Batteries rarely exploded now a days and many have UL certifications. There are some that do 50 mph, some that are 100% submergible in water up to 30 minutes, some that do 100 miles without pedaling and 200 miles pedaling, and some that have power converters that convert DC into AC power with their large batteries and accept solar panels. It is only getting better and better. Pretty amazing when you think about it.