Once the battery, starting and charging systems are all tested attention should turn to battery drain and parasitic current draw, explains Pico Technology.
Parasitic drain demands a prolonged test, 30 minutes is not uncommon for a modern vehicle to shut down and move to sleep mode.
If the vehicle has a history of battery discharge, you may choose to monitor the parasitic drain overnight or even a number of days. This itself presents a challenge surrounding current clamps.
In a recent statement Steve Smith of Pico Technology said: “Given our Pico current clamps are powered by an internal battery with a continuous operational time ranging from 14 to 16 hours, we most certainly run the risk of erroneous results during prolonged parasitic tests.
“I think it is worth mentioning here how a current clamp operates in relation to the values we capture on our scope screen.
“The current flow through a conductor has the valuable side effect of producing a magnetic field about the conductor.
“By closing the jaws of our current clamp around the conductor the magnetic field can be detected and converted into a voltage directly proportional to the strength of the magnetic field.
“The voltage is then sent to the scope and displayed on screen as a current value.
“Prior to connecting the clamp around the conductor a zero operation is carried out to ensure accurate display of current values and a true zero point reference.
“This is achieved by pressing the zero button on the clamp, which charges a capacitor within the clamp removing any DC offset value.”
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