Inconsistencies promised WLTP range

[Kithmo]

Did anyone ever get the advertised mpg from an ICE car ? Especially VWs, so hardly surprising we don't get advertised range.

I did (and better sometimes) if I went on a long journey on warm day using A roads (no motorways) and driving at or below speed limits in light traffic. Exactly the same with the ZS on the one trip to the seaside, in between lockdowns last Summer, 4.5 m/kWh.

 

[Peter WA]

You have said EXACTLY what my "concern" is.
I want to see official WLTP testing figures based on what is our definite USABLE battery capacity is.

I got in contact with my dealer a few days ago. Since my primary contact is the salesman I asked him to please get the technical people involved.

First attempt to explain observations, by the local service department at that dealer, was to suggest that there is some 'reserve' capacity, like in a petrol tank, so stop people from running out. Admittedly I have never tried to drive below 0 range (my car doesn't show range any more once it drops to 15kms, not sure if other software versions do?). But from the OBD2 readings I know that that would at most explain the 4% at the bottom, not the 6% never charged at the top.

I asked to get the manufacturer involved to explain those 6%. Reply was along the line of needing to keep some reserve for KERS. Where would the energy go if the battery was full and someone wanted to use KERS? Yep, total disregard for basic physics, that KERS can only recover what first was drawn from the battery seems to have eluded the person who replied.

Aftersales support, still a sales person one assumes, not an engineer. I somehow don't think it is likely they keep battery capacity reserved for people who fully charge at the top of a mountain, then want to use KERS to over-charge the battery on the way down.

Next I asked quite exactly those questions you posed: what is the actual usable energy of the battery, and what efficiency (before losses) in kWh/100km was used to calculate the WLTP range of 263km for that usable capacity? No reply yet. I gave them time to ask China if no one here in Australia knows the answers. I'll keep pushing and prodding next week.

I think it is quite likely that the WLTP range was calculated based on the full 44.5kWh, and at some point later someone decided it would be prudent to limit the charge to 4 - 94% to improve battery life and reduce warranty claims, resulting in a reduced usable battery capacity to 40kWh.

It is entirely possible that initially it was an oversight that the range was never adjusted down to reflect that. Burt by now they must be aware of it and probably try to get out of it as cheaply as possible. The upgraded Indian model springs to mind.

I might start another thread and ask people to collect evidence for the actual battery size. I believe the easiest way would be if people who DC charge from quite a low state to almost full record battery % shown by the car at start and finish of charging and kWh shown by the charger.

With the benefit of hindsight I wish I'd kept better photo evidence of my charging sessions. The ones I have all work out to be about 40kWh battery size.

 

[TassiedEVil]

I believe VW quote the usable battery size on their ID3.

They probably learnt their lesson re truth in advertising over that other little ‘matter’ re emissions

 

[TassiedEVil]

View attachment 2037

This is a snippet from the Australian ZS EV brochure, download from the website just now.

Can anyone spot the inconsistency?

Ok here we go: 18.6 × 2.63 = 48.918. That means, for the WLTP range to be realistic with the given WLTP efficiency, our battery would need to have a usable capacity of 49kWh. Not a stated capacity of 44.5kWh and an actual usable capacity of 40kWh.

Irrespective of how the actually achievable range is affected by speed, temperature, wind, driving style, this shows that we are fighting a losing battle.

The question I have: any plausible explanation? Or simply fraud with the stated WLTP range?

Perhaps that number should be 215 km, which would match the actual real world experience of so many of us. Maybe it's not that the WLTP test is an unrealistic lab test, never seen in real life. Maybe MG just fudged some numbers? If they did, I believe in Australia at least, given our strong consumer laws, they'd be in a lot of trouble.

Oh, btw: I am a little over halfway in a 4500km road trip that tests the vehicle to the max. In perfect conditions, moderate temperatures and no wind or tailwinds, no elevation changes, I only manage to get close to the WLTP (and GOM) range if I drop my speed to a low 85km/h. Battery appears healthy, minimal difference between lowest and highest cell voltage.

Sounds like a great trip - and it seems to be giving you plenty of data to help work out what is going on with the WLTP range. This is a very interesting discussion! Safe travels Peter WA

 

[JodyS21]

I got in contact with my dealer a few days ago. Since my primary contact is the salesman I asked him to please get the technical people involved.

First attempt to explain observations, by the local service department at that dealer, was to suggest that there is some 'reserve' capacity, like in a petrol tank, so stop people from running out. Admittedly I have never tried to drive below 0 range (my car doesn't show range any more once it drops to 15kms, not sure if other software versions do?). But from the OBD2 readings I know that that would at most explain the 4% at the bottom, not the 6% never charged at the top.

