Nuclear power is playing an important role in energy supply in modern society. The safety of nuclear power plant is thus an important issue. Due to the harmful effects of radiation to human body, robots are used when and where the radiation level in the plant is high. Thus study of the radiation effects on robots, especially on the critical components of robots becomes an urgent issue. In this paper, we investigate the impact of the radiated lithium-ion battery to mobile robots. Mobile robots especially visual tracking guided robot can be used to perform multiple tasks in a nuclear environment. Under radiation, the lithium-ion battery will degrade in terms of capacity, which means if the battery is used as a normal battery, the mobile robot will not perform satisfactorily. We first present the result on the battery degradation due to radiation. Then we study the impact to the robot if it is powered by a radiated battery. The performance of the robot is evaluated under two different conditions, before and after the radiation, and by three different experiments. The radiation effects on the robot performance are shown and analyzed.