How To Measure Parasitic Battery Drain. The most correct method of measuring the parasitic drain is by using ammeter which is a current measuring device that measures the current flow in units called amperes. I prefer to tell you how to use a clamp meter to troubleshoot Parasitic battery drain today.
Remove the positive cable and connect the positive probe of the tester in its place. Connect the black wire to the com common ground input and plug the red wire into the highest amp input usually 20A. Fuses are removed and replaced to find the problem circuit.
By doing it this way the negative cable always remains connected to the ground in.
In electrical and electronics engineering there are two common ways of measuring current. Carefully remove the negative battery. With the key out of the ignition let the vehicle sit for 15-45-mins to allow time for all computers to enter sleep mode. Check all fuses to be sure you located each circuit causing the parasitic draw.
