Rapid Charging, Just how far must you drive before 50KW is seen?

[WAC 768]

With the claim from MG, you can charge your car from 0 - 80 using a 50KW rapid charger in just 40 minutes; I thought i would put this to the test, given; I have rarely seen this speeds anywhere close to this. Now before i start yes, i am aware this is subject to outside temperature and SOC but for the latter and with the new BMS, it's only starts to flatten at around 80% (MG Claims not mine).

Here's my results and the route taken was a 50 - 50 split using a mixture of A roads (dual & single carriageway)

And you can see from the table above, using the same charger for the first 2 and in fairly mild weather it's well over 100 miles before the car is capable of accepting 50KW or greater (charger dependent) to achieve the mythical 40-minute charge time or less.

Now, i believe 25C is the optimum temperature for the battery, but anything between 15C - 30C is classed as the 'desired operating temperature', so would expect once above the lower limit 50KW should be achievable without having drive many miles before hand to bring the pack temperature upto the optimum, but clearly not in my case!!

Interested in your thoughts / comments on my findings

 

[micky]

With the claim from MG, you can charge your car from 0 - 80 using a 50KW rapid charger in just 40 minutes; I thought i would put this to the test, given; I have rarely seen this speeds anywhere close to this. Now before i start yes, i am aware this is subject to outside temperature and SOC but for the latter and with the new BMS, it's only starts to flatten at around 80% (MG Claims not mine).

Here's my results and the route taken was a 50 - 50 split using a mixture of A roads (dual & single carriageway)

View attachment 3208

And you can see from the table above, using the same charger for the first 2 and in fairly mild weather it's well over 100 miles before the car is capable of accepting 50KW or greater (charger dependent) to achieve the mythical 40-minute charge time or less.

Now, i believe 25C is the optimum temperature for the battery, but anything between 15C - 30C is classed as the 'desired operating temperature', so would expect once above the lower limit 50KWH should be achievable without having drive many miles before hand to bring the pack temperature upto the optimum, but clearly not in my case!!

Interested in your thoughts / comments on my findings

hi wac768 i can see all your chargers are BP pulse is it possible to use 3 different type chargers to get a far better average..

 

[WAC 768]

hi wac768 i can see all your chargers are BP pulse is it possible to use 3 different type chargers to get a far better average..

I used BP pulse just for consistency, but I have also used BP, Shell and InstaVolt in the past with the same result.

 

[nicko1]

I used BP pulse just for consistency, but I have also used BP, Shell and InstaVolt in the past with the same result.

oh

 

[Deleted member 2439]

With the claim from MG, you can charge your car from 0 - 80 using a 50KW rapid charger in just 40 minutes; I thought i would put this to the test, given; I have rarely seen this speeds anywhere close to this. Now before i start yes, i am aware this is subject to outside temperature and SOC but for the latter and with the new BMS, it's only starts to flatten at around 80% (MG Claims not mine).

Here's my results and the route taken was a 50 - 50 split using a mixture of A roads (dual & single carriageway)

View attachment 3208

And you can see from the table above, using the same charger for the first 2 and in fairly mild weather it's well over 100 miles before the car is capable of accepting 50KW or greater (charger dependent) to achieve the mythical 40-minute charge time or less.

Now, i believe 25C is the optimum temperature for the battery, but anything between 15C - 30C is classed as the 'desired operating temperature', so would expect once above the lower limit 50KWH should be achievable without having drive many miles before hand to bring the pack temperature upto the optimum, but clearly not in my case!!

Interested in your thoughts / comments on my findings

Are you aware that you are using KW & KWH inconsistently?

 

[WAC 768]

Are you aware that you are using KW & KWH inconsistently?

I presume you are referring to the tab that looks like KW? This is actually KWH it's just the filter that's hiding the 'H'

 

[Deleted member 2439]

I presume you are referring to the tab that looks like KW? This is actually KWH it's just the filter that's hiding the 'H'

No, I was actually referring to the mention in the last full paragraph. You are taking about reaching the 50 KWH limit, but it should be 50 KW - which is a measure of power. Google “kWh vs kW“ & all will be explained.

As an electrical engineer I am drawn to people making mistakes such as this, but don’t worry, you ain’t the only one to do it.

 

[WAC 768]

No, I was actually referring to the mention in the last full paragraph. You are taking about reaching the 50 KWH limit, but it should be 50 KW - which is a measure of power. Google “kWh vs kW“ & all will be explained.

As an electrical engineer I am drawn to people making mistakes such as this, but don’t worry, you ain’t the only one to do it.

