An overnight discharge requires separate proof of battery capacity, charging performance, and key-off current after the vehicle has entered sleep mode.
Why this matters
Modern modules may remain awake for many minutes. Opening a door, moving a key, or interrupting current can restart the timer and create misleading results.
Evidence to capture first
- Battery open-circuit voltage and a valid capacity or conductance result
- Charging voltage and voltage drop under meaningful load
- Key-off current plotted from shutdown through the expected sleep period
A disciplined path
- Stabilize and test the battery first; a damaged battery can mimic a draw.
- Prepare door and hood latches before connecting the measurement setup.
- Use a fused method that will not route starter current through a small meter.
- When excessive current remains after sleep, isolate branches using voltage drop across fuses or an approved current-clamp method.
Decision point
The suspect branch is the one whose measured current contribution matches the excess. Pulling random fuses before the vehicle sleeps can create new wake-up events.
Source desk
Use current model-specific service information for specifications, connector locations, disabling procedures, and tightening values. The following public resources support the broader safety or system context used in this guide.
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