MG ZS EV - Cold weather power drop off

[SRMiller07]

Hi, I'm just trying to work out if it's just me having some drop off in power availability with the gen 1 zs ev with this cold weather.
This morning (-5c) I set off on the school run with 50+ miles on the range and 4 bar showing on the battery. All seemed ok. Then I noticed after a mile or 2 that when accelerating it only peaked at 70% power. After dropping the first kid off I went on to drop the next off and the battery dropped to 3 bar and then I only had 60% power. After dropping the last kid off I cam home (around a 6 mile round trip) I noticed that the car would peak at 60% power and then drop to 50%. I got home and put the car on charge and it had 36% of the battery available!
I had this a week or so ago and found that if the first state of charge warning light came on I then had 40% peak power and would then drop off to 30% and the car could barely get to 50-55mph.
This time when I put it on charge I had 21% on the battery).
All this is happening on one trip and the car isn't being switched off in between. Just as the the charge drops off so does the power.
A bit worrying when I live in MK and need to pull out on to roads which are either 60/70mph in rush hour.
I get that cold weather can affect the battery but this seems more "pre-programmed" to happen at set states of charge and is linked to the external temp, rather than the actual temp of the battery, as I assume the battery would be a bit warmer towards the end of the journey?
My biggest grip is that there is now on screen warning to state that the power is being limited which would be very handy to know!
I do have the car booked in on 7th March to have this looked at and also to repair the drivers wing mirror which won't go back in when locked.
Just wanted to know if anyone else had something similar?
I believe the latest BMS is on the car from the last service (voltage dropped to 449 rather than the old 455?) and I can now charge on an AC without having to lock the car. Not sure if this has anything to do with it?
Thanks for any comments!

 

[N2STY]

I am pretty sure if you set off with 80+% of battery there would not of been a problem with only 50 miles left it's a bit close to power saving
What drive mode was you in?
Did you try the other modes?

 

[SRMiller07]

I am pretty sure if you set off with 80+% of battery there would not of been a problem with only 50 miles left it's a bit close to power saving
What drive mode was you in?
Did you try the other modes?

Hi, If the car is fully charged then there is no drop off and all seems normal.
However I did a round trip to Oxford (about 80ish miles) and did notice on the final bit of the trip the power was dropping off to 70%. That was just before christmas and I can't remember the temp but it was cold out. This leads me to believe it's the air temp that is causing the power to limit and not the battery temp as I'd been driving for well over half an hour.
The trips mentioned above were all in Normal (so the heating is at full) and it doesn't matter if I switch back and forth to eco or sport, the effect is the same. In fact it's like the button does nothing.
Assuming I had roughly 50% charge when I set off that would mean i have about the same capacity as my wifes 22kw Zoe. Its annoying as that hasn't ever had anything like this in the 6 years we've had it. Just frustrating that I have double the battery but in the winter only half of it is "useable" to it's full power. Means I now don't want the battery to dip below half. Not good as I have a 200 mile trip to do this Friday which will be fun....
Surely with 50 miles to go it should be nowhere near power saving mode? You'd think that would only need to kick in when the car is down to 10% (red light). As mentioned above, I got home and put it on charge at 36% which just seems unacceptable to me especially as the car doesn't tell you that its about to drop the power, you just find out when you try to accelerate.

 

[Tim Green]

I have never had any drop in available power whatever the battery charge.

 

[Cocijo]

Surely with 50 miles to go it should be nowhere near power saving mode? You'd think that would only need to kick in when the car is down to 10% (red light). As mentioned above, I got home and put it on charge at 36% which just seems unacceptable to me especially as the car doesn't tell you that its about to drop the power, you just find out when you try to accelerate.

A drop in power can be caused by an imbalance of cells in the HV battery pack. It’s done to protect them. I don’t know if you have balanced your pack recently but it‘s worth a try. It might improve low charge power.

