Sorry BMS again!

[JodyS21]

I cannot get my head around what version my pre reg Feb 2021 Zs EV should have? I was assured by the dealer that it had the latest software update when bought it in early June 2021. I have just discovered that my battery when fully charged at home has a voltage of 456v is this the version I should be on? I have not bought an OBD2 reader as do not have a working android device to see what versions of all software I have in place.

Personally, I would want the new bms version and ALL other updates, I would be a very unhappy chappy to be told this by your dealer and find out it is not true.
It really annoys me that still some dealers are basically incompetent, given the issues it's caused they have no excuse not to know by now how to check, arghhhh.

You could say well it's ok so just leave it, but there must be a reason for the change.
Perhaps more importantly, you could well have the dodgy version of the bms installed or the previous slightly buggy version. Until you've used the car for some time the voltage wouldn't potentially start dropping.

Given what the dealer has said, can you trust that it has got all of the other updates that there's been installed too?

 

[Saima]

Thanks for asking this question @JCFlippen.
And at risk of disclosing my utter lack of knowledge about all things batteries and volts, if I'm charging the car and the battery is at about 58%, the dash shows 410 volts, it that normal? Have I understood it correctly that it would show 456 or 449 only when fully charged?
Also it shows current as -8 amps, that normal too?
I had a go at charging on one of the street chargers, just to see how it would work. My plan is to now find a rapid charger and try that next!
Thanks in advance

 

[JodyS21]

Thanks for asking this question @JCFlippen.
And at risk of disclosing my utter lack of knowledge about all things batteries and volts, if I'm charging the car and the battery is at about 58%, the dash shows 410 volts, it that normal? Have I understood it correctly that it would show 456 or 449 only when fully charged?
Also it shows current as -8 amps, that normal too?
I had a go at charging on one of the street chargers, just to see how it would work. My plan is to now find a rapid charger and try that next!
Thanks in advance

The voltage drops as the battery capacity drops, perfectly normal.
All that matters regarding the voltage is what it shows after a full AC charge.

The Amps will totally depend how much load the car/battery is under.
When checking voltages etc, start the car without pressing the brake pedal, this way the High Voltage battery is not engaged and cannot be put under any load (by air con etc etc) when checking.

Have a go at starting the car fully (in ready mode), then watch the Amps when sitting stationary trying various things like air con on/off, heating on a little bit/then a lot etc. You'll see the Amps change.

 

[Adi6phil]

180+ miles between charges! How low do you run it?

I charge it up probably once a week .Is that what you meant cocijo?

 

[Cocijo]

I charge it up probably once a week .Is that what you meant cocijo?

I think I must have misunderstood. I thought you obtained 180miles range between charges. I’ve never seen that. Best I did was 145miles and battery was very low!

 

[Lovemyev]

Have we established yet if MG are updating all bms to 450v? I understood that all cars when next in for work would get this. The update is also supposed to further improve battery longevity. It seems some get it when their car is in and others don’t.

Apparently, all cars running on the OEM original software, SHOULD have their software upgraded to the latest BMS software when they are presented for their annual service.
However as we have seen, this is clearly NOT happening.
Either some dealers are not following the MG protocol and therefore carrying out the service bulletins, or they just choose to ignore them altogether !.
They just don't want the headache if something goes wrong.
We have received confirmation ( Miles Roberts ) that all cars leaving the factory and arriving here about now, are running on the 450 Volts BMS update.
New cars normally take about 3 months to get here !.

 

[Saima]

The voltage drops as the battery capacity drops, perfectly normal.
All that matters regarding the voltage is what it shows after a full AC charge.

The Amps will totally depend how much load the car/battery is under.
When checking voltages etc, start the car without pressing the brake pedal, this way the High Voltage battery is not engaged and cannot be put under any load (by air con etc etc) when checking.

Have a go at starting the car fully (in ready mode), then watch the Amps when sitting stationary trying various things like air con on/off, heating on a little bit/then a lot etc. You'll see the Amps change.

