Bike Range

I've been riding my ebike a lot lately.  I have a Trek Allant +8 ebike and I don't know the maximum range for my bike.  The bike has four settings, Eco, Tour, Sport, and Turbo,  Each setting gives me a different level of assist while I bike.  It is easy to understand why there is no easy answer to this.  Check out the on range calculator the Bosch website, there are so many different factors that change your bike range.  Not only does it depend the level of boost, but also how fast I bike, the hilliness of the route, and the road surface.  

The app on my phone is gathering data, learning my biking patterns to predict the range.  I have no idea how well that works.  When I start riding my bike at at Eco it says the range is 78 miles.  After I ride one mile on Eco my range says I have 68 miles left.  Looking at the range predictor is not totally reliable.    

I figured out that I can use my rides to work.  It is a 20 mile round trip and I know the ride well enough that I can stay in one boost for the whole ride.  

On Turbo I use 85 % of my battery on a 20 mile round trip ride. On Sport I use 65% of my battery, giving me a range of 35 miles. On Tour I use 45% of my battery, that would make the range 50 miles.  On Eco I use 30% of my battery over 20 miles.  That gives me a range around 65 miles.  

I know I really need to do each of these rides 10 times to truly understand my bike's range.  I'm not sure I'll really do that kind of study.  I don't expect to do more than a 40 mile total ride in any day.  I know I can do  this with good management.

There is part of me that ways to get extra battery for my bike.  It is expensive, but it would really boost my bike range.