I'm buying an Orbea Orca Bli2 which has Ultegra Di2 shifting and I'm worried about running out of battery life on long distance events. For example, I am starting to train for next year's Endless Mountain 1240 which is 770 miles. That's over all the estimates for battery life that I've heard.
Does anyone do rides these lengths with Di2 shifting or know anyone who does? Does it last or do you have to replace the battery at some point?