Battery capacity

[Chrissunray]

@Chrissunray
I think you car definitely needs to go back to the garage.
You are right. It seems the whole of the battery is not being utilized.
It is more likely a software problem from a misapplied update but may also be a battery pack problem. There is no way of excluding a battery pack problem yourself so my advice will be to send it in.
One problem is that when you go to the dealerships your problem is recorded by a service clerk/receptionist. You will need to make sure that what the clerk has written is exactly what you want to tell the technician. Infact ask the clerk to call the technician so you can tell the tech yourself if possible. With EVs, these clerks are still learning and often what the these clerks write is far removed from what the actual problem is.

Thanks for that. I’ve sent an email to the garage so hopefully get the car booked in and get it looked at properly. Fingers crossed

 

[JodyS21]

I am confused.

After a full charge my battery shows 439v and a displayed 169 miles of range in 'N'. I had comfort 2 carried out in December but I think I need the latest (15-01-2021) BMS update to get to 450v.

When I had the updates carried out in December my range dropped to a poor 125 miles in 'N' after a full charge. I recently reset the m/kWh cumulative and per trip and this increased the range to 169 miles at full charge.

My car goes in for service next week but I am unsure if I should request the latest BMS update as the range is back to 160+ miles, were it was when I bought the car, with pre comfort 2/BMS update.

Any advice?

If you are only getting 439V fully charged & balanced, then you definitely have the problem BMS and you need to get it fixed by the dealer ASAP before it gets even worse and takes even longer to get back to full health.

 

[JodyS21]

@Dr Dave
From the little that you have written, I will say confidently that there is absolutely nothing wrong with your car.
I know a lot has been written about this update in regards to voltage, upper and lower buffers, GOM etc but the truth of the matter is that unless you are someone who drives till the GOM shows zero before you top up then there will be absolutely no effect on your actual driving range from this update. On paper it is good to have in that it makes more battery available but unless you get it done at a dealership who know what they are doing you may end up with more trouble than any practical benefit.
Also the change in your GOM numbers may actually have had nothing to do with the GOM reset as such. Could explain further but main thing is that your car is absolutely OK going by what you have written.

The car is definitely not ok.
Until it is fixed the battery will get in a worse state.
The worse state it is in, the longer it will take to get back to it's proper state.

This is all very well documented on the forums and in the pod cast.

 

[JodyS21]

@JodyS21
You are right in the comments you have made except that the GOM actually uses only data for the last 10 to 20 miles (in some cars even less). This is because statistically it data is deem closer and more predictive for the current conditions you are driving in than what your accumulated data from last summer would show. The GOM self updates every 30sec to 1min so that is why when the weather is cold the GOM starts to show lower numbers and in the summer the numbers improve.

Ah, maybe we're talking about slightly different things.
When you first start the car and it gives you the GOM then this I believe is based on the Accumulated Trip data (since it was last reset).
Once you've been driving a bit, it knows what type of driving you're then doing and as you say gives an guess based on what you're actually doing

 

[JodyS21]

Story so far. BMS update done in Nov, we all know what happened then. It has now been 10 days since my recent 2021 BMS update. Voltage has reduced from 456v down to 450v, Range has dropped 30mls on GOM on a full charge, car still will not do a delayed charge on Smart Charger although Charger will work normally with doors unlocked. Numerous charges have been done everyday since update although battery charge has really never dropped below 70%. I have been leaving the charger on all night to make sure the car balance charges. I am finding that when I go to disconnect the Charger the following day the charger lock disengages and within about 3 sec it re engages the lock and starts a balance charge again? I can only assume the battery is still trying to rebalance itself since the update. Anyway will contact Dealer tomorrow to see what they intend doing regarding the delayed charging issue. By the way just to check it was not my Smart Charger that was causing the issue I had my Son inLaws car here this weekend doing numerous delayed charges on his car each one working as it should so there is no doubt it is the MG that is causing the issue and not the Charger.

