MG4 Battery Health

[jamakr4]

Mine has 99% at 10k km - 2023 Luxury (64kwh) Facelift (with rear wiper)

 

[Tig170]

LFP SE - Sept 22 model - from car scanner (but verified at service each year via UKMG) - no issues todate (aside from minor reduction in power @ <20% SOC at 70mph+)

... at this rate, the MG4 might see me out

 

[jamakr4]

LFP SE - Sept 22 model - from car scanner (but verified at service each year via UKMG) - no issues todate (aside from minor reduction in power @ <20% SOC at 70mph+)

... at this rate, the MG4 might see me out

View attachment 41008

For the NMC Battery it seems to be around 1% every 10k km. It's what I have experienced and if you watch reviews from other drivers it matches quite well with their SOH.

I have my next service appointment September next year and I will break the 20k km barrier till then. So if I remember I will post an update if the SOH is 98% or less.

 

[redwood98]

Mine has 99% at 10k km - 2023 Luxury (64kwh) Facelift (with rear wiper)

Mine (same model/year as yours) is 99.2% at like 8500km so about the same as yours

 

[Chrisdriving]

Interesting to see how X power battery ages as it has to deliver twice the power of the RWD, 320kW i believe so almost 6c discharge peaks.

 

[jamakr4]

Maybe this explains the amount of degradation some of you are experiencing:


So if you have your estimate via an OBD reader, you may want to do a “calibration charge” and measure again afterward to get more accurate numbers.
Drive the battery down until it’s almost empty, then charge it all the way up and measure again.

 

[tsedge]

SOH numbers don't really mean anything. There's no way to "measure" SOH.

Fill it full and see what range you get on a standard route in the same weather. Much better indicator.

 

[hojnikb]

SOH numbers don't really mean anything. There's no way to "measure" SOH.

Fill it full and see what range you get on a standard route in the same weather. Much better indicator.

Of course you can measure SOH. Very accuratly at that.

Top charge to 100%+balance and then discharge to empty empty (BMS cuts off due to low voltage). The resulting discharged energy is your actual pack capacity. Actual pack capacity divided by nominal new pack = SOH in %.

And BMS can calculate this internally. It has to, otherwise GOM would get progressively
less accurate (and optimistic) as battery degrades. So it needs to know actual energy content of the battery to calculate distance till empty.

 

[tsedge]

Of course you can measure SOH. Very accuratly at that.

Top charge to 100%+balance and then discharge to empty empty (BMS cuts off due to low voltage). The resulting discharged energy is your actual pack capacity. Actual pack capacity divided by nominal new pack = SOH in %.

And BMS can calculate this internally. It has to, otherwise GOM would get progresivly less accurate (and optimistic) as battery degrades.

Good luck getting an energy readout from the car, such calculations don't include all the losses. Yes you can do this with external equipment but hardly practical for most owners.

And what are you comparing it to? You'd need a baseline. Then, what would actually matter? - a noticeable drop in real world range.

Besides the thing being discussed here is the SOH readout from the dealer / OBD2 port, which is known to be a mixture of age-based algorithms and usage and an estimate. Different makes calculate this differently and there's no standard for it. You might be told your car is 98% but it is the real range that matters - dealers don't run the car from full to empty to measure anything.

The car either has enough range or it doesn't, it either has a noticeable decline or it doesn't, worrying about SOH percentages may be an interesting pastime but it isn't a necessary part of the ownership proposition.

 

[hojnikb]

Good luck getting an energy readout from the car, such calculations don't include all the losses. Yes you can do this with external equipment but hardly practical for most owners.

And what are you comparing it to? You'd need a baseline. Then, what would actually matter? - a noticeable drop in real world range.

Besides the thing being discussed here is the SOH readout from the dealer / OBD2 port, which is known to be a mixture of age-based algorithms and usage and an estimate. Different makes calculate this differently and there's no standard for it. You might be told your car is 98% but it is the real range that matters - dealers don't run the car from full to empty to measure anything.

The car either has enough range or it doesn't, it either has a noticeable decline or it doesn't, worrying about SOH percentages may be an interesting pastime but it isn't a necessary part of the ownership proposition.

As a driver you can fully charge the car + balance. And when the car is fully charged, immediatly go for a drive and run the battery completly. Resulting milage and consumption (along with energy spent on that trip) will give you a very nice indication on the actual energy battery has.

 

[tsedge]

As a driver you can fully charge the car + balance. And when the car is fully charged, immediatly go for a drive and run the battery completly. Resulting milage and consumption (along with energy spent on that trip) will give you a very nice indication on the actual energy battery has.

You mean run until the battery is empty? That's a bit of a time consuming exercise, including carrying an emergency charger, because getting to zero percent can have 20-30 miles left before the MG4 abruptly cuts out (the end is not very progressive).

And what is more relevant at the end of of that? Your energy use or the mileage you got?

Much easier just to pick a longer journey you normally do without charging and see if the car can still comfortably do it, without worrying if the remaining range is exactly the same.

Because SOH doesn't really matter, the only thing that does is "does the car still have enough range for me?".

 

[hojnikb]

You mean run until the battery is empty? That's a bit of a time consuming exercise, including carrying an emergency charger, because getting to zero percent can have 20-30 miles left before the MG4 abruptly cuts out (the end is not very progressive).

And what is more relevant at the end of of that? Your energy use or the mileage you got?

Much easier just to pick a longer journey you normally do without charging and see if the car can still comfortably do it, without worrying if the remaining range is exactly the same.

