MG ZS Aux Battery getting depleted

[javiermi]

A nearly new 12 V battery going bad is not unheard of. How are you measuring the battery voltage? Do you use a digital multi-meter?

I have a bluetooth module that is attached to the battery ( it only consumes 1 mA, so is unlikely to drain the battery), but I was actually double-checking with a digital multimeter

 

[Cocijo]

I'm not sure what do you mean "in ready". When I finish with the car, I just turn off the car - either with the door switch or remote. What other option is?

If you press the start button with your foot on the footbrake you should go to ready mode (you’ll see the word ready in green) if you make sure that if you’re sitting in the car or using anything you’re in ready you won’t drain the 12v battery as the HV will charge it. Of course when you’ve finished switch it off (although it can be left for hours in this state - e.g. camper mode…). The other option is start button without brake pressed this only engages the 12v battery which will drain quite quickly if you are using anything as its not being charged by the HV pack.

 

[LoneRanger]

Perhaps try a week without the front camera connected, and see if it still does it ?

 

[Phil Hayward]

My 12v battery is very poor, it will only run the radio for a few minutes on auxiliary.
I will try to get it replaced on its first service.
It is possible to measure the current by the voltage drop across across the negative battery lead. Anybody know the resistance of this cable?
I was told that it normal for the battery to flatten in Aux and not to use it.
Even at 10 amps it should do at least 6 hours.

 

[Coulomb]

Anybody know the resistance of this cable?

Not I. But it possibly changes from car to car. I would use a clamp meter or OBD2 dongle to calibrate it. Then you can use your multimeter on the millivolt range (if it has one) to check the current any time that the bonnet is unlocked. The most important time will be when the car is supposed to be off, then you can't use OBD2, and your hall effect clamp meter may drift over time.

 

[Stuart Wright]

[merged the two threads by the same OP on the same subject]

 

[Coulomb]

My 12v battery is very poor, it will only run the radio for a few minutes on auxiliary.

It sounds like you might have one of the bad auxiliary batteries. I think I read somewhere that it's only covered under warranty until the first service. It's not clear whether at the first service is covered, so it might be worth sorting it out sooner. If that's not convenient, you might be able to get two bookings for the same day, the first one for the free battery, and the second one for the first service

 

[Kithmo]

It sounds like you might have one of the bad auxiliary batteries. I think I read somewhere that it's only covered under warranty until the first service. It's not clear whether at the first service is covered, so it might be worth sorting it out sooner. If that's not convenient, you might be able to get two bookings for the same day, the first one for the free battery, and the second one for the first service

Auxiliary mode shuts off after 10 minutes anyway, even with a good 12v battery.

 

[macd2401]

If it is the battery that's duff, even if it is only a year old, I'd be tempted to ignore MG altogether, and get a decent branded battery online. Something like a Varta or Bosch, 5 year guarantee, and not totally wallet busting.

I know, we shouldn't have to. But for peace of mind, might be worth thinking about.

 

[Kithmo]

If it is the battery that's duff, even if it is only a year old, I'd be tempted to ignore MG altogether, and get a decent branded battery online. Something like a Varta or Bosch, 5 year guarantee, and not totally wallet busting.

I know, we shouldn't have to. But for peace of mind, might be worth thinking about.

I would too, an MG one may only have another 12 month warranty.

 

[javiermi]

I have put my charger in pulse repair mode for around 12 hours and seemed to do the trick: It has been around 12.9-12.6 volts for a couple of days now. Before it would go down in barely a ciuple of hours. I will keep an eye on it, though Nothing like this would have happened if the ZS have had a proper app to alert me when AUX battery was too low - why would MG UK decided NOT to have it, just eludes me. Is like handicapping the car for no reason at all!

 

[macd2401]

I have put my charger in pulse repair mode for around 12 hours and seemed to do the trick: It has been around 12.9-12.6 volts for a couple of days now. Before it would go down in barely a ciuple of hours. I will keep an eye on it, though Nothing like this would have happened if the ZS have had a proper app to alert me when AUX battery was too low - why would MG UK decided NOT to have it, just eludes me. Is like handicapping the car for no reason at all!

Many years ago, most cars came with a range of gauges, giving info like volts, amps, oil pressure, turbo pressure... and most people didn't have a clue what it all meant. As cars evolved, only proper enthusiasts paid any attention, so the manufacturers took them out. If you were a gear head, you retrofitted them.

