Parasitic drain test – battery

The purpose of this test is to evaluate the level of parasitic current draw from the battery during a vehicle's shutdown phase and sleep periods.

Connection guidance

Connection for diagnostic work will vary dependent on application.

Technicians should whenever possible gain access to the test circuit without damage to seals and insulation. If this is not possible then make sure appropriate repairs are completed.

Parasitic drain test pre-requisites;

Vehicle must achieve full electrical shut down;

  • All openings to register as closed with Body Control Module (BCM)
  • Alarm activated
  • Remote keys out of range
  • Aftermarket accessories set as customers usual use

Ensure the test equipment is able to function for an extended time period e.g. current clamp battery condition, scope and pc power supply.

How to perform the test

  1. Connect PicoScope Channel A. across the battery terminals.
  2. Connect the low amp clamp to PicoScope Channel B select the 20 A scale and zero the clamp.
  3. Wait around 10 minutes for the current clamp to acclimatise to test conditions (temperature), then connect around the battery earth lead.
  4. Minimize the help page. You will see that PicoScope has displayed an example waveform and is preset to capture your waveform.
  5. Start the scope to see live data.
  6. Some vehicles may take around 45 minutes to completely close down all electrical systems. (You may need to test for longer periods, e.g. Over-night to acquire sufficient test data).
  7. With your waveforms on screen stop the scope.
  8. Apply a Lowpass Filter to clean the Channel B waveform.
  9. Use the Waveform Buffer, Zoom and Measurements tools to examine your waveform.

Note

Ensure the test equipment is able to function for an extended time period e.g. current clamp battery condition, scope and pc power supply.

Example waveform

Waveform notes

Further guidance

Refer to vehicle technical data for specific test conditions and results.

The battery voltage should remain stable and between 12.4 V and 12.8 V throughout the test. The current draw from the battery during the shutdown period of the vehicle networks and accessories is 228 mA for over 6 minutes. The shutdown periods can range from 30 minutes to 2 hours (depending on manufacturer). The current draw will also vary depending on network and system activity. You can clearly see a reduction in current draw from the battery as the networks begin to sleep and the parasitic current draw from the battery as it settles at 40 mA for over 21 minutes (sleep mode). The target parasitic drain is < 80 mA and stable throughout. It is clear on the waveform when the networks wake up, responding to the activation of the key fob/set. The vehicle is now unlocked and the networks are awake.

GT783-2

Disclaimer
This help topic is subject to changes without notification. The information within is carefully checked and considered to be correct. This information is an example of our investigations and findings and is not a definitive procedure. Pico Technology accepts no responsibility for inaccuracies. Each vehicle may be different and require unique test settings.

Suitable accessories

  • 30 A (low amps) current clamp

    £259.00

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Guided test: Parasitic drain test - battery