Miles Guess O meter way out after service

[colEdinburgh]

2023 MG4 SE.

Had car for 12 months just went to in for first service. Software was updated during the service.

Problem i have is when I picked it up the battery was at 80% but only showing 89 miles.

Charged overnight. Battery 100% and miles showing ad 124.

I reset the accumulated miles. Should be getting about 220 miles but still showing 124.

Drove 10 mules and miles left dropped to 121.

So somethings out of sync. Is there anything I can do or do I have to go back to the dealer to fix?

 

[siteguru]

Which SE? SR or LR? (PS - please update the Driving item in your forum profile so as to avoid such questions in future).

 

[colEdinburgh]

SR

 

[Jomarkh]

They may have reset the trip counters which are used to calculated the GOM.
Did they note the SOH on the service report?

 

[colEdinburgh]

They ticked a box for battery check.

The car is 12 months old. It's done 3000 miles. The battery was working correctly before they updated the software

 

[colEdinburgh]

Soh ok

 

[Martinonline]

I think they may have corrupted the BMS so that it does not know the lower voltage for ~0% (min range) and that for 100% (max range). You will probably have to drive down the battery percentage to 10% and charge to 100% to reset the BMS, as per the manual. As you drive down the level you may find the miles you get per 1% is higher than normal or you seem not to lose any miles once your battery is in low percentages.

 

[siteguru]

Soh ok

They're supposed to write in the actual readings in those boxes

 

[Jomarkh]

They ticked a box for battery check.

The car is 12 months old. It's done 3000 miles. The battery was working correctly before they updated the software

That is poorly filled out ask them to put a percentage in.

 

[Rolfe]

The chances are the car just needs a bit of calibration, and to learn your driving habits again.

Drive it till it's below 10% charge (carefully for the last bit if you can't trust what the GOM is saying), let it sit there for a couple of hours, then charge it back up on an AC charger to 100% and let it balance, in one single charging session. That should fix it I think.

 

[colEdinburgh]

Battery drained to 5% Loss of power warnings started at 40% but stuck with it to 5%

Recharged to 100%. Reset the accumulated info.

No difference. Still showing 124 miles.

Booked in to MG