I asked to get the manufacturer involved to explain those 6%. Reply was along the line of needing to keep some reserve for KERS. Where would the energy go if the battery was full and someone wanted to use KERS? Yep, total disregard for basic physics, that KERS can only recover what first was drawn from the battery seems to have eluded the person who replied.

Aftersales support, still a sales person one assumes, not an engineer. I somehow don't think it is likely they keep battery capacity reserved for people who fully charge at the top of a mountain, then want to use KERS to over-charge the battery on the way down.

Next I asked quite exactly those questions you posed: what is the actual usable energy of the battery, and what efficiency (before losses) in kWh/100km was used to calculate the WLTP range of 263km for that usable capacity? No reply yet. I gave them time to ask China if no one here in Australia knows the answers. I'll keep pushing and prodding next week.

I think it is quite likely that the WLTP range was calculated based on the full 44.5kWh, and at some point later someone decided it would be prudent to limit the charge to 4 - 94% to improve battery life and reduce warranty claims, resulting in a reduced usable battery capacity to 40kWh.

It is entirely possible that initially it was an oversight that the range was never adjusted down to reflect that. Burt by now they must be aware of it and probably try to get out of it as cheaply as possible. The upgraded Indian model springs to mind.

I might start another thread and ask people to collect evidence for the actual battery size. I believe the easiest way would be if people who DC charge from quite a low state to almost full record battery % shown by the car at start and finish of charging and kWh shown by the charger.

With the benefit of hindsight I wish I'd kept better photo evidence of my charging sessions. The ones I have all work out to be about 40kWh battery size.

I will follow this with a great deal of interest.
I should officially pose the same question to MG UK really.

It is very difficult for us to get exact proof.

If you could do a flat to full charge via DC, it should indeed show it without the conversion losses, can you actually do a complete full charge via DC though?

Re the WLTP tests, from the very complicated detailed information I found, I do not know if when they charge the car back up following the test to calculate the power required to refill it - if that includes doing a balance or if they use the basic stop once it's "charged" point.

I'm still stuck using a granny charger for a few more weeks until I get a proper AC home charger, at that point I should be able to get actual figures for how much power is used to fully charge the car. Need to do yet another run-flat and then charge test to get those figures.

 

[Graham King]

Yes, it's a waste of energy, but in a way comparable to how ICE engines only convert say 30% of the energy from fuel into motion. Another way EVs are a lot better, lower losses. Of course if electricity is made from fossil fuels, a similar waste occurs on the way from fossil to electricity.

I'll reply in more detail when I get home. An 2016 article I found was about a (then) new way of having only 3% conversion losses AC to DC, as opposed to a more typical higher value, they quoted 6% I believe. A lot lower than 10%, which would include the charging losses too. Those 3% are in line with what modern solar inverters achieve in the other direction, from DC to AC.

As to actual kWh charged: my OpenEVSE does document those for each charging session. The problem I have here on the road is that only the current is measured, the voltage is taken to be standard grid voltage. (Which is weird, since voltage is so much easier to measure than current)

Crossing the Nullarbor ymuch of that electricity comes from diesel generators. Putting strain on only one phase of the 3-phase supply will see voltage drops. If I assume that I charge on 230V after those drops rather than the 240V the grid is supposed to have, then the actual usable capacity using an AC charger, before losses, comes to about 44kWh.

Even if those generators were able to supply a steady 240V on one heavily loaded phase, that would only be 46kWh. Both figures well short of the 49 we should see on AC to charge a 44.5kWh DC rated battery.

I will have accurate voltage readings and therefore accurate kWh once I can charge back at my own home (more accurate at least, some losses still occur in the wires between my solar inverter and the car charger). If I was a betting man I'd put money on finding the same result.

I have a rolling average vehicle energy use of 14.8kWh/100 km and if we assume 90% charging efficiency then that would be 16.4kWh/100km. This is mostly low speed urban driving but with some regular 100km/h sections and using A/C about half the time. My range of consistently 285km.

WLTP will not be representative on long higher speed runs, especially on the MG ZS which has not got the most slick aerodynamics.

 

[Peter WA]

I have a rolling average vehicle energy use of 14.8kWh/100 km and if we assume 90% charging efficiency then that would be 16.4kWh/100km. This is mostly low speed urban driving but with some regular 100km/h sections and using A/C about half the time. My range of consistently 285km.

Those are some interesting figures. I've only done a single of those urban/suburban trips. A max of 90km/h for about 10% of the total distance, the rest almost evenly divided amongst 50/60/70/80 km/h sections with stop and go at traffic lights. On that trip I got 14.4 kWh/100km. Quite consistent with your figures.

