12V Battery charge low - do not park for more than 3 days.

[DrTom]

Just picked up my LR ZS and get the above message when I switch the car to ready and again when switch off.

When the car is in ready it says the voltage is 14,6V

Any ideas out there

 

[TonyP]

This should resolve itself when you charge the car. The main HV battery will charge the auxiliary battery whilst charging the car. This will even happens automatically when the car is turned off and and not connected to a charger if the main battery has enough charge. Would check that no interior lights have been left on. The 14,6V indicates that the battery is charging in ready mode. If the auxiliary battery is less than 12V when not in ready mode it suggests the battery is flat and requires charging.

 

[DrTom]

Just noticed that on the app it reports the battery as being 13.6V - will see if it disappears in a few days

 

[Lovemyev]

If you have the App running, you can check your 12 volt battery status, when the car is powered down.
Mine always displays the same 13.1 volts when the car is idle.
It will increase to about 14.4 volts when the car is in READY mode or when being driven.
This indicates that the car is delivering a charge to the 12 volt battery.
If you have one, bang it on a 12 volt smart battery charger for a few hours.
This should get rid of the 12 volt low warning.

 

[peterseddon]

Several places sell a small solar panel that you can put on the dash and plug into the OBD socket to keep the 12 V battery topped up over prolonged parking times.

 

[Timdevnewbie]

We had this for about a week when we collected our ZS EV Trophy SR and I was a bit worried but it went away of its own accord. All the time the screen was showing over 12v and between 13.8 and 14.0 in running/ready mode.

 

[joneda1]

If you have the App running, you can check your 12 volt battery status, when the car is powered down.
Mine always displays the same 13.1 volts when the car is idle.
It will increase to about 14.4 volts when the car is in READY mode or when being driven.
This indicates that the car is delivering a charge to the 12 volt battery.
If you have one, bang it on a 12 volt smart battery charger for a few hours.
This should get rid of the 12 volt low warning.

View attachment 8490

What App are you using? I wasn't aware of any App's for the HS +EV.

 

[Lovemyev]

What App are you using? I wasn't aware of any App's for the HS +EV.

Some of the recent MG models are equipped with the facility to check in on the car for various features and functions, via an App on your phone.
The HS PHEV does not have this function unfortunately.
But you can buy a third party 12 volt monitor device that will allow you to check on the condition of your 12 bolt battery from an App on your phone.

 

[Roldorf]

My car was parked for 6 weeks from the end of May, had no problems.

 

[PositiveTom]

On a similar note, I’ve got a question…

We’re on the Octopus Go tariff which gives us £0.09/kWh between 0030 and 0430.

So in light of this we’ve got our MG ZS EV (2019) hooked up to a granny charger and a timer socket. It comes on at 0030 and off at 0430 to make the most of the cheap energy.

Went to start the car this afternoon and the 12v battery gauge was lower than I’m used to. No errors popped up, but I was very aware of it.

Does the 12v battery drain when the charger is attached but not powered? If so that seems a design flaw. Anything I can do to remedy / account for this?

 

[TassieDi]

I'm gutted to find that my Mark 2 has AGAIN become a brick, the 12V battery must be flat again. This is after leaving it attached to the 7kW charger at home for only two days!!!! I think this is ridiculous. It is a brand new battery, it was replaced after a series of quick flattenings earlier in the year. The battery was tested by the service centre and found to be defective.

 

[Coulomb]

the 12V battery must be flat again.

I wonder if there is something wrong with the DC-DC converter. Do you see the auxiliary battery gauge go to 14 V when in ready? Maybe in the Mark 2 you get better than the Mark 1's 8-led display.

 

[TassieDi]

I wonder if there is something wrong with the DC-DC converter. Do you see the auxiliary battery gauge go to 14 V when in ready? Maybe in the Mark 2 you get better than the Mark 1's 8-led display.

Tks, I think it usually does, I'll check again when I get the car going again tomorrow.

 

[Rayz]

Tks, I think it usually does, I'll check again when I get the car going again tomorrow.

I think your find the blue reading is the Rectifier voltage not the battery. If you put the car on., without pressing the brake that is the real Battery voltage .

