BATTERY EXCHANGE TIMING MONITOR FOR UNMANNED TRUCK

PURPOSE:To enable the execution of exchange early and accurately while preventing malfunctioning of a control circuit by memorizing drop in the battery voltage during the running to judge on the necessity of exchange at a desired time based on the memory contents. CONSTITUTION:As the capacity of a battery 1 lowers, the voltage VB varies with changes of an unmanned truck, stoppage, running and stoppage, and as a result, when the voltage VB is down below a reference voltage VR with increase in the load current during acceleration, a comparator 82 sends the L level to set an FF83 and the drop in the battery voltage is stored. Then, as a certain time elapses after the unmanned truck runs at a constant speed, a CPU21 reads the memory contents of the FF83 to give a warning. Thereafter, an exchange necessity mode is set to execute an exchange operation program preferentially. Thus, the battery is exchanged when the capacity thereof lowers.