WHAT IS PARASITIC LOAD?
Parasitic (key off) is the cumulative load produced by electrical devices, for example, clocks, computers, alarms, etc., that operate after the engine is stopped. Parasitic loads typically run 20 to 120 milliamps. To test the parasitic load, an ammeter should be inserted in series with the negative battery cable without the engine running. If the parasitic load is prematurely discharging your battery, start removing fuses one-at-a-time until the offending electrical component is identified. Glove box, trunk, and under hood lights that do not automatically turn off are the most common offenders. Leaving your headlights on will generally discharge a fully charged battery (with 90 minutes of Reserve Capacity) within a couple hours.
