Test your MG4 battery to understand low range

[Evergreen]

I’m disappointed with the range of my MG4 77kWh and as an electrical engineer I’ve looked into the battery capacity, which is easily measurable. My initial findings are that it is far short of the claim, less than 70kWh. The MG agent has no credible explanation for this, and I’m commencing legal action for a refund of some of the purchase price.

 

[Martinonline]

Could you please expand on how you have measured the battery's capacity.

And can you please expand on how you use the car, eg lots of short journeys, mixture of short and long, long journeys only, car used every day, every other day etc.

[EDIT] Sorry , perhaps I should have said: ’How did you come to your conclusion that the battery was not as specified?'.

Thanks.

 

[HazardLights]

I’m disappointed with the range of my MG4 77kWh and as an electrical engineer I’ve looked into the battery capacity, which is easily measurable. My initial findings are that it is far short of the claim, less than 70kWh. The MG agent has no credible explanation for this, and I’m commencing legal action for a refund of some of the purchase price.

It started with a 74.4 kWh usable capacity, which reduces with battery aging. You can observe the current value with the car scanner app and an OBD dongle. I wouldn't rush to court.

 

[Evergreen]

Measu

Could you please expand on how you have measured the battery's capacity.

And can you please expand on how you use the car, eg lots of short journeys, mixture of short and long, long journeys only, car used every day, every other day etc.

[EDIT] Sorry , perhaps I should have said: ’How did you come to your conclusion that the battery was not as specified?'.

Thanks.

Very simple.
Fully charge
Zero the accumulated journey recorder
Drive till battery % is zero
Then you have used all the useable capacity as the car is no longer safely drivesble
The car displays distance covered and kWh per 100km (or maybe per 100 miles in some areas).
Multiply the two together and divide by 100 gives you the kWh you’ve used.
In my case it’s always around 67 whereas the spec is 77
Method and type of driving and weather etc does of course affect the estimated range but not the real capacity.
Try it yourself and if you find the same as me you have a very valid complaint, actionable in most legislations.

 

[Evergreen]

There’s a lot of talk about poor range on MG4.
Very hard to quantify as driving and weather have huge influence.
However kWh capacity is numerical and can be measured easily.
Mine is a 77kWh model and in reality is only 67, so I’m commencing legal action.

[ Moderator: Deleted redundant text that was apparently meant to be a self quote from the immediately prior post. ]

 

[Tuareg]

Not as simple as that at all. It all depends on how you drive the car, same with ICE vehicles and everyone will get a different result as they live in different places, differen climates, different topographies, different traffic volumes, more/less highways, different textures of road surfaces, different seasons, different temperatures etc, etc.......... and different drivers. It's the same as the question frequently asked about "how long" a specific tyre will last - depends on the same factors.

A manufacturer will point out exactly the same varying factors. Good luck with your legal action but it won't help you as the manufacturer will point out exactly the same real world circumstances as I have in the above text.

 

[Evergreen]

Not as simple as that at all. It all depends on how you drive the car, same with ICE vehicles and everyone will get a different result as they live in different places, differen climates, different topographies, different traffic volumes, more/less highways, different textures of road surfaces, different seasons, different temperatures etc, etc.......... and different drivers. It's the same as the question frequently asked about "how long" a specific tyre will last - depends on the same factors.

A manufacturer will point out exactly the same varying factors. Good luck with your legal action but it won't help you as the manufacturer will point out exactly the same real world circumstances as I have in the above text.

Of course, the distance the car will travel will vary according to driving and weather, you can tell that easily, mine can vary from about 7km per kWh on a good day, to under 5 when it's cold and raining hard.
However the capacity in kWh is absolute, and I have measured it as 15% below the manufacturers' claim, which is most definitely actionable in our (and probably most) legislations (and tends to support the general moan that the MG4 range is more out of touch with the claim than most EVs).

The ICE analogy is that it's hard to complain about the MPG or km/100 litres, but very easy to measure if the fuel tank is smaller than specified !

 

[DixieTGS]

My gut feeling is that the main reasons for the discrepancy you're seeing will due to the measurements and calculations done to provide the accumulated distance and accumulated kWh per 100km that you're using.

As a user, teasing apart how much error is in each figure could be quite challenging. Good luck.

 

[ReintjeWA]

I’m commencing legal action for a refund of some of the purchase price.

So you eat your meal but want a discount? If the meal is unsatisfactory you should send it back entirely. Asking for a discount might not be as successful as just rejecting the car entirely, but I know nothing of kiwi law and courts so maybe your approach is better.