It is not unheard of that one of the updates hasn't been applied correctly, a very similar thing had been reported by someone else.
The dealer needs to go through the system and update what's been missing/mis-configured. They may need to send the cars data through to MG tech support.

 

[KasEV]

Ah, maybe we're talking about slightly different things.
When you first start the car and it gives you the GOM then this I believe is based on the Accumulated Trip data (since it was last reset).
Once you've been driving a bit, it knows what type of driving you're then doing and as you say gives an guess based on what you're actually doing

@JodyS21
Hi, well people get very confused about this but the purpose of the accumulated data is solely to give an idea of cumulative fuel efficiency. It does not contribute to the mileage that is displayed in the GOM not at the beginning, middle or end of your journey. In fact even some of the EV tech do not get how GOM work correctly and wrongily say it uses the cumulative data to avoid trying to give the correct explanation. Each time you start the car only the last 10 to 20 miles/ 10 to 20mins of the journey you where doing before the stop is used to calculate the distance the GOM will display. As you continue to drive along it will recalculate every 30sec to 1min or 1 to 2 miles and keep updating itself. That is how it works. So if you had a very warm yesterday and parked the car overnight, the GOM may show 163 miles when you start it today morning because it is using data from yesterday's last 20miles when the weather was warmer to calculate. Now because of the severe frost this morning as soon as you have driven 5-10mins the GOM number will drop down as the GOM self updates to you current conditions. So now GOM may show 140 miles. Then those who do not understand will say my GOM is not working properly because I drove only 6miles but it has dropped from 163 to 140. Along the way if the sun comes up today as well and the weather becomes warmer it will self update again with better readings so now you make another 5miles in this warmer weather and now the GOM shows138 miles and people then get all confused that the GOMs are not accurate. Well if you truly understand how GOM works you will realise how clever the design is.
The current GOMs are designed to as the question if conditions remain similar to what they have been in the last 10 min/10 miles how far will this car travel with the current SOC of the battery.
They are designed to just take some cumulative data that may not reflect current conditions and use it to predict what will happen in current conditions. Anyway I hope you have a small grasp of how the current GOM works it is a dynamic system based on current data not cumulative data.
People like to think that if the GOM shows 100miles at the beginning of a journey then come what may one should be able to travel 100miles be it summer. Winter Autumn Rainy or Snow. Unfortunately the current GOMs are not designed that way.
I believe Tesla may be in the process of developing a fixed mileage GOM that runs down form a fixed value per distance traveled for their very high mileage vehicles. The problem with this type of GOM is they grossly underestimate mileage in vehicles with small batteries as they are based on worse case scenario data and based on 90 to 95% of the battery. If one puts such a GOM in a 44 kWh car the GOM will may never show more than 100 to 120 miles in eco mode.

 

[KasEV]

The car is definitely not ok.
Until it is fixed the battery will get in a worse state.
The worse state it is in, the longer it will take to get back to it's proper state.

This is all very well documented on the forums and in the pod cast.

@JodyS21
How did you come to the conclusion that @Dr Dave car is not OK.
One should go by the information that Dr Dave has given rather than hearsay. In the information that Dr Dave has given he does not say he has had the faulty BMS update and he clearly states his car is charging normally to show 163 miles at a reasonable voltage so how did you conclude that there is something wrong with @Dr Dave car. I may have misunderstood something so please do correct me.

 

[JodyS21]

