Measuring Parasitic Drain In A Car Battery

https://www.picoauto.com/library/automotive-guided-tests/parasitic-drain/

A PicoScope is an ideal device to perform this test, plus a

few suitable accessories.

This test evaluates the level of parasitic current draw

from the battery during a vehicle's shutdown phase and sleep periods.

To obtain the correct parasitic drain values it is essential to

make sure that the vehicle
battery is serviceable and fully charged with all accessories

switched off. The vehicle
must be locked (security systems armed), and for keyless

and Smart Entry System (SES)
vehicles make sure that all keys are out of the detection range

of the vehicle.

For example, location devices, data loggers, motion cameras,

entertainment accessories,
in-car chargers and additional anti-theft devices; all of which

may consume current and
contribute to parasitic drain levels.

1. 1. Switch on the current clamp and let it warm up
      internally while it acclimatizes to the workshop
      temperature (approximately 10 minutes)
   
   
   2. Make sure that all doors and windows are closed
      and that the vehicle battery remains accessible.
      • Where the vehicle battery is located
        inside the engine bay, make sure that
        the bonnet latch is closed and that the
        bonnet position switch is set to the closed
        position with the bonnet raised. Where
        the vehicle battery is located inside the
        luggage bay, make sure that the luggage
        door latch is closed and the luggage door
        position switch is set to the closed position
        with the luggage door open. (It is important
        that the body control system recognizes that
        these panels are closed in order to commence
        the shutdown of the vehicle networks.)
   
   
   3. Make sure that the ignition is switched off.
      • In the case of a vehicle with a keyless or SES,
        lock the vehicle with the key fob/set and place
        the keys out of range of the vehicle (two meters
        minimum distance between the vehicle key set
        and the vehicle). These vehicles have the ability
        to detect the presence of the keys in the area
        around the vehicle, preventing full shutdown of
        the network.
   
    
2. Connect the test lead to Channel A on the scope.


3. Connect the coloured end of the test lead to the battery’s positive
   terminal and the black ground lead to the battery’s negative terminal.


4. Connect the current clamp to Channel B.


5. Run PicoScope Automotive by clicking the Go button or pressing the
   space bar on your keyboard.


6. Zero the current clamp and connect it around the battery negative lead
   (note the orientation of the current clamp in relation to the current flow).


7. Let the scope capture sufficient data to confirm the shutdown period and
   sleep mode of the vehicle (up to 45 minutes). Here, you will measure the
   parasitic current drain, looking for a target value of less than 80 mA after
   45 minutes.


8. Press the Stop button in PicoScope to stop the capture.

https://www.picoauto.com/library/automotive-guided-tests/parasitic-drain/