MG5 Trophy Real World Consumption Thread

[Ian W]

These numbers for cold weather are weird. My own experience is that city driving in cold weather is much less than 205 miles — more like 140 miles. I think this is because it’s split up into 15-20 miles a day (and that in two trips) so the car has to warm up every time. Perhaps if I were to actually drive in a city non stop for 205 miles it may achieve that, but cities aren’t that high, in mega city one I’d be using a flying car

Hi from NZ. Just got a zs EV 51kwh, all that's available from mg here atm but loving it.
Anyway, with display showing trip stats when doing my usual 9km (sorry) trip to/from work, reading only shows after 1km but is high, 22kwh/100k (sorry again) before dropping slowly to 16 (equivalent to wltp rating) or lower if I'm careful...it's still warm here.
Any ideas? High uncertainty of distance measurement given it doesn't display at all until 1km?
Seems a bit odd at first blush, Ian.

Well here's a lesson for me on my first post, think a little longer. The answer is that the energy required to get up to speed, 80kph in my case, dominates the energy in the first km, expaling why mg waits a km before displaying trip energy. A quick estimation is 0.2 kWh, a little more given inefficiencies, and the mean energy use at the wltp rate is 0.17 kWh per km. So, obvious in hindsight even though I was blindsided for a while. And sorry again for the km instead of miles but second thoughts again, not sorry?

 

[Georgie]

Driving on the A46 mostly uphill, M4 east 50-70mph, M25 40-70mph, M1 north. Several stops on the way. Temperature outside from 12 degrees when we started the journey to 5 degrees when arrived around 9 pm. Aircon on and off but heating on at 20 degress. Battery heating on for around one hour of the journey before the stops.

 

[Gomev]

Driving on the A46 mostly uphill, M4 east 50-70mph, M25 40-70mph, M1 north. Several stops on the way. Temperature outside from 12 degrees when we started the journey to 5 degrees when arrived around 9 pm. Aircon on and off but heating on at 20 degress. Battery heating on for around one hour of the journey before the stops.
View attachment 16610

Very good figures.
Slightly confused though, you did 160 miles at 4.2 but had 'stops' that required battery heating ?

 

[Georgie]

Very good figures.
Slightly confused though, you did 160 miles at 4.2 but had 'stops' that required battery heating ?

I didn't say required battery heating. I'm trying to do a sort of reverse engineering here.
Without any battery temp gauge and the decision from the BMS information it is not possible to know the BMS strategy. Also I would guess that if the batt heating is not required the BMS would just stop it.

When charging at Reading East moto services the batt heating stopped - based on ismart info - and the charging rate was aprox 60KW from 60% to 80% SOC. On the west journey without the batt pre-heating, sligthly warmer temp outside, the charging rate was aprox 40-47KW from 60 to 80% SOC. Both times using Gridserve at Reading services.

 

[Les burrows]

I didn't say required battery heating. I'm trying to do a sort of reverse engineering here.
Without any battery temp gauge and the decision from the BMS information it is not possible to know the BMS strategy. Also I would guess that if the batt heating is not required the BMS would just stop it.

When charging at Reading East moto services the batt heating stopped - based on ismart info - and the charging rate was aprox 60KW from 60% to 80% SOC. On the west journey without the batt pre-heating, sligthly warmer temp outside, the charging rate was aprox 40-47KW from 60 to 80% SOC. Both times using Gridserve at Reading services.

Hi Georgie, so your saying the the BMS controls the battery heating so why have MG provide use with a switch to operate it ? and then recommend using it in certain scenarios like types of weather conditions.
Les

 

[Georgie]

Hi Georgie, so your saying the the BMS controls the battery heating so why have MG provide use with a switch to operate it ? and then recommend using it in certain scenarios like types of weather conditions.
Les

Apologies for the long winded answer.
Imo it is mainly because heating with the resistive heater is a very expensive process.
The battery heater is described as 7KW somewhere in the MG literature so it should draw around 17A for full battery at 406V. But the fuse F11 (battery heater) is rated at 15A. So a bit less than 6KW but still a lot of wasted energy. The heating will likely be variable using PWM so it wouldn't draw continuously max current.
Cooling on the other side should be way less expensive because of the AC efficiency. I couldn't find a figure for the AC rating but would expect 2 to 5 times more efficient. Hence the argument for heat pumps and the ridiculous price car manufacturers charge for this option.
Cooling is critical but heating is mainly required to improve efficiency during driving and charging.
Here is an article about the effect of temperature on the LiB ageing/degradation. Temperature effect and thermal impact in lithium-ion batteries: A review

While driving and charging, the battery will heat anyway to a certain level depending on various factors. In cold weather let's say less than 10 degrees C it might still not be enough.

