that's just one dealership!!!

 

[Pontyboy]

I've had identical problems.
In for first service this week
Asked dealer to check battery.
Tells me it's healthy and that my problem is I'm not doing sufficient mileage!!!
I told him I didn't read any warnings when buying the car that it was only suitable for high mileage driving!!!
Not happy.
His solution was to sit for 15min every day in drive mode before leaving my drive. He says the battery system is the same for all makes of EVs.

 

[Gadget Geek]

Tells me it's healthy and that my problem is I'm not doing sufficient mileage!!!

His solution was to sit for 15min every day in drive mode before leaving my drive. He says the battery system is the same for all makes of EVs.

What a load of b*ll*cks!