If you multiply up your numbers 14.8 * 285 / 100 = 42.18. Some websites/blogs mention a 42 kWh battery size. Closer to the promised 44.5 kWh, but still short of it.

Do you ever use a DC rapid charger? Battery size would be:
100 * kWh billed / (battery % end of charge - battery % start of charge)

For me that figure consistently gets very close to 40kWh. And with the ODB2 readings showing that the battery only ever charges from 4% to 94% (even though the car display shows 0 to 100% to us), that is still my current working assumption of actually usable capacity.

Perhaps you have a different BMS version that makes a little more available to you?

WLTP will not be representative on long higher speed runs, especially on the MG ZS which has not got the most slick aerodynamics.

Of course. But neither is your usage scenario. WLTP contains a high speed section with speeds of up to 131km/h, and quite some time above 120km/h. Worldwide Harmonised Light Vehicles Test Procedure

Since wind resistance increases with the square of the speed, those high speed sections will use up a disproportionately large amount of energy, that's why the WLTP efficiency given in the advertising materials is 18.6 kWh / 100km, a lot more than what you achieved.

Back to my 4500km trip across Australia that I just completed:

While the WLTP test has lots of variable sections, there has to be one speed at which (with no wind or elevation change), the car achieves the WLTP range. Based on just looking at the WLTP test cycle, and knowing how disproportionately much energy is used at high speeds, my best guess would have been that this speed should be between 90 and 95 km/h.

In practice that did not eventuate. On days with with 20km/h tail wind I managed to get to WLTP range driving a constant 85 km/h. On days with sideways winds I had to drop to 80 or even 75 km/h to stop range from dropping away. I've only had a few hours of head winds during that whole trip: to keep the range constant I had to drop to 65, or, in the interest of safety, keep driving at 80 and accept a considerable reduction in range.

To summarise: there is no doubt that we can reach 263km or even more on one charge. Hyper miling is a thing, and for EVs that is easily achieved by dropping the speed*. The question that still remains for me is: did we get what we paid for? The advertised battery size in kWh and the range that comes with that?

* During my trip the day I got into most trouble was one where dropping the speed did not help: on an unsealed road, where dropping the speed below 70 meant that the corrugations used up a lot more energy.

 

[JodyS21]

For me that figure consistently gets very close to 40kWh. And with the ODB2 readings showing that the battery only ever charges from 4% to 94% (even though the car display shows 0 to 100% to us), that is still my current working assumption of actually usable capacity.

Perhaps you have a different BMS version that makes a little more available to you?

FYI

BMS (15/1):
Maximum charge 93.2%SoC
Minimum charge 0.5%SoC
SoC range available 92.7%.

BMS (7/2020)
Maximum Charge 97.0%Soc
Minimum Charge 5.0%SoC
SoC range available 92.0%.

 

[Peter WA]

I'm not sure when exactly my BMS is from, version number 0807620R32.

Tops out at maximum charge 94.0% Soc, with car on 100%, even after we equalising.
Lowest I've seen was 6% Soc when the car was down to 2%. Hence the assumption it's limiting to about 4%.

After initially telling us that all BMS updates are on hold in Australia we got news this week that a BMS update is now available. I won't be able to get it until after Easter, a friend should be quicker, I'll see what he get and how it affects the ODB2 info.

 

[Jeps]

WLTP is for comparing between different car models. I guess no one will tell you it is the holy grail, and achivble figures under all circumstances.
I am very happy with my purchase.

 

[TassiedEVil]

I have a rolling average vehicle energy use of 14.8kWh/100 km and if we assume 90% charging efficiency then that would be 16.4kWh/100km. This is mostly low speed urban driving but with some regular 100km/h sections and using A/C about half the time. My range of consistently 285km.

WLTP will not be representative on long higher speed runs, especially on the MG ZS which has not got the most slick aerodynamics.

Interesting - latest figures from down here... pretty much identical to yours Graham - mixture of driving conditions ( mountain, curves, highway at about 75 km/h and urban.

 

[Chippyinoz]

My figures to add to the discussion. Slightly higher average speed because to get anywhere from where I live there is a minimum of 10km at 90km/h but overall very consistent between us. The best figure I got on a long trip was 13.8kwh/100km when the motorway was crawling due to multiple crashes, slow speeds really do help!

 

[TassiedEVil]

Yes they do!! We’ve also been mixing it up more with Sport mode so will be interesting how that also impacts on range figures. I think aircon has been on sporadically but not all the time.

 

[Chippyinoz]

Yes they do!! We’ve also been mixing it up more with Sport mode so will be interesting how that also impacts on range figures. I think aircon has been on sporadically but not all the time.