MG decided to leave it to the user if they want to use the extra charge to warm up the battery while driving and sacrifice some of the range. But they didn't give the option to switch it off during charging as the strategy is to shorten the charging time.
Tesla and probably others offered to further automate the preheating process by optimising the batt heating until the chosen charging destination. It's still a bit of a guess.

 

[Alan59]

So, from that academic paper, our MG5 battery performance drops off below 15C and above 35C. Who knew? Well, pretty much everyone on this forum, I'd guess! This forum does a great job of informing newbies to the MG5, such as myself, about the real world impact of temperature, weather and lots more besides on range and efficiency - keep up the good work, folks, you provide an easier read than that paper was. For more detail, see my paper, "Brain Performance As A Function of Cups of Coffee Drunk Before 8AM") Have a goid day, all ?

 

[Gomev]

I didn't say required battery heating. I'm trying to do a sort of reverse engineering here.
Without any battery temp gauge and the decision from the BMS information it is not possible to know the BMS strategy. Also I would guess that if the batt heating is not required the BMS would just stop it.

When charging at Reading East moto services the batt heating stopped - based on ismart info - and the charging rate was aprox 60KW from 60% to 80% SOC. On the west journey without the batt pre-heating, sligthly warmer temp outside, the charging rate was aprox 40-47KW from 60 to 80% SOC. Both times using Gridserve at Reading services.

So I guess you were just 'playing/experimenting' fair enough.
Starting from 60% SOC will obviously not offer charging speeds as fast as a lower SOC.
I generally find after a drive of around 150-180 miles, which is when I would usually stop for my first top up (which was why I was puzzled you stopped twice to top up in a 160 mile journey), with SOC anywhere between 20-35% that the battery is plenty warm enough from the driving and I have achieved over 90kW from an Osprey charger at 34%.

 

[Les burrows]

I went out today to try and prove a point to myself which I think I did. In my MG5 Trophy.
As I have said many times these short journeys with high MPKW mean next to nothing in my book there are far too many variables which can and do make a difference to the MPKW figures.
So today I did a short journey of around 40 miles and paid attention to the battery percentage.
When I started the car was showing 50% so I drove for 21.4 miles with the car in the default setting of Comfort regen level 2, so 21.4 miles used 10% of the battery then I turned around and drove back exactly the same route trying to drive to the same speeds as much as I could mainly M6 and M56 motorways holding 50 mph for around 60% of the drive due to the roadworks on the 6 and the rest up to around 62-65 mph.

So on the way back I set the car in Eco regen 1 and got the exact same result 20.4 miles this time don’t know where I lost a mile but again 10% of the battery was used most of the outward the MPKW was at 3.7 and one the return 3.9 but in the picture you will see 4.1 that was because of a little bit of traffic for around the last 1/2 mile.
So I have said in the past the car does 2miles for 1% of battery so at 100% of charge you will get 200 miles but 3.8 equals 220 miles MG motors in there advertising say the cars efficient is 3.6 MPKW and 230 miles so using their figure of 3.6 that gives 208 miles all this figures are based on a 58 kw usable battery so 230 miles I have yet to see it

The first picture is after the first leg yes I know it shows Eco 1 but I had just reset for the return
Les

And then the return drive

 

[m4rmite]

100 Mile trip to bath, so mainly motorway.
On way there the temp was between 2 and 6 degrees so the heating was on 21c 99% of the way. 65mph when on the motorway and averaged 51.7 mph. Ended up with 3.3mpkwh.

Return trip it was 10-14 degrees and i took a different route back to the m5 as there was a road closure showing on the a46.
I also went somewhere for breakfast just outside of Bath.
Fan on 16c but not ac.
65mph where possible but more traffic on way back with more down to 50 up to 70mph Traffic dependant.
3.9mpkwh with an average of 50mph.
All on eco , but eco heat/cool button turned off.

Stopped at saltford, flourish farm house for breakfast, and they have 6 x120kw instavolts and 4 x 7kw pod point chargers.