Parasitic drain on 12V battery

[Joningy]

That is a new and very interesting approach, but if MG is capable of the 12v auxiliary battery being topped up from the HV traction battery whilst locked and asleep, why isn't it?

This leads me to think perhaps, what I was told that MG does NOT support this is correct, I'm thoroughly confused.

But meanwhile the small 12volt backup jump starter is proving extremely useful and practice for when it happens in the darkness!

I regularly used the ismart app on my previous MG4 without ever having a problem, so what is different to on my S5 to the MG4?

 

[marcbesty]

Thanks for all of the comments. Some of them far too technical for me .

AA boosted the car again on Saturday, left it on the drive in Ready mode for 2-3 hours, took it for a 45 minute drive and charged the car overnight.

Went to use the car this evening and got an error message as I opened the car saying battery is low. Kept it on the drive for an hour in Ready and then went for a 45 minute drive but still had the error pop up when I locked the car. I've got the car on charge overnight so hopefully that gives it some charge.

In terms of apps, I have the MG app and the car is connected to the Fuse Energy app. I get kicked out of the MG app whenever I log in after a few minutes guessing that is due to being logged in to the Fuse App.

 

[stevedee]

So this might be of interest.

I don't have a system battery problem, but I've been pulling data from the car via the API this evening and noticed this...

Note that the time between samples is 10 minutes, so you wont see the second-by-second complete picture of what is happening.

But look at the system battery column on the far right. When the battery drops down to some point below 12.3V, the car steps in and charges the system battery, from the traction battery, for between 10- 30 mins (...again, can't be more specific due to the 10min update interval).

The voltage then drops back below 14V (no longer charging) and slowly falls from 13V to 12.5V.

The important point here is that the car appears to be monitoring the system 12V battery, and topping it up with a short charge if it drops below some preset limit. It doesn't wait until the car's traction battery is being charged.

My guess is that cars which suffer from flat 12V batteries, have a problem with this auto-charging mechanism.

 

[Joningy]

So this might be of interest.

I don't have a system battery problem, but I've been pulling data from the car via the API this evening and noticed this...

View attachment 42666

Note that the time between samples is 10 minutes, so you wont see the second-by-second complete picture of what is happening.

But look at the system battery column on the far right. When the battery drops down to some point below 12.3V, the car steps in and charges the system battery, from the traction battery, for between 10- 30 mins (...again, can't be more specific due to the 10min update interval).

The voltage then drops back below 14V (no longer charging) and slowly falls from 13V to 12.5V.

The important point here is that the car appears to be monitoring the system 12V battery, and topping it up with a short charge if it drops below some preset limit. It doesn't wait until the car's traction battery is being charged.

My guess is that cars which suffer from flat 12V batteries, have a problem with this auto-charging mechanism.

So from this can we positively say the High voltage traction battery is definitely charging the auxiliary battery when it drop to or below 12.3 volts?
Knowing if this is correct, helps when my car goes in for diagnostic checks on Wednesday, I also suspect the charging system is possibly faulty.

As I mentioned earlier, I have emailed MG Customer Support and had an automated reply today, purely acknowledging receipt of my email, but no answer to my question asking if the HV traction battery actually charges the 12v auxiliary battery whilst locked and turned off.

 

[TimothyN]

Has a Chinese programmer used the expression "Not too shabby"?

 

[Lovemyev]

@emmrecs
Although I do use the App myself, I would say that my usage is what you might class as fairly normal ?.
At a guess, I would say an average of once every couple of days or less.
In cold weather, you may use it a couple of times in a day to turn on cabin heating etc.
But then I can go days, or sometimes a week without using it.
I would expected that your usage would have to be very excessive to cause a completely flat battery surely ?.
Like checking it every hour, seven hours a day !.
I mean, who the hell does that.
My wall box is a pre-smart unit, so there is no fear of any interaction between the box and the car.
I was cleaning my car at the weekend and had the hatchback and doors open for about 2 hours.
Therefore the electrics / modules where all alive.
The car was not in ready mode, so not putting any charge into the 12 volt battery.
The following morning, straight after boot up, I checked the 12 volt battery status.
It was still displaying 14 volts.

 

[decrep]

So from this can we positively say the High voltage traction battery is definitely charging the auxiliary battery when it drop to or below 12.3 volts?

I think so, you can see the traction battery drops at the same time as the system battery goes up. This is expected behavior even if MG deny it