 

[AK OK]

Hi, I'm just trying to work out if it's just me having some drop off in power availability with the gen 1 zs ev with this cold weather.
This morning (-5c) I set off on the school run with 50+ miles on the range and 4 bar showing on the battery. All seemed ok. Then I noticed after a mile or 2 that when accelerating it only peaked at 70% power. After dropping the first kid off I went on to drop the next off and the battery dropped to 3 bar and then I only had 60% power. After dropping the last kid off I cam home (around a 6 mile round trip) I noticed that the car would peak at 60% power and then drop to 50%. I got home and put the car on charge and it had 36% of the battery available!
I had this a week or so ago and found that if the first state of charge warning light came on I then had 40% peak power and would then drop off to 30% and the car could barely get to 50-55mph.
This time when I put it on charge I had 21% on the battery).
All this is happening on one trip and the car isn't being switched off in between. Just as the the charge drops off so does the power.
A bit worrying when I live in MK and need to pull out on to roads which are either 60/70mph in rush hour.
I get that cold weather can affect the battery but this seems more "pre-programmed" to happen at set states of charge and is linked to the external temp, rather than the actual temp of the battery, as I assume the battery would be a bit warmer towards the end of the journey?
My biggest grip is that there is now on screen warning to state that the power is being limited which would be very handy to know!
I do have the car booked in on 7th March to have this looked at and also to repair the drivers wing mirror which won't go back in when locked.
Just wanted to know if anyone else had something similar?
I believe the latest BMS is on the car from the last service (voltage dropped to 449 rather than the old 455?) and I can now charge on an AC without having to lock the car. Not sure if this has anything to do with it?
Thanks for any comments!

Didn't you chase this earlier this year ?

 

[SRMiller07]

Didn't you chase this earlier this year ?

Hi, I did have a post a while back (March I think) and work got hectic so never got to the garage. It then got to the point where it was due a service in Sept so mentioned it then. They did all the updates so had hoped the issue had gone away. Granted that was the summer so the issue didn't present itself again like it is now. I'm booked into the garage early march and just wanted to see if anyone else has had a similar issue in the cold.
It seems to me to be when it hits a certain battery %, below a certain air temp, it then reduces the power in 10% increments. i.e. -2c outside at 50-40% battery limit is 70% power, 40-30% battery is 60% power, 30-25% battery is 50% power, 25% and below its down to 40% power.
It's really odd as I would expect a loss of power when the battery is cold but then for the power to come back as you drive the car and it warms up? I could be massively wrong on this but that seems more logical to me.

A drop in power can be caused by an imbalance of cells in the HV battery pack. It’s done to protect them. I don’t know if you have balanced your pack recently but it‘s worth a try. It might improve low charge power.

Hi, I tend to charge the car at home and it usually gets left over night which I believe is a good way to balance the cells? That's on the 7kw charger, I haven't tried to do it with the 3 pin one to see if a slower charge helps?

I have never had any drop in available power whatever the battery charge.

Cheers for this. So with the cold weather (sub zero) and low charge, but before the orange light, you have not had it tail off the power?
I have a 70 plate 44kwh battery model.

 

[Lovemyev]

Hi, I tend to charge the car at home and it usually gets left over night which I believe is a good way to balance the cells? That's on the 7kw charger, I haven't tried to do it with the 3 pin one to see if a slower charge helps?

The A/C 7 Kw wall box or the Granny unit will balance in the same way, no difference.
It’s only D/C rapids that you can’t perform a balance with.

 

[SRMiller07]

The A/C 7 Kw wall box or the Granny unit will balance in the same way, no difference.
It’s only D/C rapids that you can’t perform a balance with.

Cheers, that was my understanding. I don't often charge on the rapids. I tend to pop it on charge at the local Tesco for little top ups, the first 15min is still free before you need to start the charge ;-) But do try and fully charge the car at least once a month and with the cold it's been weekly/fortnightly. The car only has a bit under 15k on it and that's since Sept 2020.

 

[Lovemyev]

Cheers, that was my understanding. I don't often charge on the rapids. I tend to pop it on charge at the local Tesco for little top ups, the first 15min is still free before you need to start the charge ;-) But do try and fully charge the car at least once a month and with the cold it's been weekly/fortnightly. The car only has a bit under 15k on it and that's since Sept 2020.

I know they say "every little helps" but charging in that short 15 minute slot, before the Pod point post stops charging, is hardly worth plugging in for TBH.

 

[AK OK]

I know they say "every little helps" but charging in that short 15 minute slot, before the Pod point post stops charging, is hardly worth plugging in for TBH.

