MG5 won't balance charge (2020 pfl exclusive)

[Pebblefeline]

I only get

Roewe eRx5

Or is this the same?

 

[MickeySw]

On a this the same?

Don’t think so, it’s an SUV…

 

[Pebblefeline]

Suspected so

Ok so the profile is right the info is odd

Can anyone with car scanner look at the main dashboard screen and see what their CMU’s say?

Sigh

 

[Petriix]

Set to mg5 profile
It turns out they aren’t module s they are the Cell Monitoring Units that govern groups of cells
I believe the long range has 96 cells so in groups of 4 with a CMU in each? Giving 24 CMU’s?
These re reported by car scanner and each CMU reports in the cell voltage to the Bms I think.

Can anyone else with car scanner look at their CMU readings?

Now we are so far beyond my knowledge, I started reading a CMU research paper and ……. Well I got a headache

Yes, my CMU readings are 3.22V when fully charged.

 

[crispyjay]

As a rough calculation from 10% of actual size (rounded - 61kWh or should it be 57 usable ?) would need approx 55kWh (51kWh).
Onboard charger is 6.6kW so would require over 9 (8.5) hours plus balancing time to go 10-100%. - Just about a full at work
Can't remember if the 5 Trophy has 11kW charging, if so times obviously reduce a fair chunk.

All rough guesstimations.

Balance day! Didn’t leave until 5.15pm

 

[walter]

I did a few weeks ago on my 74 plate trophy 7% to 100% charge with a (7kW) home charger at a rate of 6.5kW it took 8 hours 58 minutes for 60.48kWg of energy including balancing.

 

[Gomev]

I did a few weeks ago on my 74 plate trophy 7% to 100% charge with a (7kW) home charger at a rate of 6.5kW it took 8 hours 58 minutes for 60.48kWg of energy including balancing.

Sounds about right if that's the power supplied. 93% added of 61kWh is about 57kWh or 93% of usable 57kWH is 53kWh.
Take away conversion losses from supplied 60.48 from that added and it could match using either usable or total capacity.

 

[MickeySw]

Sounds about right if that's the power supplied. 93% added of 61kWh is about 57kWh or 93% of usable 57kWH is 53kWh.
Take away conversion losses from supplied 60.48 from that added and it could match using either usable or total capacity.

You can only access/charge the ‘usable’ battery capacity.

 

[Gomev]

You can only access/charge the ‘usable’ battery capacity.

I don't think the buffers top and bottom are kept separate in different cells from the usable part, it is still a 61kWH battery pack, the whole of which gets charged and discharged, just the very top and very bottom isn't usable.

 

[MickeySw]

I don't think the buffers top and bottom are kept separate in different cells from the usable part, it is still a 61kWH battery pack, the whole of which gets charged and discharged, just the very top and very bottom isn't usable.

The theoretical capacity of a battery pack is derived from the maximum capacity of each cell, e.g. 150Ah from 2.5V-4.3V.

The BMS limits this voltage range (e.g 2.8V -4.1V) which will slightly decrease the overall capacity but greatly increase the longevity of the battery.

The top/bottom buffers can therefore not be accessed.

 

[Gomev]

The theoretical capacity of a battery pack is derived from the maximum capacity of each cell, i.e. 150Ah from 2.5V-4.3V.

The BMS limits this voltage range (e.g 2.8V -4.1V) which will slightly decrease the overall capacity but greatly increase the longevity of the battery.

The top/bottom buffers can therefore not be accessed.

Precisely, they are software buffers for the whole battery preventing overcharging and overdraining, not physical entities in their own right.
I think we are agreeing but terminology is getting in the way. The usable battery is as you describe restricted by the BMS from using the entirety of those cells capacities whereas your original comments inferred they were separate cells that were in effect held in reserve and never accessed or charged.

You can only access/charge the ‘usable’ battery capacity.