CONCORDE AIRCRAFT BATTERY PARASITIC LOAD TESTER

A parasitic load is a small, continuous flow of DC current that takes power from the battery when the master switch is off. Parasitic loads are present in most modern aircraft to some degree. Examples of parasitic loads are relays, clocks, radios and on-board computers. Depending on the magnitude of the parasitic load, the battery in an inactive aircraft may be depleted within weeks or even days. A battery discharged in this manner can cause an AOG event. Another inherent danger is that a battery without enough emergency power reserve can often still start the engine(s) leaving you vulnerable in the case of a generator failure. The FAA requires aircraft batteries to be certified with a minimum of 80% capacity for emergency power reserve in the event of an electrical generating system failure.

Measuring parasitic load is easy to do by connecting the PLTA between the battery receptacle and the aircraft mating plug. The PLTA is a molded polypropylene body equipped with separate test leads for connection to a digital multimeter (DMM). It is rated for loads up to 10 amperes and is equipped with a 10 amp fuse.