 

[ReintjeWA]

What’s the SoH of the battery pack though? Are all cells at their optimum balance etc etc etc?

Also, the ER has a usable capacity of 74.4 kWh as listed by MG themselves

 

[Evergreen]

My gut feeling is that the main reasons for the discrepancy you're seeing will due to the measurements and calculations done to provide the accumulated distance and accumulated kWh per 100km that you're using.

As a user, teasing apart how much error is in each figure could be quite challenging. Good luck.

The calculation is high school physics!
The measurements are from the vehicle's own instrumentation. If MG want to claim that's no good, then....

So you eat your meal but want a discount? If the meal is unsatisfactory you should send it back entirely. Asking for a discount might not be as successful as just rejecting the car entirely, but I know nothing of kiwi law and courts so maybe your approach is better.

I like your analogy ! I guess that if, after eating a meal, I read the menu more carefully and found that it should have had say three meatballs, but in fact there were only two, i could ask for some money back!
If I had found this problem much sooner after buying the vehicle I might have tried for a complete refund, although that takes it to a higher and more expensive court
If I did it now, there would be arguments about the value of the use I've had of the vehicle
Our small disputes procedure here is very inexpensive, no chance of any other costs even if you lose, and if you win the other side cannot appeal to a higher court. It tends to be a customer focussed system and our Consumer Guarantees Act would allow a partial refund
I believe that you have similar legislation, but your small claims court system does give a right of appeal

What’s the SoH of the battery pack though? Are all cells at their optimum balance etc etc etc?

Also, the ER has a usable capacity of 74.4 kWh as listed by MG themselves

View attachment 40458

I know the claimed usable capacity is 74.4 and even the legality of calling the vehicle long range 77 could be challenged. Battery balanced regularly as per MG procedure. I am getting the SOH tested by a local very respected EV specialist. Not cheap as there's a lot more to it than a dongle and an app, which is a bit too rough and ready to use as evidence
Taking the figure of 74.4, mine is about 10% low
If this is a loss of SOH in one year, it is a warranty claim
If it's simply an untrue statement, then it's a misrepresentation of goods claim

 

[Bam Bam]

I’m disappointed with the range of my MG4 77kWh and as an electrical engineer I’ve looked into the battery capacity, which is easily measurable. My initial findings are that it is far short of the claim, less than 70kWh. The MG agent has no credible explanation for this, and I’m commencing legal action for a refund of some of the purchase price.

According to the EV database the usable capacity starts at 74.4 and will reduce from there with degradation.

MG MG4 Electric 77 kWh

All details and specs of the MG MG4 Electric 77 kWh (2023). Compare price, lease, real-world range and consumption of every electric vehicle.

ev-database.org

Some qusetions:

1. Are you claiming that all MG4 ERs have a smaller battery than claimed, or just yours?
2. Are you claiming you have fewer modules/cells than advertised or that the cells don't have as much capacity as advertised?
3. What does car scanner report as your battery capacity?
4. Have you used an independent testing company (like AVILOO) to confirm your battery status?

Your test methods:
You've said you are driving until the "battery % is zero" but can you be sure you really were at zero?

Furthermore, you should never take a lithium ion battery to zero as you would do it irrevocable damage. The car probably wouldn't let you.

Some people take EVs down as low as possible (in video tests like those of CarWOW and Bjorn Nyborg) but they recharge immediately so hopefully (for the future owners of those cars) it doesn't do any lasting damage if you don't leave it extremely low.

I'm sceptical that you will get anywhere with your claim against a large company unless you get a lot of other people to join you and get a lot more evidence.

 

[Evergreen]

According to the EV database the usable capacity starts at 74.4 and will reduce from there with degradation.

MG MG4 Electric 77 kWh

All details and specs of the MG MG4 Electric 77 kWh (2023). Compare price, lease, real-world range and consumption of every electric vehicle.

ev-database.org

Some qusetions:

1. Are you claiming that all MG4 ERs have a smaller battery than claimed, or just yours?
2. Are you claiming you have fewer modules/cells than advertised or that the cells don't have as much capacity as advertised?
3. What does car scanner report as your battery capacity?
4. Have you used an independent testing company (like AVILOO) to confirm your battery status?

Your test methods:
You've said you are driving until the "battery % is zero" but can you be sure you really were at zero?

Furthermore, you should never take a lithium ion battery to zero as you would do it irrevocable damage. The car probably wouldn't let you.

Some people take EVs down as low as possible (in video tests like those of CarWOW and Bjorn Nyborg) but they recharge immediately so hopefully (for the future owners of those cars) it doesn't do any lasting damage if you don't leave it extremely low.

