I built a 24V 20AH pack with Thundersky cells this spring. I haven't had an opportunity to take a long trip yet but I've done a lot of 20 mile trips and still had plenty of power (my logs from the CellLog 8 have shown over 26V remaining after those 20 mile trips). I'm planning on going to a town that's farther from me once our weather improves--that trip will be a little over 40 miles. I don't think I'll run out of battery power--I'll have my Thundersky pack and my original SLA on the rear rack. I'm so happy with my Thundersky pack that I'm planning building a second pack this summer. It makes a huge difference to go from 10AH to 20AH.