ZS SR battery drop off

[swordfish215]

Hi All

After owning my standard range for about a month now, I noticed that when the battery get to about the high 40% mark and the car is left at work for the day or overnight for example when i return the battery has lost between 8 - 14% of the battery.

This first time I just thought it was me forgetting how much charge I had, the second the temperature was pretty low so I put it down to that, but this week it’s certainly not down to weather and it still dropped by 10%

I was wondering if some cells in the battery might be faulty? Or is it because it’s new and just working things out.

Anyone else have a similar issue?

 

[Alb]

It isn't normal. Have a look at this thread:

50% battery drop while parked

Hi, we picked up our new MG ZS Saturday. Monday my wife drove to work ~20 miles, she parked at work with 80% battery left, 7 hours later when she left work the battery was at 30% and by the time she got home it was 20%. Is this normal? or is it because it's so new.

www.mgevs.com

 

[Hotlush]

Sounds like there may be some kind of vampire drain.

To rule out the obvious; do you have a hard wired dashcam?
Is the radio/multimedia definitely switching off?
Did you lock the doors?

 

[swordfish215]

It isn't normal. Have a look at this thread:

50% battery drop while parked

Hi, we picked up our new MG ZS Saturday. Monday my wife drove to work ~20 miles, she parked at work with 80% battery left, 7 hours later when she left work the battery was at 30% and by the time she got home it was 20%. Is this normal? or is it because it's so new.

www.mgevs.com

I did read through the post earlier, but battery pre-heat is definitely off and the post doesn’t seem to suggest much more apart from obvious stuff,

It’s certainly odd

 

[swordfish215]

Sounds like there may be some kind of vampire drain.

To rule out the obvious; do you have a hard wired dashcam?
Is the radio/multimedia definitely switching off?
Did you lock the doors?

No dash cams or anything wired in, I once thought possibly I didn’t lock the car and radio was left on, so I’m so concise off this and always check the radio has gone off when I lock the car.

But like I a sad said it always a the same roughly battery percentage, higher 40’s

I do check the car via the app, would that cause and sudden drop off?

 

[Mihir]

I've got a SR too. Haven't really made note of this but now that you have mentioned this, ill keep an eye out and keep you posted.

 

[r0b1n68]

I noticed the same issue when I received mine. I talked about it here in this thread

Didn’t really found an answer. But I noticed the range dropped less quickly under 20%.
A BMS update will resolve the issue I think

 

[Lovemyev]

I once thought possibly I didn’t lock the car and radio was left on, so I’m so concise off this and always check the radio has gone off when I lock the car.

We now have a Trophy LR after owning a Gen1 ZS EV for over two years.
On the original ZS EV the info unit would completely close down, when the car was shut down.
The face lift is different, as the info unit remains active when the car is closed down.
You are able to leave the car and the info unit remains active !.
Only when you lock the doors does the info unit close down.
However, I noticed that if you are sitting in the car ( with it closed down ) after a 10 minute delay, the info unit will then close down.
A timed delay feature on the new face lift model it would appear.
This may interest you ?.
I was cleaning my car yesterday and it had been closed down for at least 30 minutes.
I reached inside and decided to clean the finger prints from the screen of the head unit.
When I touched the screen with one of my fingers ( which had been closed down for a while ) it made the "Bleep" touch sound you get when you are selecting touch buttons on the screen.
I only did it once, but that suggests that although the info unit is closed down.
Some power is still being supplied in order for the screen to give out the audio touch warning that I received.
I tried pressing the screen again, but no sound was omitted on the second attempt.

 

[swordfish215]

I noticed the same issue when I received mine. I talked about it here in this thread

Didn’t really found an answer. But I noticed the range dropped less quickly under 20%.
A BMS update will resolve the issue I think

Thanks for this

 

[Lovemyev]

Just the thought of having a BMS update applied, sends a cold shiver down my back to be honest.
After the issues some owners of the Gen 1 ZS EV experienced.

 

[r0b1n68]

Just the thought of having a BMS update applied, sends a cold shiver down my back to be honest.
After the issues some owners of the Gen 1 ZS EV experienced.

The SR models BMS is clearly messed up at some point. Once you reach less than 40% battery, it’s drops really fast, then at about 20%, you will not lose any battery before a loooong time.
Weird, but I think it’s because of the LFP battery, it’s a completely new technology for MG

 

[r0b1n68]

Example : I drove 12km back from work yesterday night, and my car went from 41% to 23%. No way I consumed that much for my commute.
This drive (my commute) consumes usually 5% maximum with heating, and 3% without HVAC or heating.

