The Focus Jam2 e-mountain bike has two batteries, one built into the down tube behind the front wheel and another that can be locked onto the outside of the down tube. If you're going on a shorter trip, you only need one. The internal one can be replaced by removing the motor -- a complicated operation most likely done by a shop.
The Sea Otter Classic e-mountain bike race made four 2.9-mile loops over the hills of the Mazda Raceway Laguna Seca near Monterey, California. Much of the course was the same as that ridden by pros on the cross-country race with conventional mountain bikes.
E-mountain bikes in races are limited to models that amplify your pedal stroke -- no throttles allowed -- and whose motors cut out once you're going faster than 20mph. This racer was disqualified because his bike had a more powerful motor.
Pro bike racer Ben Goyette, a video game programmer by day, was at the Sea Otter Classic to race his conventional mountain bike. But he's fine with e-mountain bikes, and says riding them is like a really good day on a conventional bike.