Electric motors were sometimes thought to be less efficient than the reliable internal combustion engines in the early years of electric vehicles. However, they did make up for this with their instant torque and, of course, zero emissions. Modern battery technology and the rising popularity of quick charging facilities have made EVs more common, with some people ditching their gas-powered two and four-wheelers in favor of fully electric ones.
An issue that oftentimes plagues electric motors, however, is that they often see significant drops in performance as battery level drains, or when the motor gets increasingly hot. This is the case not only for EVs, but for battery-powered devices in general. I'm sure those of you with battery-powered drills or even RC cars will have noticed the motors spin a lot slower when battery levels have dropped, or after using your gadgets for a prolonged period of time. Naturally, in an EV setting, this could have some serious drawbacks, as we generally want our bikes and cars performing at their best regardless of the battery's state of charge.
