This is a handy way to have the extra power for bike use when camping off grid for extended periods. Unless you have an elaborate solar power setup, it takes quite of bit of time to totally charge up the larger batteries. It adds extra weight to the bike, but that's not a big issue for my particular use. It would be a smart idea to drill and tap a couple of holes in the frame to be able to clamp the electrical cable down, so it's not able to be snagged by brush or your foot. I ended up buying the cheaper extra battery because in haste , I didn't review the options close enough. Its not even worth trying to exchange it because of the return policies. I think that selection process could be a little more easier to understand if it were more obvious that there are two options of battery quality. I'm happy with the outcome, and know I have plenty of battery power to get me around before I have to charge everything back up. I use mine for better fishing access and exploration when camping, i don't use the extra battery a lot for just doing errands and exercise trips, the main one ( 17 AH ) does fine for that.