Flat battery after two days parked
- Make and model
- Opel Astra H
- Year
- 2008
- Engine
- 1.6 16V
- Fuel
- Petrol
- Mileage
- 175,000 km
Customer complaint
The battery goes flat if the car stands for two days. A new battery was fitted three months ago and the charging voltage is normal.
ParkedIntermittent
Fault codes
No fault codes stored.
Measurements and live data
| Parameter / measurement | Measured | Expected |
|---|---|---|
| Parasitic drain after the modules went to sleep | 420 mA | below about 50 mA |
| Charging voltage at 2,000 rpm | 14.3 V | 13.8–14.7 V |
Tests performed
- Drain measured with a clamp meter after 40 minutes420 mA, steady
- Voltage drop across each fuse with the fuse box openClear drop only across the fuse feeding the interior and glovebox lights
- Circuit checkedGlovebox light switch stuck, lamp on with the lid closed
Solution
Root cause
Glovebox light switch stuck closed, keeping the lamp on with the lid shut.
Repair
Replaced the glovebox light switch. Drain after sleep now 22 mA. Battery recharged and tested.
Parts
Glovebox light switch
Labour time
1 h
Lesson learned
Measure the voltage drop across fuses instead of pulling them: pulling a fuse wakes modules and restarts the sleep timer.
Training case: the usual fix for this fault, not a confirmed repair on a specific car.
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