Battery No-Load Voltage - Vehicles Without Energy Management Control Module J644, Checking
Battery No-load Voltage - Vehicles Without Energy Management Control Module J644, Checking
NOTE: Measuring the no-load voltage, e.g. within the prescribed maintenance and service work on vehicles in storage, determines if the battery must be recharged Maintenance Tables.
Special tools, testers and auxiliary items required
- Multimeter VAG 1526C, Multimeter Fluke 83 or equivalent (VAG tester illustrated here for reference only).
To ensure correct measurements, follow prerequisites and procedure exactly as given:
Prerequisites
- If no-load voltage on battery installed in vehicle is measured, disconnect ground cable.
- Battery must not be discharged by electrical consumers within 2 hours prior to measurement.
- Battery must not be charged within 12 hours prior to measurement.
- Battery temperature must be at least -10 degrees C.
Procedure
- Disconnect battery ground cable.
After a holding time of at least 12 hours:
- Use multimeter to measure voltage between battery terminals.
- Specified value: 12.5 Volts or above = Battery OK.
- If no-load voltage is under 12.5 Volts, charge battery.
- After charging for 5 minutes, perform load test .
- If battery no-load voltage is below 11.7 Volts, battery is severely discharged.
- If no-load voltage is OK, reconnect battery.
- Follow measures required after reconnecting battery.