Thank you so much, that is really super helpful

 

[Lovemyev]

Have I understood it correctly that it would show 456 or 449 only when fully charged?

Correct, after a full charge & balance you SHOULD see either :-
456 Volts ( Original OEM software ) or 449 Volts ( After latest BMS update released 15th Jan 21 ).

 

[Cocijo]

It’s worth mentioning. I’ve never seen 456v. Mine is always 455v. I’ve heard of some getting as high as 458v. The same with the 450v it may vary by a volt or two. This is assuming all fully balanced of course and no faulty software! I think Jody has a good point - is it possible to have the bad bms but because you very rarely rapid charge and balance regularly you don’t notice and the pack stays stable?

 

[Adi6phil]

I think I must have misunderstood. I thought you obtained 180miles range between charges. I’ve never seen that. Best I did was 145miles and battery was very low!

I do get 180 ish between charges .eg i put it on charge today after doing 156 miles in eco with occasional ac on and miles remaining showed 27 .the amber light came on mid thirties i pushed my luck once cos i was on target for 190 but chickened out in mid 180s with red light on. Just checked and the car is fully charged and showing 154 in normal and 179 in eco with all trip meters zero'd prior to charging as i always do .next july i am going on holiday and the sat nav says 183 .you can guess whats going thro my mind

 

[Adi6phil]

It’s worth mentioning. I’ve never seen 456v. Mine is always 455v. I’ve heard of some getting as high as 458v. The same with the 450v it may vary by a volt or two. This is assuming all fully balanced of course and no faulty software! I think Jody has a good point - is it possible to have the bad bms but because you very rarely rapid charge and balance regularly you don’t notice and the pack stays stable?

I have had 457 once but usually 456

 

[Cocijo]

I do get 180 ish between charges .eg i put it on charge today after doing 156 miles in eco with occasional ac on and miles remaining showed 27 .the amber light came on mid thirties i pushed my luck once cos i was on target for 190 but chickened out in mid 180s with red light on. Just checked and the car is fully charged and showing 154 in normal and 179 in eco with all trip meters zero'd prior to charging as i always do .next july i am going on holiday and the sat nav says 183 .you can guess whats going thro my mind

Go for it!

 

[Adi6phil]

I do get 180 ish between charges .eg i put it on charge today after doing 156 miles in eco with occasional ac on and miles remaining showed 27 .the amber light came on mid thirties i pushed my luck once cos i was on target for 190 but chickened out in mid 180s with red light on. Just checked and the car is fully charged and showing 154 in normal and 179 in eco with all trip meters zero'd prior to charging as i always do .next july i am going on holiday and the sat nav says 183 .you can guess whats going thro my mind

Just a thought i have had my car 9 months from new and in that time i have never rapid charged it only ever have max 7kw and most times i charge it i leave it to fully equalise ,maybe i have a happy battery because of this, and therefore good range

 

[Lovemyev]

Go for it!

Yeah .
Go for it indeed my friend !.
Wow ..... respect, that is putting a LOT of faith in that GOM prediction alright.
Remember, it say's Typhoo on the sides of a buses, but they don't sell tea ! .
183 miles ......... "Like A Boss".

 

[jamesie]

I'm on the 456v OEM BMS.

I charged and fully balanced using my Zappi yesterday evening and kept a close eye on the power being used at each stage.

Up to 98% power was 6.5 to 7.0 kw.
98% to 100% power was 2.5kw.
At this point the balance commenced.
13 minutes at 2.5kw.
4 minutes at 2.0kw
Then complete, showing 456 volts.

I have read in a number of threads that on the latest BMS the balance runs at 300w and takes hours to complete.

Is this another reason to stay with the 456v BMS OR a reason to move to the latest?

Scratches head!!!

 

[rbpasapera]

I'm on the 456v OEM BMS.

I charged and fully balanced using my Zappi yesterday evening and kept a close eye on the power being used at each stage.

