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.
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.
Note: additional accessories, which are not visible, may have been installed.
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.
Contact the vehicle owner for clarification on any of the above installations.
Alternative current clamp:
TA018 20/60 A DC (low amps) current clamp – see Modification notes below.
Lowpass filtering is incorporated into the PicoScope software and can be applied to any channel to remove high frequency noise and reveal the true signal level beneath.
A 1 Hz lowpass filter applied to any signal will reject all frequency signals above 1 Hz. Only signal values of 1 Hz and below will pass through and be displayed.
To activate/deactivate the lowpass filtering feature:
Click anywhere on the scope grid to exit the channel options menu.
Alternatively, the TA018 20/60 A current clamp (small jaw) can be used on channel B. However, before you make any measurements with PicoScope, you need to make sure that the opening of the TA018 current clamp jaw is wide enough to connect around the battery negative cable. Where the diameter of the battery lead exceeds 8 mm, you will need to insert a 10 A fused jumper wire between the battery's negative terminal and the battery lead (see image).
In order to simulate the shutdown scenario of the vehicle it is essential that the battery negative terminal remains connected to the chassis via the fused jumper lead. If the battery lead is disconnected, the battery will reboot on-board computers preventing accurate and realistic parasitic drain results.
To avoid momentary disconnection of the battery (and excessive current draw), insert the fused jumper wire by following the procedure listed below:
Note: Once the test is complete, re-establish a partial connection between the negative battery terminal and battery lead (as in Fig 2 above). Once partial connection is complete, remove the fused jumper wire, press the battery clamp down to seat it correctly, and tighten securely.
All values included in the example waveforms are typical and not specific to all vehicle types.
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.
You can read more about Parasitic drain testing in the online training section on our website.
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.
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