Battery capacity not match with consumption figures

[hojnikb]

Probably the best degradation indicator could be to reset the total trip and check the GOM at 100%. It resets to WLTP values, so your value/rated wlp should net somewhat accurate degradation.

 

[Cabansail]

I have done an exhaustive test on my MG 4 77 and find the usable battery capacity between a fully balanced full charge and an indication of 0% is consistently about 68 kWh which goes someway to explain the disappointing range compared with the claim figure. I have tried to claim under warranty and have been told the car is behaving normally. There are only two interpretations
1 the advertising is fraudulent and MG know that the actual battery capacity usable is 10% less than the claim or
2 my car has suffered premature battery degradation and they are trying to escape warranty responsibility

Before making these claims the testing method and equipment used needs to bedocumented. The measuring equipment must be calibrated at an international test house. This will give the accuracy and resolution of the equipment used.
Next the Test Method will need to be stated with records of the load applied and ambient temperature/humidity at the time. This will probably only be possible by using a calibrated dynamometer and using the standard loads stated in the standard being applied.

This is the process that all vehicle manufacturers must meet for compliance. Some manufacturers have tried to fake these tests. Famously VW were found out and the penalties were onerous along with their loss of reputation.

If you are relying on the car instruments and driving on the road then the results would not be reliable or have any legal standing.

I do hope you take this to court and come back to tell us the outcome. I could do with a good belly laugh.

 

[Evergreen]

Before making these claims the testing method and equipment used needs to bedocumented. The measuring equipment must be calibrated at an international test house. This will give the accuracy and resolution of the equipment used.
Next the Test Method will need to be stated with records of the load applied and ambient temperature/humidity at the time. This will probably only be possible by using a calibrated dynamometer and using the standard loads stated in the standard being applied.

This is the process that all vehicle manufacturers must meet for compliance. Some manufacturers have tried to fake these tests. Famously VW were found out and the penalties were onerous along with their loss of reputation.

If you are relying on the car instruments and driving on the road then the results would not be reliable or have any legal standing.

I do hope you take this to court and come back to tell us the outcome. I could do with a good belly laugh.

In theory I agree with you but

A dynamometer would measure the energy delivered at the wheels which does not directly relate to battery capacity as some of it is used other than by the driving motor

It is quite valid to use the car instrumentation although it does leave it open for MG to say their own instrumentation is inaccurate by more than 10%, which raises other interesting questions!

I have tried it under different ambient temperature conditions and it seems to make no difference and in any case the car is supposed to have battery management controlling the temperature

Like all storage batteries the capacity is indeed load dependent and I would claim that the only relevant load is what I use when I’m normally driving. I am going to try to run the test of using the entire battery capacity under low load by keeping the car in economy mode keeping my speed down and not using the heater or air-conditioning. If that does bring the calculation nearer to the manufacturer specification then the argument is whether the specification is realistic or not and whether they should include in their advertising that the battery capacity is quoted under ideal conditions just like the theoretical range

I will keep the forum posted unless of course somebody offers me some kind of generous confidentiality settlement prior to the matter going to court

I am only able to do this because here in New Zealand we have a small dispute court system which is very cheap , no lawyers are allowed, if you lose the other side can’t claim costs against you and if you win the other side can’t appeal to any higher court