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.

How to perform the test

View connection guidance notes.

  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.

The vehicle must achieve full electrical shut down, with all openings to register as closed with the Body Control Module (BCM), the alarm activated, the emote keys out of range and aftermarket accessories set as per the customer's usual use.

Example waveform

Waveform notes

This known good waveform has the following characteristics:

  • 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.

Further guidance

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

GT783

Disclaimer

Suitable accessories

  • 30 A (low amps) current clamp

    £259.00

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Guided test: Parasitic drain test - battery