Up to 98% power was 6.5 to 7.0 kw.
98% to 100% power was 2.5kw.
At this point the balance commenced.
13 minutes at 2.5kw.
4 minutes at 2.0kw
Then complete, showing 456 volts.

I have read in a number of threads that on the latest BMS the balance runs at 300w and takes hours to complete.

Is this another reason to stay with the 456v BMS OR a reason to move to the latest?

Scratches head!!!

Mine has been balanced at 300-ish W before and after latest BMS update, but charging curve changed after update.

Before:

After:

 

[JCFlippen]

Have we established yet if MG are updating all bms to 450v? I understood that all cars when next in for work would get this. The update is also supposed to further improve battery longevity. It seems some get it when their car is in and others don’t.

I love my ZS EV (456v. BSM and assured by my dealer that I had the latest software when I bought it in early June 2021) but it is hard to dispel the notion that MG UK is run in a cheapskate/shambolic way regarding updates and the dissemination of technical information about common issues to all service departments. There does not seem to be a consistent MG face that brings confidence and enthusiasm to the brand in the same way Toddington does for Gridserve. Miles shows by example representing Chorley Group. These are exciting times and MG have good well priced EV products to shout about.

 

[Coulomb]

The voltage drops as the battery capacity drops, perfectly normal.

I think you should say as the battery state of charge drops, or at least as the battery remaining capacity drops. It's too easy to confuse state of charge and state of health, when both are expressed as a percentage.

 

[Gomev]

....- is it possible to have the bad bms but because you very rarely rapid charge and balance regularly you don’t notice and the pack stays stable?

No. With the bad BMS it did not balance even tho' it pretended to with the MG badge glowing.

 

[Lovemyev]

Is this another reason to stay with the 456v BMS OR a reason to move to the latest?

I can confirm that the balancing process “Post” BMS update DOES actually take longer than”Pre” BMS update, for sure.
My own theory ( correct or not ) on this subject, is because after the latest software has been applied, the charging curve has been adjusted and the buffer at the upper limit of the battery capacity has been increased.
This has can be clearer felt when driving the car “Post” update, as the Regen feels more linear and is available even when the battery reports that it is 100% fully charged.
For the Regen strength to be increased, then surely the space / capacity at the upper end of pack has been increased to allow for energy to be stored ?.
In regards to you question :-
“Is this a reason to stay with 456 volt BMS”.
It should not be an option really.
If the dealer network was to follow the instruction via the MG service bulletins, then each car ( when presented for annual service ) SHOULD get the update as a matter of course.
Would I be requesting the update ?.
Well, given the issues surrounding some dealers ability to get this update applied correctly, then I would think long and hard.
If the cars not broken, then why try and fix it !.
My car had the OEM software and was 199% fine, after a problem at the dealership at the time of the first service, it was promised dead and needed the latest BMS update as part of the fix.
Under the direct instruction of the MG Tech team.
The dealer was under there control, because they had completely run out of ideas on how to restore the car !.
So, having the decision to have the BMS update applied or NOT.
Was clearly outside of my control.
The dealer told me latter, that they generally ONLY apply updates under direct instruction from the MG Tech team, or by direct customer request.
This policy appears to be the standard for MOST dealers.
A “Don’t ask, don’t get policy”.
It makes perfect sense to me to have ALL ZS EV’s running on a standardised software package, but in actual fact, I can’t see this happening really.
If you report a problem with your car, then it is likely that the software will be brought up to date.
This will be the first thing that the dealer will be TOLD to do by MG.
It is the most cost effective option.
They will NOT be permitted to start firing the parts cannon at ANY car, until any software problems have been ruled out first !.
This is standard procedure with any manufacturer.
When contacting MG Tech with regards to eating help with a customers car, the first question will be this :-
“Has the car received ALL of the latest software updates available, if not, apply them first and THEN we will talk again”.
Common sense to most people you would think ?.