@JodyS21
Hi, well people get very confused about this but the purpose of the accumulated data is solely to give an idea of cumulative fuel efficiency. It does not contribute to the mileage that is displayed in the GOM not at the beginning, middle or end of your journey. In fact even some of the EV tech do not get how GOM work correctly and wrongily say it uses the cumulative data to avoid trying to give the correct explanation. Each time you start the car only the last 10 to 20 miles/ 10 to 20mins of the journey you where doing before the stop is used to calculate the distance the GOM will display. As you continue to drive along it will recalculate every 30sec to 1min or 1 to 2 miles and keep updating itself. That is how it works. So if you had a very warm yesterday and parked the car overnight, the GOM may show 163 miles when you start it today morning because it is using data from yesterday's last 20miles when the weather was warmer to calculate. Now because of the severe frost this morning as soon as you have driven 5-10mins the GOM number will drop down as the GOM self updates to you current conditions. So now GOM may show 140 miles. Then those who do not understand will say my GOM is not working properly because I drove only 6miles but it has dropped from 163 to 140. Along the way if the sun comes up today as well and the weather becomes warmer it will self update again with better readings so now you make another 5miles in this warmer weather and now the GOM shows138 miles and people then get all confused that the GOMs are not accurate. Well if you truly understand how GOM works you will realise how clever the design is.
The current GOMs are designed to as the question if conditions remain similar to what they have been in the last 10 min/10 miles how far will this car travel with the current SOC of the battery.
They are designed to just take some cumulative data that may not reflect current conditions and use it to predict what will happen in current conditions. Anyway I hope you have a small grasp of how the current GOM works it is a dynamic system based on current data not cumulative data.
People like to think that if the GOM shows 100miles at the beginning of a journey then come what may one should be able to travel 100miles be it summer. Winter Autumn Rainy or Snow. Unfortunately the current GOMs are not designed that way.
I believe Tesla may be in the process of developing a fixed mileage GOM that runs down form a fixed value per distance traveled for their very high mileage vehicles. The problem with this type of GOM is they grossly underestimate mileage in vehicles with small batteries as they are based on worse case scenario data and based on 90 to 95% of the battery. If one puts such a GOM in a 44 kWh car the GOM will may never show more than 100 to 120 miles in eco mode.

Very interesting.
Obviously I have no actual knowledge of how MG have programmed the GOM in the ZS EV. Would be fascinating to see what they have actually used for their algorithm.

What I do know is that when the Accumulated Trip is reset, it resets the GOM calculation, therefore it is logical to assume that its algorithm is based partly on what data is in the accumulated trip.

One thing is for sure, the GOM algorithm in the ZS EV is not at all very accurate. I personally believe based on everything else MG have done, they have not put much effort into making it very clever and that it is using a pretty basic calculation.
Quick example of how bad it is, today. Everything reset before starting off changed the GOM to be 182miles. After 52 miles driving to work, GOM says 102 miles. There is no way 102miles is correct based on what it's current driving profile is. After coming home later the GOM will be about 30 miles.

 

[KasEV]

Very interesting.
Obviously I have no actual knowledge of how MG have programmed the GOM in the ZS EV. Would be fascinating to see what they have actually used for their algorithm.

What I do know is that when the Accumulated Trip is reset, it resets the GOM calculation, therefore it is logical to assume that its algorithm is based partly on what data is in the accumulated trip.

One thing is for sure, the GOM algorithm in the ZS EV is not at all very accurate. I personally believe based on everything else MG have done, they have not put much effort into making it very clever and that it is using a pretty basic calculation.
Quick example of how bad it is, today. Everything reset before starting off changed the GOM to be 182miles. After 52 miles driving to work, GOM says 102 miles. There is no way 102miles is correct based on what it's current driving profile is. After coming home later the GOM will be about 30 miles.

OK, I can not explain what is happening with your specific GOM just based on one set of data. The information I have given is in general for most of the current GOMs on the market. A few brands have a few modifications but among people who work in the industry it is said that the ZS EV GOM is one of the most accurate.

 

[JodyS21]

@JodyS21
How did you come to the conclusion that @Dr Dave car is not OK.
One should go by the information that Dr Dave has given rather than hearsay. In the information that Dr Dave has given he does not say he has had the faulty BMS update and he clearly states his car is charging normally to show 163 miles at a reasonable voltage so how did you conclude that there is something wrong with @Dr Dave car. I may have misunderstood something so please do correct me.

It's pretty obvious from reading everything that is on the forum (and from podcast) and has been stated repeatedly.