45p ?

 

[SRMiller07]

I know they say "every little helps" but charging in that short 15 minute slot, before the Pod point post stops charging, is hardly worth plugging in for TBH.

ha, I know. if I'm in for a "big shop" I just tend to start it after 10min or so. It does work very well on our Zoe as that can use the 22kw chargers to its full. My wife doesn't do that many miles so can actually a good top up, almost 6kw, that last a few days.

45p ?

Nearly a meal deal on our Zoe

 

[AK OK]

ha, I know. if I'm in for a "big shop" I just tend to start it after 10min or so. It does work very well on our Zoe as that can use the 22kw chargers to its full. My wife doesn't do that many miles so can actually a good top up, almost 6kw, that last a few days.


Nearly a meal deal on our Zoe

22 X 0.25 = 5.5 X 30p = £1.65...

Nearly half a meal deal

 

[SRMiller07]

22 X 0.25 = 5.5 X 30p = £1.65...

Nearly half a meal deal

I remember when we could fully charge our Zoe for that

Back to the original post, I assume that the general agreement is that no one else has had the same issue with limited power in the sub zero temps. At least it seems to be an issue with my car then and something I can take up with MG when it's in in March. Unfortunately the weather will have picked up by then so will be a tough one to replicate the issue.
I'll try and remember to post any update just in case anyone else has anything similar.
Thanks again for the comments, much appreciated.

 

[MikeN]

Hi, If the car is fully charged then there is no drop off and all seems normal.
However I did a round trip to Oxford (about 80ish miles) and did notice on the final bit of the trip the power was dropping off to 70%. That was just before christmas and I can't remember the temp but it was cold out. This leads me to believe it's the air temp that is causing the power to limit and not the battery temp as I'd been driving for well over half an hour.
The trips mentioned above were all in Normal (so the heating is at full) and it doesn't matter if I switch back and forth to eco or sport, the effect is the same. In fact it's like the button does nothing.
Assuming I had roughly 50% charge when I set off that would mean i have about the same capacity as my wifes 22kw Zoe. Its annoying as that hasn't ever had anything like this in the 6 years we've had it. Just frustrating that I have double the battery but in the winter only half of it is "useable" to it's full power. Means I now don't want the battery to dip below half. Not good as I have a 200 mile trip to do this Friday which will be fun....
Surely with 50 miles to go it should be nowhere near power saving mode? You'd think that would only need to kick in when the car is down to 10% (red light). As mentioned above, I got home and put it on charge at 36% which just seems unacceptable to me especially as the car doesn't tell you that its about to drop the power, you just find out when you try to accelerate.

Hate to say, but after 6 years could your battery be knackered?

 

[Susanna]

@MikeN
I think the car is a 70 plate, so less than 3 years old.

 

[MikeN]

Hate to say, but after 6 years could your battery be knackered?

Sorry, thought your thread said 6 years

 

[Kithmo]

I know they say "every little helps" but charging in that short 15 minute slot, before the Pod point post stops charging, is hardly worth plugging in for TBH.

Saw a woman with a PHEV the other day at Tesco's pod point 7kW doing the old unplug and re-plug after the 15 minutes was up, without confirming the charge, to get another free 15 minutes.

 

[crite40]

I am a retired electronics engineer and I was very surprised by the owners surprise at having reduced range in very cold weather. It has always been my understanding that this was a characteristic of Lithium based batteries. Luckily I live in NZ where frosts are uncommon. But some way of warming the battery while in the garage would seem to be a good idea. I remember that Swedish IC engines used to have a little immersion heater to keep the oil and water from getting too cold.
Unfortunately electric cars are not the best yet in very cold climates. My ZSEV is still going very well after a year.

 

[SRMiller07]

Saw a woman with a PHEV the other day at Tesco's pod point 7kW doing the old unplug and re-plug after the 15 minutes was up, without confirming the charge, to get another free 15 minutes.

I can see why if they are going to sit in the car anyway, not like they have left it for ages after the free bit. We do our main shop in Lidl now (unfortunately ours don't have any chargers) and then nip into Tesco to get any odds and ends that we couldn't get so only in there for 10-15min so don't see the point in confirming the charge in the app. Granted it's only 1-2% but cancels out the trip.