Audi e-tron Forum – News, Specs, Pricing & Ownership… banner
1 - 14 of 14 Posts

·
Registered
2020 etron 50 Black Edition
Joined
·
57 Posts
Discussion Starter · #1 ·
Ok, I will try and keep this brief.
I have been trying to establish the maths behind the GOM. I have assumed that it works out your range based on the previous driving habits. But how much of that data is it taking into account? I thought this can't be that hard to work out how many previous data points are being used to calculate the range, as you have all the date in a spreadsheet!
so I have been downloading the driving data and analysing it - created some different total average options, and comparing the range calculated by using different no of data points and comparing that with what the app says at the time.
Starting with the whole data set - this doesn't match.
The closest match I can get is when using the previous 9 10, or 11 data points. this bring me to within 1% accuracy. But it is not the same no of data points each time.
I would upload the file but I can't seem to attach excel sheets here.
My driving is mostly town and ranges between 1.7 and 2.5 mi/kWh, and its very obvious when I get out of town that the regen brings in a higher level of efficiency getting up to almost 3 mi/kWh.

Here's a screenshot.
1894


Any additional pointers welcome...

Hope that's interesting ..
 

·
Registered
e-tron 50 technik
Joined
·
260 Posts
I'll be interested to see how the calculation is made. Thanks for posting your readings.

I think the current ambient temperature must be used by the GOM. Maybe also the battery temperature in addition, in fact my recent observations suggest the battery temperature is used primarily. For example in the UK recently we've had warm days (upto 22°c around here) and cold (around 0°c - 3°c) nights, come morning the battery has retained a bit of the previous day's heat and efficiency+GOM range are higher as a result despite 0°c-3°c ambient temps when checking these readings.

Might be worth looking back and adding ambient temperatures at the time of each journey?

Also the useable battery for the etron 50 is 64.7kWh as far as I understand. Which may alter your calculations. Correct me if I'm wrong.
 

·
Registered
Joined
·
190 Posts
Interesting! Since you've possibly discovered that the GOM uses different numbers of data points, possibly look into whether it doesn't take into account super short trips.
Take a few 5 minute "around the block" drives and the GOM may just not account for it in future prediction because it isn't typical?
 

·
Registered
2020 etron 50 Black Edition
Joined
·
57 Posts
Discussion Starter · #4 ·
Good feedback guys - I think taking out trips would be a long process of trial and error. But I might try and exclude certain very short trips in the total data set and see if that gets it closer
 

·
Registered
Joined
·
1,066 Posts
Cabin conditions, etc, are pretty involved in the GOM algorithm, I think. When I turn on my A/C button, my GOM reading immediately drops a few miles.
 

·
Registered
Joined
·
48 Posts
Good feedback guys - I think taking out trips would be a long process of trial and error. But I might try and exclude certain very short trips in the total data set and see if that gets it closer
Have you tried running the A/C in economy mode?
 

·
Registered
2019 Audi e-tron Launch Edition 55
Joined
·
160 Posts
I also think that the calculation only rounds to one decimal place, e.g 1.7, 2.3 kWh. When you download the data in CSV form you can see that additional precision is not recorded, meaning that the best the GOM can ever do is to report the same multiples (the battery doesn’t change size [though over time we know it will], and it’s probably always charged to 80% say).

Therefore multiples of the kWh available and mi/kWh will often yields the same fixed results.

e.g (83.6 kWh * 80%) * 2.3 mi/kWh = 154 miles
2.4 = 160
2.5 = 168.

So I always see figures like 140, 147,158 mi etc even though I know that this is probably just a decimal point difference - despite of course natural variations in weather and previous driving efficiency.

I have also observed double counting of individual trips in the CSV data which record slightly different start and finish times on the same day. I’ve seen this for journeys of >100 miles so it’s impossible that I’ve actually done that distance twice within the same couple of hours. How that even happens I have no idea! But look through enough data and you’ll see it.

In summary the calculation seems quite simplistic and after allowing for the discrepancies above I think it probably uses no more than a handful of data points. I find that the range cloud (blue shaded area on the map) is a better indication of real range, but you have to be undertaking quite a long journey for this to adjust itself (and it keeps pushing out until range no longer increases and then starts to decrease). This is probably where it gets interesting!
 

·
Registered
Joined
·
360 Posts
Also the useable battery for the etron 50 is 64.7kWh as far as I understand. Which may alter your calculations. Correct me if I'm wrong.
Now thats what I thought and according to searches etc thats what has always been quoted, but quite interestingly I found an area on the MyAudi app that quotes slightly differently and I wouldnt mind some others checking this please (even on the 55's) as it may affect your calculations too @RICH290.

In the MyAudi app, if I go to "My Vehicle In Detail" and click Equipment and technical data. On the next screen, I click Technical data/consumption., then select Electric Drive.

This shows "Hybrid battery energy content nett: 64,0 kWh"

Does that mean mine only has net use of 64 kwh not 64.7?

1913
 

·
Registered
Joined
·
1,066 Posts
Are the numbers you are quoting "usable capacity"? Remember, the car is blocking out 12%(2019) or 10%(2021) of capacity.
 

·
Registered
e-tron 50 technik
Joined
·
260 Posts
In the MyAudi app, if I go to "My Vehicle In Detail" and click Equipment and technical data. On the next screen, I click Technical data/consumption., then select Electric Drive.
Good find, mine's the same.

Are the numbers you are quoting "usable capacity"? Remember, the car is blocking out 12%(2019) or 10%(2021) of capacity.
That'd just about explain it. Thanks!
 

·
Registered
Joined
·
360 Posts
Are the numbers you are quoting "usable capacity"? Remember, the car is blocking out 12%(2019) or 10%(2021) of capacity.
The battery capacity on a UK Etron 50 is 71kWh, with a reported usaeable battery of 64.7 kWh. I was therefore thinking that my 'nett' figure shown in the specs should be 64.7 not 64.0.

Apologies @RICH290 - didnt mean for this to go off track to discuss this - mods please separate if required - @RICH290 it may effect your figures though if your nett is shown as slightly less than the reported nett useable figure though perhaps?

Out of interest as well, which of the initial columns above in your spreadsheet are brought in from the stats on the app - I cant seem to pull kWh used from my stats in MyAudi - have you added that in from podpoint info / charger info?
 
1 - 14 of 14 Posts
Top