A car with pre 15/1/2021 BMS, when fully charged, a healthy balanced battery pack is at/near 455Volts.
A car with 15/1/2021 BMS, when fully charged, a healthy balanced battery pack is at/near 450Volts.

"After a full charge my battery shows 439v and a displayed 169 miles of range in 'N'. I had comfort 2 carried out in December but I think I need the latest (15-01-2021) BMS update to get to 450v."

@Dr Dave 's car fully charged (and balanced) now only shows 439V.
He hasn't had the 15/1 BMS installed as his car was at dealer in December.
The range is kind of irrelevant in determining/identifying if it has the bad BMS.
His battery cells are way out of balance, hence it will only charge to a total of 439V out of normal 455V.
The dealer must have installed the dodgy October BMS when it was in.

I can't remember the exact figure that people have found, but after having the 15/1 fix applied, it takes something like 10 hours of balancing to recover each 1 volt.
This would mean after having the fix applied, it's going to take something like 110 hours of balancing to get his battery back to full health.
The longer it is left and the car used/battery cycled, the worse/lower the voltage will end up and the longer it will take to get it back to full health.

 

[JodyS21]

OK, I can not explain what is happening with your specific GOM just based on one set of data. The information I have given is in general for most of the current GOMs on the market. A few brands have a few modifications but among people who work in the industry it is said that the ZS EV GOM is one of the most accurate.

I'm pretty sure, everyones GOM is working the same, several people have said, when they reset the accumulated it "resets" the GOM.

The way the GOM should work in an ideal world is indeed basically as you have described.
Each manufacturer surely comes up with the own data and process for calculating it, they're not going to share that IP knowledge - it'd be worth a lot of money. MG are clearly not as technologically advanced as someone like Tesla, which is why their GOM (amongst other things) isn't great.

Do you find that the GOM is quite accurate in your car and for your normal driving?
Most people on here think it's pretty rubbish and what it says is rather untrustworthy. I've found it to be almost a waste of time unfortunately.

 

[AussiePete]

No, after the latest update, it charges to 4.16v per cell to reduce stress on the battery, so total voltage is now 449v/450v. If you're still showing 455v, you need the latest update.

Paulie, I probably do as I’m still getting 455v and I picked up car in December. However given all the chatter on the BMS issues I may hold off until things stabilise as I don’t thing my BMS is the dodgy one

 

[Paulie68]

Paulie, I probably do as I’m still getting 455v and I picked up car in December. However given all the chatter on the BMS issues I may hold off until things stabilise as I don’t thing my BMS is the dodgy one

My BMS was the old one too, with no issues, the January 15th release has caused no problems for me, just lowered the top voltage. You will get this release as the faulty one has been withdrawn.

 

[jamesie]

Paulie, I probably do as I’m still getting 455v and I picked up car in December. However given all the chatter on the BMS issues I may hold off until things stabilise as I don’t thing my BMS is the dodgy one

I'm in the same boat Pete. Picked up my car on 25 Nov and it charges to 456v. The BMS update is a service action so the dealers will likely not do the update outside of that unless it's paid. Also, you're right to watch proceedings with the new BMS as MG haven't covered themselves in glory with previous releases.

 

[mj224]

Must add that on my little Citroen Zero, the GOM was always spot on. Though it only had 50 miles to play with...

Unless you used loads of heat or A/C...

My ZS at full charge is less than 440 volts, and is going for an update this Wednesday..

 

[KasEV]

I'm pretty sure, everyones GOM is working the same, several people have said, when they reset the accumulated it "resets" the GOM.

The way the GOM should work in an ideal world is indeed basically as you have described.
Each manufacturer surely comes up with the own data and process for calculating it, they're not going to share that IP knowledge - it'd be worth a lot of money. MG are clearly not as technologically advanced as someone like Tesla, which is why their GOM (amongst other things) isn't great.