I'm sceptical that you will get anywhere with your claim against a large company unless you get a lot of other people to join you and get a lot more evidence.

I think it is likely that all MG4 - 77s have smaller usable capacity than claimed but I only have to prove mine to win a case in the small disputes tribunal
Mine is 15% less than the model name suggests and 10% less than the small print claim
It really doesn't matter whether that's one year's degradation or a false advertising claim - either way it's unsatisfactory
As I am using the car's own instrumentation for the calculations and the indication of % state of charge from 100 to 0, MG can only argue that their instrumentation is wrong
When it's down to "0" I agree that I would hope that isn't really empty, but there are so many reasons not to drive the car beyond that, that it is realistically the end of the usable charge
I have no fear of taking on a giant company in our legal system. For claims under $30,000 there is no right to bring lawyers, no costs can be awarded and no appeal can be made against the findings. I've won against banks, government departments large manufacturers and landlords. The only time I lost (a case brought against me) the plaintiff was granted a payment from me of $4 per week for a claimed and disputed $4,000 debt.

 

[Tuareg]

According to the EV database the usable capacity starts at 74.4 and will reduce from there with degradation.

MG MG4 Electric 77 kWh

All details and specs of the MG MG4 Electric 77 kWh (2023). Compare price, lease, real-world range and consumption of every electric vehicle.

ev-database.org

Some qusetions:

1. Are you claiming that all MG4 ERs have a smaller battery than claimed, or just yours?
2. Are you claiming you have fewer modules/cells than advertised or that the cells don't have as much capacity as advertised?
3. What does car scanner report as your battery capacity?
4. Have you used an independent testing company (like AVILOO) to confirm your battery status?

Your test methods:
You've said you are driving until the "battery % is zero" but can you be sure you really were at zero?

Furthermore, you should never take a lithium ion battery to zero as you would do it irrevocable damage. The car probably wouldn't let you.

Some people take EVs down as low as possible (in video tests like those of CarWOW and Bjorn Nyborg) but they recharge immediately so hopefully (for the future owners of those cars) it doesn't do any lasting damage if you don't leave it extremely low.

I'm sceptical that you will get anywhere with your claim against a large company unless you get a lot of other people to join you and get a lot more evidence.

Yep, just like the German guy thinking he can sue MG regarding open source software that MG isn't 'releasing'. Some people always angling to become a 'peoples' hero when they are in fact completely deluded themselves for various other reasons.

 

[DixieTGS]

The calculation is high school physics!
The measurements are from the vehicle's own instrumentation. If MG want to claim that's no good, then....

I wasn't referring to your calculation.

The bit I think is problematic is mostly how MG calculate the energy used. If they work off the difference in battery voltage each time, they are measuring tiny differences in voltage which are prone to many different types of error e.g. the various hardware components and rounding errors. If they work off of the sum of current measurements over time, the same types of problems exist, and only some can be overcome by better hardware

In effect you will probably be having to prove multiple smaller faults rather than one large one.

Also you may want to look at how the battery capacity is specified in the manufacturer's datasheets. They quite likely measure the voltage at intervals with a fixed current output. If a particular use has a different current drain the measured capacity will be different to the specification.

 

[HazardLights]

I would recommend using the onboard diagnostics rather than approximation based on summary statistics. Moreover I suspect your method may ignore other battery drain such as air conditioning and in car entertainment which would introduce further inaccuracy. As a retired scientist, I would say your method is error prone.

 

[Kithmo]

I don't see the problem. If your car is one year old and lost 10% SOH then it's still within the specifications. The warranty only comes into effect when it's lost 30%.

 

[ReintjeWA]

If the method of calculating energy used is accurate, then surely it would also accurately calculate / predict the energy put back into the battery when charging from 0% to 100%?

 

[Chrisdriving]

Seriously?????
Thanks for explaining how to do a capacity test, been driving EV’s 10 years now and never figured that out.

 

[Martinonline]

@Evergreen, thank you for replying to my post, I now understand where you are coming from.

If I have understood you correctly, you are using the figures displayed by the car. So, do you know how those figures are calculated and what rounding actions are taken?

Please confirm that, for your calculations, you have completely charged and balanced the car and then driven continuously to zero charge with the car finally giving up.

I ask this because I have found that the miles/kWh figures only give an acceptable answer for single journeys. When I use the figure after carrying out many small journeys it gives a capacity figure well down from the specification of my Trophy LR.

Note I multiplied up from a 10% battery level drop for the matching mileage - on 3 occasions over the same route - to calculate the answer near to the battery specification.

Search for 'Battery level not match with consumption figures' in this forum for more discussion of this topic.