Wow! that is sure a great explanation, it's hard to get your head around the figures but I think l nearly understand what you are saying. l also would be keen to hear what MB say about it. my EQA average from reset is 2.6mkw and last nights charge to 80% said l had a range of 181miles, however on this mornings trip out the first 5miles of actual driving used up 10 miles of range due to driving condition etc so it is very much a guessometer.
Did you preheat the car before you left? I did on my journey out today and the range dropped by exactly the no of km covered but coming back I did not the car was standing about an hour and half so it had to work to reheat the cabin. I “lost” 28km range when I had driven only 23 so 5 short and that will have been because it was heating the car as well as driving it.
I have done some very rough number crunching on the journeys-:
out = 47% SOC to 37%
8% = 6.4kw used (8 x .8 as the battery is rated 80kw)
Reported consumption on the eco coach app 24.5kwh/100km
distance = 23km therefore at .245 per km 5.63kw
.765kw less than used according to the battery SOC could be a rounding up error
return = 37% SOC to 28%
9% = 7.2kw
reported consumption 25.9kw/100km I always use more on the way back on this regular trip
distance = 23km therefore at .259 per km 5.88kw
1.24 kw less than used and a bigger difference not to seem an obvious rounding up error.
Combined stats from the mercedes me app trip meter
46.4 km ar 25.3 kwh/100km
finish 28% SOC
45 - 28 = 17% x.8 = 13.6kw
46.4km x .253 (rate per km) = 11.73kw
= 1.87kw used extra
So where is the extra going? The manual states that the 12v battery runs the lights, indicators and periperals like the display screen, one assumes as it is all 12v given it is used in non electric cars as well. However the heating and air con are run from the high voltage battery which is why if you have the car plugged in to a wallbox and ask it to preheat it will start drawing power from the wallbox ( I know this from the readings on my EDF app showing my electricity usage in half hourly segments) and I have noted also it will actually put charge into the battery if left long enough.
So on my journey today I used 13.6kw to actually drive the car and a further 1.87kw to heat and maintain its temp ( I leave the aircon on all the time). Clearly ICE cars can utilise the heat from the engine which is just wasted otherwise but electric cars have to generate it as there is very little produced by the movement of the car.
Looking at the range of 90km for a 28% charge at an overall 25.1kw/100km since reset charge over 5003 km as of this evening :-
28x .8 = 22.4kw
22.4 /25.1 = .8924 rounded up 90km
All these stats show how the range is not precise but an indicator of what you might achieve. If I prewarmed the car with it plugged in and then turned the heating off and had a good run to improve my average consumption for the journey I will get more than the 90km but if I donot pre warm and have a bad run probably a lot less. Heating is a big user.
There is a screen in the EQ section that shows you what the consumption is seperated out for heating, for driving and one for accessories the heating is often 6 to 8% of consumption but I have never paid great attention to it.
What is perhaps disappointing is that the range or guessometer does not inc an allowance for heating it would be good if perhaps you could toggle between them ie one of efficiency only as now and one using a rough calculation if full heating is needed, but I shall have a look at average % consumption to try and see if there is a ballpark figure I can work to.
However for me it has not been a concern as I simply work on the basis of whether Ithink 50% SOC will leave me enough for my needs. I try to avoid charging in the day Mon, Tues and Thurs Fri as I pay full rate, after 10.30pm until 6.30am and all day Weds Sat and Sun I get a cheap rate. If it was the same all day everyday I would just plug in as soon as I got home to keep the car topped up.
This is a long winded post but I hope people can follow my non mathematical logic. Manufacturers really should be taking people through these issues when they are considering buying an electric car and they should have a detailed explanation of all these elements in the car manuals. I have checked mine and there is nothing explaining how the range is calculated and what it actually indicates nor how the heating using power reducing the range more than you might expect as it is not incl in the efficiency (mpk kw/100km) figures used to achieve the range figures. Failing to do so is resulting in disatisfied customers who think the car is either faulty or that they have been sold a car that does not achieve what they felt they were told it will.
Really appreciate if Des can update us on his issues when he has spoken to his garage and had the car inspected.