MG ZS ev mk1 2020 battery pack voltage

[Gstathers]

Good afternoon all, new to the forum. Apologies if this has been covered but can't find it.
I recently bought a MG ZS ev 2020.
One thing I have noticed is the voltage reading on the main battery pack is around 431v. I have been reading this should be around the 450v mark. I will carry out a full balance to see if this rectifys it. But my question is have other people experienced this voltage drop after a full charge and what rectifys the issue?
Many thanks in advance

 

[dragon2611]

It will be lower depending on the state of charge, it's perfectly normal.

I think in most cars the cells are nominally 3.7v each but can be as high as 4.1v when fully charged.

 

[Jomarkh]

Can you confirm with MG if all the BMS updates have been done as this was a real issue for early ZS models.

 

[Gstathers]

Can you confirm with MG if all the BMS updates have been done as this was a real issue for early ZS models.

Thank you for the reply. I have sent the dealer the software version we have and awaiting reply. Also had a "please slow charge the vehicle" when I left work today. Will update once I hear back from the dealer

Can you confirm with MG if all the BMS updates have been done as this was a real issue for early ZS models.

Checking with the dealer today and just awaiting reply

 

[mystreet]

Thank you for the reply. I have sent the dealer the software version we have and awaiting reply. Also had a "please slow charge the vehicle" when I left work today. Will update once I hear back from the dealer

Sounds like that the battery balancing has not been done at all. If that's the case, expect a long time to get the battery back to good health.
Let it balance, go for a 20 mile drive then balance again.

 

[Gstathers]

Sounds like that the battery balancing has not been done at all. If that's the case, expect a long time to get the battery back to good health.
Let it balance, go for a 20 mile drive then balance again.

Will let it do a full balance, trip to work then do another full balance. Like you said don't think it's ever been done.

 

[Jomarkh]

There was a guy it may have been @Dave S that spent months balancing his battery after the early updates.

 

[Gstathers]

There was a guy it may have been @Dave S that spent months balancing his battery after the early updates.

I hope I don't have the same issue with months of balancing

 

[Lovemyev]

Do a quick search in the forum under the title of BMS Updates.
It will provide a deep and extensive thread on Gen1 models running in different software models.
It will provide a long history of cars that were affected by the introduction of buggy software on certain updates.
This affected the cars badly, with regards to predicted range and even loss in power.
Not all cars were affected of course.
In this thread you will find info that spells out what HV pack voltages and range predictions you SHOULD expect to see, depending on what version of software your car is running with.
It also gives info on battery balancing and how long this should take, depending on any imbalance in the pack, or which software version you are running !.
It’s very informative, but a long and interesting read.
Way too much info to compress into answering the question on this thread !.
Very quick answer :- Original factory software, around 455 - 456 volts and after BMS update 448 - 450 volts if my memory serves me correctly.
So, it may suggests that you HV battery is in urgent need of a balance cycle from a A/C supply ASAP.

 

[Gstathers]

After a full charge and balance over night the attached picture was the outcome. Looks like we have an older BMS and that millage is very low. Thoughts would be much appreciated?

Edit, heating was on, jumped to 141 miles once off but still low right, will do another balance tonight.

 

[N2STY]

Thoughts would be much appreciated?

And you reset both trip counters?

 

[ARealHuman]

You will need to be in eco mode to get anything like the promised range (163 miles) on the display. As I'm sure you know, when charging, the pulsing MG logo on the front of the car will go out when the battery is balanced, but will stay lit when fully charged.

 

[Gstathers]

And you reset both trip counters?

Yes both trip computers reset

 

[Lovemyev]

Yes both trip computers reset

In your photo above, it is displaying 130 miles recorded by one of the trip meters ?.
Before you commence a charge, reset BOTH trip counters.
Ensure that you have turned OFF all 12 volt items, especially the HVAC controls.
Then charge the car to 100% remembering NOT to remove the charging lead.
The balance cycle only commences AFTER the car has reached 100%.
Depending on the level of imbalance in your pack, it could take a number of hours to achieve a balanced state.
It wii only attempt to balance for about 8 hours, if it does not effectively achieve it in this time frame, it will give up until the next time.
If you have a home energy meter, you can plot the cycle on that.
Are you using a wall box or a Granny lead ?.
When the car has completed the balance, then boot up the car into the default ready mode.
Now scroll through your info screen and check the predicted range on the GOM and the voltage on the pack.
I would keep a written note of your what you are witnessing or take a photo on your phone.
Then you will be able to plot any increase on the figures you are getting.

 

[Gstathers]

Thank you for that, I am using a granny charger In the garage wall socket (awaiting home charger install pod point)
I will try another charge and balance tonight ensuring all 12v items are switched off and reset both meters before hand. Is it worth disconnecting the 12v battery on the negative at some point to reset all previous owner usage? (does this wipe any installed firmware/software

 

[Lovemyev]

No need to carry out a 12 volt disconnect, there is no real gain TBH.
Save your 10mm use for another day .
Purely an assumption on my part here, but given the age of your car and the small mileage it has covered, I would suspect the car has been used for short trips and then put on charge for a few hours.
It is possible that it has never received any ( or only a few ) proper balance cycles.
If you keep a photo dated record of your charging & balancing habits, it will be easy to monitor any improvements in the predicted range.
In the worst case, you then have documented evidence IF you need to seek help or advice from a dealer.
Remember, you MAY need to carry out a number of balance cycles IF your pack is badly imbalanced.
Some members have invested in a OBD port reader, that can be used to interrogate the cells in the battery and produce a SOH check report.
A quick search above will bring up suggestions of types suitable for your car.
I am sure somebody will read this post and advise on this subject.

 

[Gstathers]

No need to carry out a 12 volt disconnect, there is no real gain TBH.
Save your 10mm use for another day .
Purely an assumption on my part here, but given the age of your car and the small mileage it has covered, I would suspect the car has been used for short trips and then put on charge for a few hours.
It is possible that it has never received any ( or only a few ) proper balance cycles.
If you keep a photo dated record of your charging & balancing habits, it will be easy to monitor any improvements in the predicted range.
In the worst case, you then have documented evidence IF you need to seek help or advice from a dealer.
Remember, you MAY need to carry out a number of balance cycles IF your pack is badly imbalanced.
Some members have invested in a OBD port reader, that can be used to interrogate the cells in the battery and produce a SOH check report.
A quick search above will bring up suggestions of types suitable for your car.
I am sure somebody will read this post and advise on this subject.

Thank you for advise, very much appreciated. I would agree looks like used for short journeys with, in my opinion battery never looked after. Good suggestion I will document SOC etc.. I have already ordered an ODB2 reader so I can check the battery stats, firmware, software....

 

[JCFlippen]

Thank you for the reply. I have sent the dealer the software version we have and awaiting reply. Also had a "please slow charge the vehicle" when I left work today. Will update once I hear back from the dealer


Checking with the dealer today and just awaiting reply

Don’t forget software on the infotainment system is nothing to do with ECU software.

 

[Gstathers]

Finished work today, checked what I believe is BCM build number (picture attached), reset all trips, ensured all 12v loads off and currently (pardon the pun) on slow charge using the granny charger. Will leave it to 100% and balance. Will report back shortly. With hopefully improved range after a full charge etc.....

 

[Gstathers]

Seeing improvements now after many a balance been carried out. Seeing around 150 miles on the "guess oh meter" on normal and about 162 on eco. Thank you to all those who chipped in for advice, I t is very much appreciated