Several methods for measuring and monitoring temperature have been presented for systems requiring temperature monitoring. In one implementation, the system has been applied to battery assemblies. Temperature measurements for every part of the battery assembly are disclosed. In one aspect the surface temperature of a battery assembly is measured. In another aspect, the internal temperature of the battery assembly is measured. In other aspects, the internal and external temperatures of several battery assemblies are measured. Based on the measured temperature, control signals are generated by a control system to switch down the power of the battery charging system so as to prevent excess heat generation.