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.