Wrong Kjoules Calculation with Assioma Favero Uno and Garmin Fenix 7

Hi, today I bought my first power meter for outdoor riding, the Assioma Favero Uno. I record my activities with a Garmin Fenix 7
I’ve been using the Wahoo Kickr Core during the Winter and always looked at the ‘Total Work’ metric calculated in kJoules.
The number for this calculation result is mathematical , so no different algorithms based on the headunit.
Today I did 168W average power for 1h28min , which should result in 887kj , however the number I got was 785kj.
Instead with my Wahoo Kickr , on a different ride , and same Garmin Fenix , the numbers are correct. Example 160w avg for 35min results in a precise 336kj
I allege some photos of the two rides


Do you know the reason why?

That is interesting - I love a head scratcher :grinning:

The only thing that comes to mind is it’s something to do with how “zeros” and “nulls” are treated during the average power calculation?

I think if there is a difference anywhere it will be with the average power reading - is it possible that you were not pedalling for ~10mins of the 1h28 ride?

If there was only power readings for 1h17 of that 1h28 ride, and the average power was only calculated from the points where power data was present, then you would get something similar to what you are seeing.

TL;DR
The “work” result is probably correct and the average power and/or activity time is not like-for-like.

Was the time for the outdoor ride moving time or elapsed time? If you have auto pause on this could be something. The average is calculated over the moving time.