Here are the results of a unscientific test I did on the performance of my Orbea Gain battery.
Hopefully this may help potential buyers and pertinent to a few recent posts will include my findings on the performance of the battery
when on it's last 25% of charge.
As with all e-bikes the largest single variable is the rider, and so for newcomers here who haven't 'slogged' their way through 60 odd pages
I include the following. I am 73 years of age and approx 71kgs. The last few years I have ridden 4,000- 5,000 miles a year shared between
my Gain and an indoor trainer setup with a dedicated bike on a Tacx Neo smart trainer.
My Gain is a 2019 D30 (shimano 105) which has completed 2,885 largely 'blameless' miles. It is fitted with full mudguards
and rides on 38mm 'gravel' tyres. On the road with water bottle and my added accessories it weighs approx 16.5 kgs !
I ride almost exclusively in the lowest assistance setting and I have my 'engine settings' at Lowest=90%.  Medium=80%. High=70%.
This 'test' came about after reading the MAHLE ebikemotion page advice/recommendations that include:-
"How to calibrate the battery: Advice is to periodically discharge the battery to 0% before recharging to 100%
Prior to this test my battery had never been discharged to 0% and has been overwhelmingly used in the 25>85% range.
So my battery was 'run down' to 0% and charged to 100% and for clarity I will detail my 7 rides over 10 days.
          Miles/    Time/        Avg speed/     Elevation Gain/     Battery used/     Battery remaining
1.      19.89      1:15:14     15.9mph        558ft                     12%                    88%
2.      23.99      1:27:53     16.4mph              774ft                  13%                    75%
3.      16.50      1:00:49     16.3mph              449ft                      12%                    63%
4.      23.37      1:30:12     15.5mph          1,247ft                  22%                    41%
5.      19.15      1:09:34     16.5mph          891ft                     14%                    27%
6.      19.13      1:07:00     17.1mph           890ft                   11%                    16%
7.      19.15      1:08:53     16.7mph           892ft                  11%                      5%
(N:B Ride 5/6/7 same route)
.
Totals.......................................................................
       141.18 Miles          16.34 Avg  speed         5701 feet                     95% used                    5% remaining
Observations. I have to be happy with the total mileage but not a lot of climbing involved (bearing in mind the mileage)
The total mileage would fall significantly as the Elevation gained increased.
Ride 7 I felt 'knackered' from the start, borne out by comparison with ride 6 but 11% battery used on both rides ?
All rides only lowest assistance used.
Rides 5/6/7 were chosen to gauge battery performance over the same course/conditions over the last 27% of remaining battery charge.
I see no significant difference in these 3 rides, and my battery seems to discharge linearly ?
I guess battery discharge may seem inordinately high towards the end of a ride, if you have maybe increased the assistance level ?
You are tired and your cadence has slowed ? I understand the Gain motor balances power output against rider input based on cadence.
There is no torque sensor as on some e-bikes.
Ok, I have filled an hour or two and exercised my tiny brain doing this but feel free to tell me if you think I'm talking 'tosh'
P.S  Oops !  I tabulated the Miles / Time / Avg Speed  etc and it shows fine on my hard copy but after submission the tabulation is missing ? Hope it makes sense ?