Should have said, aircon has been on 95% of the time, one day I really want to test if the HVAC really makes the predicted difference to consumption but need it to cool down a few degrees yet for me to face a drive with no air!

 

[Tim Green]

I think if you drove quite slowly, say 50mph, with no heating on and in econ mode, you would probably get 163 miles from a granny charged battery. It would be boring and cold.
As people have pointed out, ICE cars quoted ridiculous figures for mpg and hence range which could never be achieved in real life. Also, Hybrid cars give mpg figures that are not achieved in practise. I have adked several owners of hybrids what they get and they say 40-45 mpg, which most ICE cars can achieve anyway.
Personally, I just use the MG like I would use any other car and recharge when necessary, just like an ICE car. Why all the fuss?

 

[Jeps]

163 miles is peace of cake compared to this

 

[JodyS21]

I'm not sure when exactly my BMS is from, version number 0807620R32.

Tops out at maximum charge 94.0% Soc, with car on 100%, even after we equalising.
Lowest I've seen was 6% Soc when the car was down to 2%. Hence the assumption it's limiting to about 4%.

After initially telling us that all BMS updates are on hold in Australia we got news this week that a BMS update is now available. I won't be able to get it until after Easter, a friend should be quicker, I'll see what he get and how it affects the ODB2 info.

Ooh, you've got a slightly different BMS (0807620R32) to what we've got in our list!

ECU Module version spreadsheet

I'll update this top post as more data is provided. In an attempt to figure out what the different versions of all the software do/cause, we are putting together a list of peoples car ecu versions. If you have the OBD2 device (currently being looked at in another post) or OVMS, please post your...

www.mgevs.com

The 7/2020 BMS car those figures are from is 0603610R28 (455V btw)

We ran them to totally flat when it shut off, to get those minimum figures.

 

[JodyS21]

I'm not sure when exactly my BMS is from, version number 0807620R32.

Tops out at maximum charge 94.0% Soc, with car on 100%, even after we equalising.
Lowest I've seen was 6% Soc when the car was down to 2%. Hence the assumption it's limiting to about 4%.

After initially telling us that all BMS updates are on hold in Australia we got news this week that a BMS update is now available. I won't be able to get it until after Easter, a friend should be quicker, I'll see what he get and how it affects the ODB2 info.

@Peter WA

Was re-reading the conversation about you only seeming to get 40kW DC into the car....
Car display 3% to 78% = 75% @ 30kWh : Therefore 100% is 40kWh.

Now we know about how the SoC% is related to the car dash %.
You have an unknown BMS version, but I think (can you confirm) you have a 455V version.

The Usable SoC range from tests is between 92-92.7% let's call it 92.35%
(This relates to a dashboard charge% of 0-100%)

Therefore:
30kWh at a dashboard of 75% gives 40kWh for 100% dash.
40kWh is 92.35% of the actual battery capacity
Actual battery capacity would be (40 / 0.9235) 43.313kWh
Still not 44.5kWh but it's definitely closer and, with a bit of tolerance/under ideal conditions it may make it to 44.5kWh?

 

[Peter WA]

Why all the fuss?

Because a 10% difference in usable battery capacity, that results in a 10% difference in achievable range has implications in day to day use of the car in any country that lacks a very dense network of chargers.

And what about truth in advertising? I would not have bought a car with 236km WLTP range, because, even after just a 20% degradation in battery it will make it impossible to do some of the day trips I do without having to find a charging option along the way, detouring, and wasting time. Or driving slow, wasting time.

Just as VW customers who were duped into buying dirty diesels should be compensated, so should we if we have been short changed on usable battery capacity.

 

[TassiedEVil]

Because a 10% difference in usable battery capacity, that results in a 10% difference in achievable range has implications in day to day use of the car in any country that lacks a very dense network of chargers.

And what about truth in advertising? I would not have bought a car with 236km WLTP range, because, even after a 20% degradation in battery it will make it impossible to do some of the day trips I do without having to find a charging option along the way, detouring, and wasting time. Or driving slow, wasting time.

Just as VW customers who were duped into buying dirty diesels should be compensated, so should we if we have been short changed on usable battery capacity.

It might be worth contacting Choice (an Australian consumer affairs advocacy group) with your findings/concerns. Im sure this isn’t going to be the first or last instance of ‘bendy’figures. You never know - it might flush MG Australia out into the open to discuss If they want more buyers, they need to explain WLTP, how it’s calculated and just what is the difference between advertised battery capacity and useable capacity. Informed owners are happy owners and are the best and cheapest advertising available.