A:Answer Book says it can handle a 20% grade. I just went up a steep hill, probably 30%, and I am near the weight limit, and it slowed to a crawl near the top. This is about 150 yards long uphill. Doing this, I would guess, took about 4 miles off the total miles for a 95% charge. I was doing 18 mph and set at "sport." Pretty good performance I would say.