China's urban environmental pollution has reached a very serious point, especially in some big cities, air pollution is the most important, the current impact on the urban environment is the most significant vehicle exhaust, automobile exhaust is a difficult to be decomposed, easy to be absorbed by our human body a harmful substance, we plant a large number of trees, is for our survival environment can be better, the air can be cleaner, now the country is advocating energy-saving emission reduction, green travel, for our survival environment each of us should do their own strength. The advent of the tricycle for our daily travel to provide a more convenient service, but also for our living environment to create a green pollution-free driving. The performance of the Tricycle is determined by the battery. The driving distance is determined by the battery energy density, and the acceleration performance is determined by the power density. In addition, the power of his weight, cost accounted for the whole vehicle proportion is an important component of cost analysis. If you say that the maintenance of the Tricycle electric vehicle is the battery maintenance is not too. Therefore, the battery of the Tricycle electric vehicle has the energy density, the qualified use boming, the reliability, the safety, the easy maintenance and the low cost performance which can support the mileage. Although the Tricycle electric vehicle has incomparable advantages, it still has some shortcomings, besides some social reasons, there are some technical problems, so far, it has not been solved well. Mainly: 1, a charge to continue the mileage is too short. This is mainly due to the failure of battery research to make breakthrough progress. The cost of the tricycle is too high. This is mainly caused by three reasons: 2, the battery is lower than the energy, it has to install a large number of batteries to achieve the required mileage; the output of the motor and the regulator is high; the battery has a short cycle life and high replacement rate. Battery charge time is long, usually need 6-10h to complete, bring inconvenience to the user. The development of subsidiary bodies is slow. Because the tricycle has no idle speed, it cannot use the auxiliary mechanism such as the air degeneracy and power steering of the fuel vehicle. In addition, the development of the auxiliary mechanism of electric vehicles, such as residual power measurement, is late.