Troublesome figures

[Cirprocon]

Just completed a 106 mile round trip, mostly motorway at 50-55 mph, reached as high as 4.4 kWh and as low as 3.8 on the "current journey display". Had had a full charge the night before. Got back home with 13 miles left
119 is that all there is !
Even if I took an average of 4.0 Kwh I should reach more than the 160 miles quoted.

 

[Mark Holmes]

Just completed a 106 mile round trip, mostly motorway at 50-55 mph, reached as high as 4.4 kWh and as low as 3.8 on the "current journey display". Had had a full charge the night before. Got back home with 13 miles left
119 is that all there is !
Even if I took an average of 4.0 Kwh I should reach more than the 160 miles quoted.

When you battery is fully charged on the electrical information screen what voltage is your car showing with everything switched off?
I’m asking incase you have the bad BMS....

 

[Cirprocon]

Thanks for asking Mark, I can confirm I had a BMS update last year and I was initially concerned it was the bad one after others had complained of seeing reduced range. I phoned my dealership and they said I had not received the bad update, I even emailed Miles from the podcast and he also confirmed with my VIN number that according to MG records I did not receive the bad BMS. As to the question of overall pack voltage after a slow charge I have seen figures from 437 volts to 445 volts but more towards the lower end with recent charges. The post above was my acid test to prove that driving economically should have seen me reach more then what I eventually got. Its just worrying that according to MG records mine didn't receive the bad update.

 

[Mark Holmes]

Thanks for asking Mark, I can confirm I had a BMS update last year and I was initially concerned it was the bad one after others had complained of seeing reduced range. I phoned my dealership and they said I had not received the bad update, I even emailed Miles from the podcast and he also confirmed with my VIN number that according to MG records I did not receive the bad BMS. As to the question of overall pack voltage after a slow charge I have seen figures from 437 volts to 445 volts but more towards the lower end with recent charges. The post above was my acid test to prove that driving economically should have seen me reach more then what I eventually got. Its just worrying that according to MG records mine didn't receive the bad update.

Your voltage still seems very low as it should be at least 449 volts on a full charge, are you allowing the equalisation process to take place with each full charge on the granny charger or 7 KW home unit; if you have one as it appears the cells still need to be balanced from your voltage figures..

 

[Cirprocon]

Just unplugged after last nights home charge on the 7kW, voltage is reading 436 volts. This would have included the long balance charge until the logo goes out. I agree Mark it does seem low and appears to be getting worse. The conundrum I have is that my dealer and Miles appear to agree that mine hasn't had the bad BMS according to MG. All I can offer the dealership is real world figures that I achieve, I wonder if there is a log kept within the ECU of miles/kWh and distance covered that the dealership can access for fault finding. The maths just don't add up at the moment.

 

[Mark Holmes]

Just unplugged after last nights home charge on the 7kW, voltage is reading 436 volts. This would have included the long balance charge until the logo goes out. I agree Mark it does seem low and appears to be getting worse. The conundrum I have is that my dealer and Miles appear to agree that mine hasn't had the bad BMS according to MG. All I can offer the dealership is real world figures that I achieve, I wonder if there is a log kept within the ECU of miles/kWh and distance covered that the dealership can access for fault finding. The maths just don't add up at the moment.

I would suggest that you may have the bad BMS and that it will continue to get worse unless corrected, do you have another MG dealer local to you that you can get for a 2nd opinion? You are about 14 volts off where you should be with the newest BMS of 449 volts

 

[Cirprocon]

Thanks Mark, I will contact them tomorrow.

 

[Mark Holmes]

Thanks Mark, I will contact them tomorrow.

Also point to note from the original BMS you are even further from the top as the upper and lower buffer zones were adjusted on the last corrected update, prior to that the upper limit on volts was around 455 volts.

 

[Jake]

I would suggest that you may have the bad BMS and that it will continue to get worse unless corrected, do you have another MG dealer local to you that you can get for a 2nd opinion? You are about 14 volts off where you should be with the newest BMS of 449 volts

Or perhaps a defective battery pack? If the dealer/Miles are adamant about the BMS what else? It will be useful to find out the reason when Cirprocon contacts the dealer.

 

[Mark Holmes]

Thanks Mark, I will contact them tomorrow.

Please let us know what the outcome is, good luck

 

[Lovemyev]

Daft question :-
Has your car had the Comfort 2 update done by any chance ?.
Depending WHEN it was done has identified as another route that the car could have been infected by a software glitch.
When the VIN number is checked, this may not identify your car as one recorded by the system ?.
My guess is the dealer will update the car to the very latest software on its next visit regardless !.
Their computer will show just what software you are running on anyway !.
MG Tech will advise that the software should be updated firstly.
This then should see you getting figures of around 448 - 450 volts after a full charge & balance and a range of around 160 - 162 miles on the GOM with all items turned off.
This will be in the default setting of driving mode NORMAL and Regen level 3.
The dealer may tell you that a number of home charges will be necessary to rebalance the pack over a number of weeks.
Therefore, you may not see the figures quoted above straight away.
They should also be able to tell you what the level of imbalance IS on the HV pack.
Good luck .

 

[Cirprocon]

Great, thanks for the advice. I will update you all when I speak to the dealership.

 

[Sean]

Mine was not on the faulty BMS list but my dealer did some diagnostics, emailed China with the results, who confirmed I needed the JAN BMS update

 

[Cirprocon]

For info mine did have the Comfort 2 update but it was done pre-delivery. Sean that's interesting that your dealer confirmed you needed the Jan BMS update. I spoke with dealership and mentioned the ever decreasing battery voltage (now 436 volts). I will report back as I was also told like Sean that mine was not given the faulty BMS update according to MG.

 

[Dr Dave]

I think you should invest in an OBD2 dongle and check what the actual BMS software is on your vehicle. You think you do not have the faulty BMS according to MG. The dealer should be able to check the exact BMS with their diagnostic. I decided to check the actual BMS myself with a dongle, I can also check cell voltage differences.

 

[Cirprocon]

Hello, just picked up the car this morning. Dealership have given my car the latest BMS update. I now have to balance charge most evenings to get back to 449 volts from my current 436 volts. It appears as though I was indeed given the bad BMS back in October 2020. This is very disappointing !! I was assured by the dealership first time around that according to MG records mine was the correct BMS.
PLEASE everybody if you are in doubt and your range and overall voltage is low after a charge book it in straight away.

 

[Mark Holmes]

Hello, just picked up the car this morning. Dealership have given my car the latest BMS update. I now have to balance charge most evenings to get back to 449 volts from my current 436 volts. It appears as though I was indeed given the bad BMS back in October 2020. This is very disappointing !! I was assured by the dealership first time around that according to MG records mine was the correct BMS.
PLEASE everybody if you are in doubt and your range and overall voltage is low after a charge book it in straight away.

Well done, fingers crossed for you that your voltage climbs…

 

[Dr Dave]

436v is far too low. Return the car to the dealer and ask them to rebalance until 449v is reached. This is what I did after all it was MG who installed the bad BMS they need to take responsibility and properly fix the problem. Hope the attached helps.

 

[DrTom]

I have only had my EV a couple of weeks but I just find the whole GOM thing a lottery. Turn car on one time, 70 miles range next time 50 miles, after only doing a couple of miles. Charged with granny charger and got the recommended 449V. Just got my home charger yesterday, charged last night and have voltage of 455V. Assured by dealership when picked up the car that it has all the latest software updates. No wonder they call it a guessometer. Will never trust it to give anything like an accurate range until they sort out the software.

 

[Cirprocon]

It seems to be a bit of a lottery, dealers don't seem that confident with what they are told.