MG ZS Aux Battery getting depleted

[javiermi]

Hi
I have had my MG ZS EV Exclusive since Dec 2019, and more than once I have found the Aux Battery ( 12V) fully depleted while parked in my driveway
I've noticed that in less than a week ( some times 3-4 days) the voltage ( I have a bluetooth meter attached to the battery) goes as low as 12V
The only thing I have ( besides original equipment) is a front camera, that is turned off when I power down the car
I go and charge the battery every week, otherwise I will be able to even open the car!
Is anybody suffering the same issue

 

[javiermi]

For some time I have had the car ( ZS Exclusive) parked in the driveway and found that every week I had to charge the 12v battery as its voltage was geting very low - the only thing I have plugged in is a dashboard camera ( and its plugged to a point that voltage is switched off when car is shut down). Yesterday I charged the car ( showing 13v) with my new OVMS box, and went to 11V this morning at 6:00 AM. I know that OVMS consumes some power, but this is ridiculous!
Have you guys noticed something like this?
I there something wrong with my car?

 

[Gomev]

Silly question but have you tried process of elimination, by removing the camera and then the OVMS just to make sure it isn't either one of them that's draining the battery.

Also what make is the battery, there were some duff ones.

 

[Kithmo]

You may already have a weak 12v and having something plugged in that draws power all the time like the OVMS is not helping.
I don't understand, what you mean by, "I charged the car ( showing 13v) with my new OVMS box" ?
How does the OVMS charge the 12v ?
You need to charge the 12v using a separate charger/conditioner to get it to full SOC.

 

[Cocijo]

For some time I have had the car ( ZS Exclusive) parked in the driveway and found that every week I had to charge the 12v battery as its voltage was geting very low - the only thing I have plugged in is a dashboard camera ( and its plugged to a point that voltage is switched off when car is shut down). Yesterday I charged the car ( showing 13v) with my new OVMS box, and went to 11V this morning at 6:00 AM. I know that OVMS consumes some power, but this is ridiculous!
Have you guys noticed something like this?
I there something wrong with my car?

Do you use the car switched on not in ‘ready’ that’s the most common cause of running down the 12v. Always have the car in ready when in use - the HV will then charge the 12v - no need to charge it separately. You should show c14v.

 

[LeoRBK]

You may already have a weak 12v and having something plugged in that draws power all the time like the OVMS is not helping.
I don't understand, what you mean by, "I charged the car ( showing 13v) with my new OVMS box" ?
How does the OVMS charge the 12v ?
You need to charge the 12v using a separate charger/conditioner to get it to full SOC.

I suppose @javiermi meant "measured the LV battery voltage = 13V on OVMS".

 

[TiMoleseyEV]

I installed OVMS last week. The 12v is stable at 12.4v at all times.

 

[Cocijo]

I installed OVMS last week. The 12v is stable at 12.4v at all times.

My ZS dash voltmeter shows 14v most of the time - is that a different thing?

 

[Coulomb]

My ZS dash voltmeter shows 14v most of the time - is that a different thing?

It's the same thing, but most of the time when you see that you are in ready mode, which means that the DC-DC is pushing power into the battery (charging it) till it reaches 14.X V. Even a very weak battery, even no battery at all, can show 14.X V when charged. It's when the battery isn't being charged, and preferably has had a few hours to settle down, that the voltage becomes a crude indicator of its state of charge, with 12.0 V being nearly flat and ≈12.8 V being fully charged.

 

[Kithmo]

My ZS dash voltmeter shows 14v most of the time - is that a different thing?

Try it in ACC mode, nothing switched on.

 

[javiermi]

You may already have a weak 12v and having something plugged in that draws power all the time like the OVMS is not helping.
I don't understand, what you mean by, "I charged the car ( showing 13v) with my new OVMS box" ?
How does the OVMS charge the 12v ?
You need to charge the 12v using a separate charger/conditioner to get it to full SOC.

My bad, I should have said: "I charged the 12v battery with my OVMS box installed". I did use an external charger

 

[javiermi]

Silly question but have you tried process of elimination, by removing the camera and then the OVMS just to make sure it isn't either one of them that's draining the battery.

Also what make is the battery, there were some duff ones.

I originally had the camera connected to a fuse which provided power ALL the time, but due to this switched to a fuse that only provides power when IN USE ( car powered on). Regarding OVMs, I did the installation the day before, so not 24 hours had passed since, so have had no time to test
Th battery is the orginal SAIC 62A battery

 

[javiermi]

Do you use the car switched on not in ‘ready’ that’s the most common cause of running down the 12v. Always have the car in ready when in use - the HV will then charge the 12v - no need to charge it separately. You should show c14v.

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?

 

[javiermi]

Try it in ACC mode, nothing switched on.

I think you are missing the point: I open the door, open the trunk and check the battery , and is low, there is NOTHING switched on. Also, the ( 12V) battery gets drained when the car is actually turned off ( and locked)

 

[javiermi]

I have another question:
what are the chances the battery actually doesn't hold a charge?
Would that be covered by the car warranty?
I unplugged the charger for a few minutes, and it went from 13.10v to 12.5 in about 1-2 minutes
the only oher option would be that the charger ( a smart 8A one) is actually not properly charging the battery

 

[LeoRBK]

I have another question:
what are the chances the battery actually doesn't hold a charge?
Would that be covered by the car warranty?
I unplugged the charger for a few minutes, and it went from 13.10v to 12.5 in about 1-2 minutes
the only oher option would be that the charger ( a smart 8A one) is actually not properly charging the battery

The warranty statement says
12 V BATTERIES (vehicles registered after 03/01/2017) are covered till 1st scheduled service.
Additionally there is a small print,
**Note All12VBattery claims are limited to a maximum £100.00 pay out.

 

[LeoRBK]

I have another question:
what are the chances the battery actually doesn't hold a charge?
Would that be covered by the car warranty?
I unplugged the charger for a few minutes, and it went from 13.10v to 12.5 in about 1-2 minutes
the only oher option would be that the charger ( a smart 8A one) is actually not properly charging the battery

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?

 

[Coulomb]

I unplugged the charger for a few minutes, and it went from 13.10v to 12.5 in about 1-2 minutes

It's normal for a 12 V battery to drop from 13.x volts to 12.x volts in the minutes after it's no longer being charged. But with low loads (e.g. key off, just doors open, that's still a lot more than no load at all with computers woken up), I'd expect a fully charged battery to read about 12.6 V. So yours isn't too far off.

The best test is with very minimal loads, that means no doors open for at least 10 minutes. That means you have to have the bonnet open in advance of your measurement; opening the doors to get to the bonnet pull lever will disturb the test. Even being near the car with the key fob in your pocket will be using power. It's also better if you wait half an hour, for the battery voltage to settle, so the effects of the most recent charging (from ready mode) or discharging (from any activity) have faded.

 

[javiermi]

Coulomb thanks for the tips

 

[javiermi]

The warranty statement says
12 V BATTERIES (vehicles registered after 03/01/2017) are covered till 1st scheduled service.
Additionally there is a small print,
**Note All12VBattery claims are limited to a maximum £100.00 pay out.

So it seems I'm out of luck, as I already had the first service in December 2020.
My charger has a mode called "repair", I may give it a go