Because SOH doesn't really matter, the only thing that does is "does the car still have enough range for me?".

Both datas are relevant, because you can easily calculate available full charge energy of the battery. And thus calculate real SOH.

The problem with picking a longer journy is that there is just way way too much variables at play to say if the battery is still the same or not. You might do that journy one day, but not the other. By knowing energy content, you know what consumption you need to get to your destination.


I did the same test, just for fun. One was in dry sunny day, no AC, about 25C. Try to do 85-95km/h behind trucks. The resulting consumption was 102Wh/km.

The second test was in colder tempartures (14-16C) and rain. No heat or AC. Same speed and route as above. Consumption was 118Wh/km. So almost 20% difference just because of a few degrees lower temp and rain on the road.

That's why you can't do tests like this consistenly.

 

[tsedge]

I think you're missing my point, so I won't labour it.

Enjoy your SOH tests, all these measurements do seem to give people new interests to follow.

I'll continue to drive happily without knowledge of my SOH, knowing and trusting my car's range.

 

[LenEV2016]

Both datas are relevant, because you can easily calculate available full charge energy of the battery. And thus calculate real SOH.

The problem with picking a longer journy is that there is just way way too much variables at play to say if the battery is still the same or not. You might do that journy one day, but not the other. By knowing energy content, you know what consumption you need to get to your destination.


I did the same test, just for fun. One was in dry sunny day, no AC, about 25C. Try to do 85-95km/h behind trucks. The resulting consumption was 102Wh/km.

The second test was in colder tempartures (14-16C) and rain. No heat or AC. Same speed and route as above. Consumption was 118Wh/km. So almost 20% difference just because of a few degrees lower temp and rain on the road.

That's why you can't do tests like this consistenly.

It's interesting if that is your thing.

At the end of the day for me, and I'm sure a good few other.members, it's just a car. I drive it as I did my ice car I drive at the speed limits when possible, I use heat and AC when I need it. I fuel it when I need it. And as long as it continues to get me where Im going to I'm not overly fussed with anything else.i enjoy EVs for their relaxing drive and instant power on the accelerator.

All this driving with no heating or going 50,55,60mph on motorways isn't for me.
I actually think purposefully driving 10-15 mph under the speed limit is a massive pain in the preverbial and can cause issues for other road users but each to their own

 

[hojnikb]

It's interesting if that is your thing.

At the end of the day for me, and I'm sure a good few other.members, it's just a car. I drive it as I did my ice car I drive at the speed limits when possible, I use heat and AC when I need it. I fuel it when I need it. And as long as it continues to get me where Im going to I'm not overly fussed with anything else.i enjoy EVs for their relaxing drive and instant power on the accelerator.

All this driving with no heating or going 50,55,6mph on motorways isn't for me.
I actually think purposefully driving 10-15 mph under the speed limit is a massive pain in the preverbial and can cause issues for other road users but each to their own

This is just to remove as much variables as possible. In real life, you just don't drive like that, as it's a pain obviously.

 

[LenEV2016]

This is just to remove as much variables as possible. In real life, you just don't drive like that, as it's a pain obviously.

Didn't mean you do but there are a quite a large group of EV owners that do.
I always feel that all they accomplish is to just give ammunition to the anti EV mob that bang on about EVs being no good for long journeys

 

[hojnikb]

Didn't mean you do but there are a quite a large group of EV owners that do.
I always feel that all they accomplish is to just give ammunition to the anti EV mob that bang on about EVs being no good for long journeys

I'd still say, that driving just like the rest of trucks isn't a bad thing though. As long as you stick to that and don't drive slow when there's no trucks or on the passing lane.

But yeah, not a good image for EVs for sure.

 

[Chrisdriving]

Does SOH also not factor in IR, and ability to deliver power ie several factors regarding it’s condition and not just actual capacity?

 

[hojnikb]

Does SOH also not factor in IR, and ability to deliver power ie several factors regarding it’s condition and not just actual capacity?

State of health does affect that, but under normal driving conditions, you're not gonna be power limited until the battery is severly degraded.

 

[OriginalBigAl]

You mean run until the battery is empty? That's a bit of a time consuming exercise, including carrying an emergency charger, because getting to zero percent can have 20-30 miles left before the MG4 abruptly cuts out (the end is not very progressive).

And what is more relevant at the end of of that? Your energy use or the mileage you got?

Much easier just to pick a longer journey you normally do without charging and see if the car can still comfortably do it, without worrying if the remaining range is exactly the same.

Because SOH doesn't really matter, the only thing that does is "does the car still have enough range for me?".

I think that knowing your SOH is interesting and have been trying ( as a lot have ) to work out its value mathematically from the data we have readily available. My last set of data , and depending on how you compute them in different formats came up with , 91%...95%...97% interesting but about as much use as a chocolate fireguard.
The only time the question becomes important is if ( as Tom says ) if you have a drastic loss of unexplained range within the 7 year period and need to claim for a new battery.
You do your calculations , use an OBD reader find it on or below 70% , take it to a dealer/workshop , they use a different OBD reader or other specialized dealer only equipment , which gives a different figure , you accept/reject that figure and start a complaint. An independent qualified technician is called in , and comes up with a third figure. With MGs reputation , you can see where this is going!
Most present owners will most likely never reach either of those two limits ( 7 years / 70% ) so its going to be a question for 2nd hand owners down the line.....unless of course .... when trading in , the dealer puts on his own ( doctored ) OBD reader and says " Oh ! sorry mate, yer battery is down a lot on its SOH and I am going to have to reduce its value "