 

[scoobeesnac]

I'm gutted to find that my Mark 2 has AGAIN become a brick, the 12V battery must be flat again. This is after leaving it attached to the 7kW charger at home for only two days!!!! I think this is ridiculous. It is a brand new battery, it was replaced after a series of quick flattenings earlier in the year. The battery was tested by the service centre and found to be defective.

I also noticed this issue when connected to a Zappi mk1 - I have not noticed it at any other time or with our Zappi mk2. The graphic shows the 12v draining after a charge but still connected.

 

[TassieDi]

I also noticed this issue when connected to a Zappi mk1 - I have not noticed it at any other time or with our Zappi mk2. The graphic shows the 12v draining after a charge but still connected.

Thanks, that's what I'm now starting to think, it might be the charger [EO Hub 7/22kW, installed 2020]. The 12V battery was so flat I couldn't get it going myself with my SJS Jumpstarter. Called roadside assistance, he measured the voltage as Zero. Once he'd booted it up, all was fine, the traction battery immediately charged it up to 13.6V.
Now I've attached a little BT battery monitor [Century, it draws 0.1mA continuously itself] but because it is BT as soon as I walk out of the basement garage I lose connection. Still the initial data shows that the battery stays stable at 12.6V while the car is Off and not Charging.

 

[Tim Green]

It is a worrying thought that leaving the car connected to my Podpoint might allow the 12v battery to discharge. This does not happen when the Podpoint is in charging mode, but it might if the Podpoint is on but disabled, eg with the keyswitch? I wonder how I can test that?

 

[Coulomb]

I'm now starting to think, it might be the charger [EO Hub 7/22kW, installed 2020].

Do you leave that plugged in for hours when not charging? If so, that might be the problem.

Early Nissan Leafs, granted a totally different design, keep a computer running all the time that you have an EVSE plugged in, whether it's charging or not. They too have poor auxiliary battery charging, and there are many reports of the auxiliary battery going flat as a result. So the recommendation for Leafs is not to leave them plugged in (if possible) after they stop charging.

I notice that my Leaf can start charging any time without "waking it up" by opening or closing doors, but my MG ZS EV does have to be woken up. So my MG doesn't seem to be monitoring the plug except for about 5-10 minutes after charging ends. That suggests that the MG shouldn't be draining the auxiliary battery just from being plugged in without charging, but maybe it doesn't work that way.

Worth watching perhaps, especially now that you have a way of monitoring the battery voltage without disturbing the car (opening a door for example wakes up all sorts of computers, changing the auxiliary battery drain profile completely).

 

[Coulomb]

This does not happen when the Podpoint is in charging mode, but it might if the Podpoint is on but disabled, eg with the keyswitch? I wonder how I can test that?

If you have a multimeter with a millivolts (mV) scale, you can measure the voltage drop from battery negative to car chassis. This effectively uses the negative cable as a low value resistor, even though you can't measure its resistance. You can get a feel for how much one millivolt represents by turning on and off headlights. With the bonnet open and all doors closed, wait for the current to drop to a minimum; it may take 5-10 minutes. Compare that with and without the charging plug inserted (and not charging, obviously).

One problem with this technique is that your minimum voltage reading is about 0.1 mV, and with the small currents we're talking about (probably well less than one amp), it may be that you'll get no reading at all.

I don't recommend using the multimeter on a proper current range, as a typical multimeter is rated at 10 or 20 amps maximum. When the DC-DC decides to charge the auxiliary battery, it could output 50-150 A and blow the multimeter's fuse, if not fry it altogether.

Another possibility is a DC clamp meter. The problem with these is that they use a Hall Effect sensor, and these are notorious for their reading drifting with time. Here we want to measure small currents over many minutes, and unless you have a particularly good clamp meter, the drift will drown out the changes that you want to measure.

 

[Tim Green]

Yes I do have a multimeter, but on reflection I should be able to just measure the voltage at the 12v battery. If the dc/dc is running it should be about 14v, if not running it would be more like 13 or even lower. I will try that. The issue is when eventually I get a smart meter installed in the house and can use the cheap overnight electricity charges, I need to be able to turn on and off the Podpoint on a timed basis which is not possible on my old model, or via the car. So I was going to use a time switch wired across the keyswitch in the Podpoint.