Electrical · Expert tip
Test charging in the right order
Off, idle, under load — in that order.
The expert tip
- Engine off: battery state (12.4–12.7 V)
- Idle: charging voltage (13.8–14.6 V)
- With loads: stays above 13.2 V
- A weak battery can mask a bad alternator
Source: Charging system experts
Apply tips that match your car and manual. For anything safety-critical or high-voltage, use a qualified mechanic.