Do you find that the GOM is quite accurate in your car and for your normal driving?
Most people on here think it's pretty rubbish and what it says is rather untrustworthy. I've found it to be almost a waste of time unfortunately.

My GOM is absolutely accurate because I understand exactly what it should show and it shows exactly that. The problem is people think the GOM should show something else and have all sort of made up theories about the GOM so for such people the GOM is always wrong and unfortunately they find it hard to accept that it is their theories about the GOM that is wrong.
Regarding how good the MgZSEV GOM is, I believe it was better than Tesla's in 2019/2020 in terms of accuracy. Not everything about the MG is poor quality.

 

[KasEV]

It's pretty obvious from reading everything that is on the forum (and from podcast) and has been stated repeatedly.

A car with pre 15/1/2021 BMS, when fully charged, a healthy balanced battery pack is at/near 455Volts.
A car with 15/1/2021 BMS, when fully charged, a healthy balanced battery pack is at/near 450Volts.

"After a full charge my battery shows 439v and a displayed 169 miles of range in 'N'. I had comfort 2 carried out in December but I think I need the latest (15-01-2021) BMS update to get to 450v."

@Dr Dave 's car fully charged (and balanced) now only shows 439V.
He hasn't had the 15/1 BMS installed as his car was at dealer in December.
The range is kind of irrelevant in determining/identifying if it has the bad BMS.
His battery cells are way out of balance, hence it will only charge to a total of 439V out of normal 455V.
The dealer must have installed the dodgy October BMS when it was in.

I can't remember the exact figure that people have found, but after having the 15/1 fix applied, it takes something like 10 hours of balancing to recover each 1 volt.
This would mean after having the fix applied, it's going to take something like 110 hours of balancing to get his battery back to full health.
The longer it is left and the car used/battery cycled, the worse/lower the voltage will end up and the longer it will take to get it back to full health.

Very interesting.
Sounds likely a lot of hearsay than what Dr Dave has actually said about his car.
His car has not had the faulty update.
So why will he suddenly have a problem which is due to this faulty update?
439V will be about 125-127miles in the original settings so the most likely explanation of the figures Dr Dave gave is a delayed reset or other very simple explanations rather than assuming that @Dr Dave somehow has developed a problem that occurs with a particular software update that he clearly has told us has not been applied to his car.

 

[JodyS21]

Very interesting.
Sounds likely a lot of hearsay than what Dr Dave has actually said about his car.
His car has not had the faulty update.
So why will he suddenly have a problem which is due to this faulty update?
439V will be about 125-127miles in the original settings so the most likely explanation of the figures Dr Dave gave is a delayed reset or other very simple explanations rather than assuming that @Dr Dave somehow has developed a problem that occurs with a particular software update that he clearly has told us has not been applied to his car.

To be honest I can't be bothered with this anymore.
His car has the faulty BMS, it is obvious to anyone who reads & knows what is going on with the cars and voltages etc.

Enjoy your MG ZS EV experience.

 

[JodyS21]

My GOM is absolutely accurate because I understand exactly what it should show and it shows exactly that. The problem is people think the GOM should show something else and have all sort of made up theories about the GOM so for such people the GOM is always wrong and unfortunately they find it hard to accept that it is their theories about the GOM that is wrong.
Regarding how good the MgZSEV GOM is, I believe it was better than Tesla's in 2019/2020 in terms of accuracy. Not everything about the MG is poor quality.

I'm very happy for you that the GOM in your car is clever enough to guess what driving you're going to do next and show you an accurate figure.

I will continue to not trust & go by the GOM in my actual car (which does the same long journey 3 days a week) otherwise my wife will be stuck at the side of the motorway regularly with a flat battery.

Enjoy your MG ZS EV experience.

 

[Chrissunray]

That’s the car booked in for a few days to be checked over in April so fingers crossed they’re able to sort the battery. In the interim, I’ll keep up with the equalisations and hopefully see an improvement in the voltage / battery capacity. Thanks again to everyone for all the advice given - it’s much appreciated.