OK, perhaps my title was incorrect and should have said KW, Regardless though, the amount of energy supplied in my table (Charge KWH) clearly shows that to get 33KW (0-80%) takes longer than the 40 mins MG claim unless and in my case i drive more than 100 miles and this moreover the point i was making

 

[Deleted member 2439]

OK, perhaps my title was incorrect and should have said KW, Regardless though, the amount of energy supplied in my table (Charge KWH) clearly shows that to get 33KW (0-80%) takes longer than the 40 mins MG claim unless and in my case i drive more than 100 miles and this moreover the point i was making

It would be interesting to know at what temp MG established the spec they are quoting as it seems the cells behave differently with temp.

 

[JohnG]

I did some testing last week here in Norway to see what charging speed I would get with a car that has the latest BMS SW that fixed the cell imbalance issues. I am using the Thai MG EV app which shows the battery temperature. Outside temperature was 20 c and the car had not been driven very far before I started to charge (9km). Start SOC was 6% and battery temp displayed was 22 c. I am sssuming had I arrived with the battery temp > 25 c the charging speed would have been a bit higher. The charger was 150kW and I was the only car charging. Highest charge speed I saw was 72.8kW at 8% SOC and highest batttery temp was 35 c at 33% SOC. Fastned in Holland say the battery should be at around 30 C to get the best charging speed. I compared the curve they display on their website for the ZS and they show a peak of 76kW at about 16% which then falls more or less in a straight line to about 46kW at 50%.

Charging with a MG ZS EV

If you drive a MG ZS EV, then you use the CCS connector. It could be that there is a plastic cover, covering the bottom part of the charge port. If so, this plastic cover needs to be removed in ord...

support.fastned.nl

If you look at the charge curve below it would seem that the latest BMS has upped the speed considerably between 25%-51% SOC which is when I stopped charging. The curve from 10% to 38% is flatter and from 40% -50% also flat with speed actually increasing from 47%. A charge from 6% to 51% added 18.03kWh which equates to an average charge speed of 62.4kW which IMOP is not too shabby. Added range based on WLTP and a useable battery of 42.5kWh in just over 17 mins equates to 71 miles (113km).

 

[Deleted member 2439]

This is quite interesting from a philosophical perspective as well as the technical/physics one. As early adopters we are discussing this rationally, trying to understand and make sense of the situation- which is great. HOWEVER, I think the average driver will be totally confused by all this especially given the marketing type aspects which are all mixed into the equation. Everyone is so used to filling the tank of their ICE car in a minute or so and I can see confusion reining amongst the wider population whose new EV is taking much longer to charge than they had been led to believe - on top of the “promised” range being somewhat less.

The first time I tried a rapid charger it was giving a rate of 22kW, the second time (different charger), 28kW. I was intrigued and discovered that temperature was to blame, being close to freezing. However, I understood why and accepted it. I’m not sure that all people would though, especially if running late and think that there was something wrong with the car.

EVs are a paradigm change for sure, with this aspect lurking in the background. Another one which has piqued my interest in the last day or so is a YouTube item by an electrician regarding the issues around a home charger installation. It seemed to be straightforward enough at first, but very quickly escalated with every aspect of the job presenting a challenge to resolve. On this occasion he had an informed customer, but I can see many not being so or seeking a lower cost “sub-optimal” installation. If anyone is intereste, search for Artisan electrics on YouTube & you will find it.

 

[WAC 768]

I did some testing last week here in Norway to see what charging speed I would get with a car that has the latest BMS SW that fixed the cell imbalance issues. I am using the Thai MG EV app which shows the battery temperature. Outside temperature was 20 c and the car had not been driven very far before I started to charge (9km). Start SOC was 6% and battery temp displayed was 22 c. I am sssuming had I arrived with the battery temp > 25 c the charging speed would have been a bit higher. The charger was 150kW and I was the only car charging. Highest charge speed I saw was 72.8kW at 8% SOC and highest batttery temp was 35 c at 33% SOC. Fastned in Holland say the battery should be at around 30 C to get the best charging speed. I compared the curve they display on their website for the ZS and they show a peak of 76kW at about 16% which then falls more or less in a straight line to about 46kW at 50%.

Charging with a MG ZS EV

If you drive a MG ZS EV, then you use the CCS connector. It could be that there is a plastic cover, covering the bottom part of the charge port. If so, this plastic cover needs to be removed in ord...

support.fastned.nl

If you look at the charge curve below it would seem that the latest BMS has upped the speed considerably between 25%-51% SOC which is when I stopped charging. The curve from 10% to 38% is flatter and from 40% -50% also flat with speed actually increasing from 47%. A charge from 6% to 51% added 18.03kWh which equates to an average charge speed of 62.4kW which IMOP is not too shabby. Added range based on WLTP and a useable battery of 42.5kWh in just over 17 mins equates to 71 miles (113km).


View attachment 3260

Thanks for the detailed information and from this and based on other comments, then i would expect if on a 50KW charger the rate to the fairly flat with little drop off until nearer the 80%. What though i can see is the temperature of the pack increases significantly, which is something i've not seen.