This is the first car I've had in nearly 20 years that's even had a voltage meter for the 12V system. Everything else has made do with a warning light. We can (and have) bemoaned the lack of a vehicle app in the UK, but the reality is that the car as is probably displays more info to the end user than most ICE cars (certainly from the budget end of the market) for the last few decades. And it's info that the average user knows nothing about, and has no interest in. Be honest. How many average car users will have a code reader or diagnostic software? How many average users on here have an OBD dongle and software? Most people just want to get in their car and go where they want. And if the car breaks down, that's what recovery services are for. That's the market we have, because those are the users we've raised. ?

Mainstream users don't want to tinker, so manufacturers won't generally bother too much. Talk of the app mostly revolves around "I wish I could preheat" not "I wonder what bank 3, cell 2 voltage will do if I horse it down the next straight"

 

[Kithmo]

I remember being a bit shocked in 2010 when my first Prius didn't have a coolant temperature gauge. ?

 

[LoneRanger]

Pretty sure the ZS has a warning light, (goes in search of Handbook to check) ...

 

[javiermi]

Many years ago, most cars came with a range of gauges, giving info like volts, amps, oil pressure, turbo pressure... and most people didn't have a clue what it all meant. As cars evolved, only proper enthusiasts paid any attention, so the manufacturers took them out. If you were a gear head, you retrofitted them.

This is the first car I've had in nearly 20 years that's even had a voltage meter for the 12V system. Everything else has made do with a warning light. We can (and have) bemoaned the lack of a vehicle app in the UK, but the reality is that the car as is probably displays more info to the end user than most ICE cars (certainly from the budget end of the market) for the last few decades. And it's info that the average user knows nothing about, and has no interest in. Be honest. How many average car users will have a code reader or diagnostic software? How many average users on here have an OBD dongle and software? Most people just want to get in their car and go where they want. And if the car breaks down, that's what recovery services are for. That's the market we have, because those are the users we've raised. ?

Mainstream users don't want to tinker, so manufacturers won't generally bother too much. Talk of the app mostly revolves around "I wish I could preheat" not "I wonder what bank 3, cell 2 voltage will do if I horse it down the next straight"

So what's wrong to able to get that information if is already available to a car in another country?
Is just a matter of being able to choose what you can look at or not.
So for you it will be enough to just have the "bare essentials" when most cars of the same category have them?

Don't get me wrong I don't like to have lots of lights and switches lying around, but why not having a tool where you can look "under the boonet" as it where , if you wish to do so. Specially when it won't cost much to implement

 

[macd2401]

So what's wrong to able to get that information if is already available to a car in another country?
Is just a matter of being able to choose what you can look at or not.
So for you it will be enough to just have the "bare essentials" when most cars of the same category have them?

Don't get me wrong I don't like to have lots of lights and switches lying around, but why not having a tool where you can look "under the boonet" as it where , if you wish to do so. Specially when it won't cost much to implement

I never said I thought it was a good idea, only that the average car user these days isn't really interested in anything that is in any way technical. We've been on a downward path for presenting info to the driver for decades. The fact that there are data menus on the ZS is way more than I had on my last few cars. Hell, I know there are some superminis and city cars out there where you got the speedo, and that's your whack. There's a reason why aftermarket OBD apps are so popular, but they still don't represent the majority of vehicle users.

If memory serves, the lack of an app in Europe is entirely down to the privacy and data use laws in Europe. Compliance with that just to allow most people to switch their cabin heat on before getting in is probably not a priority.

 

[Iain]

Before replacing battery I would check all connections are tight. You can check on the 12v battery and also any obvious connection to it like earth connection to body. I would avoid touching any of the high voltage connections.
I also like to put a smear of Vaseline or copper grease on the 12v battery connections.

 

[Kithmo]

Before replacing battery I would check all connections are tight. You can check on the 12v battery and also any obvious connection to it like earth connection to body. I would avoid touching any of the high voltage connections.
I also like to put a smear of Vaseline or copper grease on the 12v battery connections.

Good point, IIRC there was someone who had an loose earth connection on the 12v, poor PDI.

 

[javiermi]

After some weeks trying to figure out what was the problem with the aux battery, I decided I had enough
Just received a battery tester( 18.78US $ 18% OFF|KW208 Car Battery Tester Charger Analyzer 12V 100 2000CCA Charging System Test Dropshipping|Car Battery Tester, Charging & Repair Tools| - AliExpress) that I bought from china for 17 pounds and it showed it needed replacing, so went to a car parts shop and bought an equivalent Bosch battery ( 100 pounds) and just replaced it. I would definitely recommend the tester
Now all I need to do is keep an eye on the battery ( I have the car most of the time in my driveway)