Today, this morning, I drove 12km to work, and then my car consumed… 0%. It stayed at 23%.
I used the remote climate function from the app this afternoon to cool the cabin, and the car dropped to 22%.

I drove back 12km to home this afternoon, and it only consumed 1%, from 22% to 21%.
I had HVAC at the lowest temperature, there is NO WAY, that only consumed 1%.

I think MG really needs to do a BMS update real quick to adress that

 

[BarryH]

I think the explanation is fairly simple. Its a temperature thing. If you've driven the car you will have warmed the battery simply by drawing current from it and how you drive and for how long and the ambient temperature are all contributing factors/ Then you park up the car and possibly overnight when the ambient temperature will have dropped consideribly at this time of year with sunny days and clear chilly nights so that the battery, which don't forget stores the energy chemically, will have cooled and thus the voltage will have dropped a few volts and thus the battery percentage reading which is based on the voltage the BMS sees will have dropped. Youve not actually lost the energy it is simply at that at that lower tempiture the energy is slightly less accessable until the battery chemestry warms up to its optimum operating temperature. I had the the oposite effect this morning. When I checked my range this morning before i packed the the car for a trip today I had 132 miles but whan i set off a couple of hours later at aroun 11 am I noticed 5 minutes in to the drive that I had 133 miles range. in that 2 hours the mist had burned off and I was in full sun.

 

[r0b1n68]

I think the explanation is fairly simple. Its a temperature thing. If you've driven the car you will have warmed the battery simply by drawing current from it and how you drive and for how long and the ambient temperature are all contributing factors/ Then you park up the car and possibly overnight when the ambient temperature will have dropped consideribly at this time of year with sunny days and clear chilly nights so that the battery, which don't forget stores the energy chemically, will have cooled and thus the voltage will have dropped a few volts and thus the battery percentage reading which is based on the voltage the BMS sees will have dropped. Youve not actually lost the energy it is simply at that at that lower tempiture the energy is slightly less accessable until the battery chemestry warms up to its optimum operating temperature. I had the the oposite effect this morning. When I checked my range this morning before i packed the the car for a trip today I had 132 miles but whan i set off a couple of hours later at aroun 11 am I noticed 5 minutes in to the drive that I had 133 miles range. in that 2 hours the mist had burned off and I was in full sun.

I really don't think the temperature is the cause. My garage is between 18 an 19 celsius, and we have around 25 celsius here during the day. The car is parked right under the sun.

I observed this phenomenon every single time my car reaches 40%. It's never different.
Then when you are around 20% or a little more, the SoC doesn't drop the way its should.

My guess is a "beta BMS" or something, because the LFP tech is too new to MG, so they need to adjust it and update it to have a good and reliable BMS.
Now I don't really have a problem with the car behavior, because I know it and I know how it reacts, but it's really annoying to not having a "true" SoC when the battery goes under 40%

 

[swordfish215]

Slight update from yesterday,

Battery reached 48% (80-90Miles GOM)when i parked up at work, this is when I would expect the battery to suddenly drop, Car was left for roughly 8/9 hours and the battery was exactly the same when i returned to the car, 12mile drive home and was at 49% battery when i got home with a similar GOM.

Considering i was considerably cooler i was very surprised, just to add the information my trip to work would usually cost me between 8-10% battery (on the way to work) and the return will only use 2-4% battery due the nature of the roads.

the only difference i can honestly see is that i charged the car at about 80% but set the schedule charge for 5 hours, as someone had mentioned about leaving it plugged in for a period of time at 100%, also i have driven predominantly in normal mode as opposed to ECO

I will update this post next week and see if the issue has magically disappeared

 

[r0b1n68]

Hi! A little update today about the loss of range while the vehicle is parked. I parked my car at 9.30am, it was at 50%. At 12.00, it went down to 47%, and then at 2pm, it went down another time to 44%.

I don’t really understand why the SoC is dropping that fast while the vehicle is parked, it’s not that cold outside, around 11°c.
I left my vehicle parked with -2° Celsius a few days ago, and I had no range drop when the SoC was between 100% and 60%.

I think a BMS update is really needed now to adresse that, this is problematic.
With 50% left, I could have finished my week without recharging, but no I won’t make lt
Not a problem because I have a wallbox to charge at home, and I can charge at work, but the SoC dropping that much is a problem

 

[rpannell]

I suspect that the this is a measurement error rather than an actual loss. On that basis that energy is neither created or destroyed, the approx 3kWh that you appear to has lost would have to go somewhere - probably as heat. Assuming that your battery has not got hot whilst the car was parked, then it is much more likely that the change in SOC is a measurement change rather than an actual loss. Just my thoughts, unless your battery is really getting hot as it loses the 3kWh