12 V vehicle battery
Introduction
The 12-volt vehicle battery is a component of the electrical system and serves to supply energy to the vehicle. During maintenance procedures, the 12 V vehicle battery is checked and replaced if necessary.
You may only perform procedures on the electrical system yourself if you are familiar with the necessary procedures and the general safety precautions, and if the correct equipment and operating fluids and suitable tools are available. Work performed incorrectly can result in serious injuries ⇒ 
. Have all work performed by suitably qualified professionals. Volkswagen recommends contacting an authorized Volkswagen dealer or authorized Volkswagen Service Facility.
Information about warning and indicator lights can be found in the troubleshooting section at the end of the chapter ⇒ Troubleshooting.
Battery switch-off in an accident with triggering of the airbag
In vehicles with a 12 V vehicle battery in their vehicle interior or luggage compartment, the electrical connection to the 12 V vehicle battery is pyrotechnically disconnected in an accident with airbag deployment. This prevents a short circuit. You can find information on the installation location of the battery in the section on checking the acid level of the 12 V vehicle battery ⇒ Checking the 12 V vehicle battery acid level.
Detailed warnings for the 12 V vehicle battery
Always wear eye protection.
Battery acid is highly corrosive. Always wear protective gloves and eye protection.
Fire, sparks, open flame, and smoking are forbidden.
A highly explosive mixture of gases forms when charging the 12 V vehicle battery.
Always keep children away from battery acid and the 12 V vehicle battery.
Always heed the Owner's Manual.
WARNING
Performing work on the 12 V vehicle battery and the electrical system can cause serious injuries, fires, or electric shocks. Always read and heed the following warnings and safety precautions before performing any procedures:
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Before performing any work on the 12 V vehicle battery, switch off the ignition and all electrical equipment and disconnect the 12 V battery negative cable.
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Always keep children away from battery electrolyte and the 12 V vehicle battery.
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Always wear eye protection and safety gloves.
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Battery acid is highly corrosive. It can burn skin and cause blindness. When handling 12 V vehicle batteries, always protect your hands, arms, and face from spraying battery acid.
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Do not smoke while working and never work near open flames or sparks.
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Avoid creating sparks when working with wires and electrical equipment or when discharging static electricity.
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Never short circuit the battery terminals.
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Never use a damaged 12 V vehicle battery. The 12 V vehicle battery may explode. Replace a damaged 12 V vehicle battery immediately.
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Never use a frozen 12 V vehicle battery. A drained 12 V vehicle battery can freeze at temperatures around 32 °F (0 °C). Replace the 12 V vehicle battery immediately.
WARNING
California Proposition 65 Warning
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This product can expose you to chemicals including lead and lead components, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.
NOTICE
UV rays can damage the battery housing.
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Do not expose the 12 V vehicle battery to direct sunlight for a long period of time.
NOTICE
The 12 V vehicle battery could “freeze” and be destroyed.
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Protect the 12 V vehicle battery against freezing temperatures if the vehicle is parked for long periods of time.
After starting the engine when the 12-volt vehicle battery is severely drained or when it has been replaced or jump-started, the system settings (time, date, personal convenience settings, and programming) and user profiles may be changed or erased. Check and correct the settings after the 12 V vehicle battery is sufficiently recharged.
Checking the 12 V vehicle battery acid level
Please read the introductory information and heed the Warnings and Notice ⇒ and
Safety precautions for working in the engine compartment.
Check the acid level of the 12 V vehicle battery regularly if mileage is high, in countries with warm climates, or if the 12 V vehicle battery is old. Otherwise, the 12 V vehicle battery is maintenance-free.
12 V vehicle battery location
The 12 V vehicle battery is located in the engine compartment.
Preparations
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Prepare the vehicle for work in the engine compartment ⇒ In the engine compartment.
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Open the hood
⇒ Opening and closing the hood.
Check the battery acid status for vehicles with a 12 V vehicle battery in the engine compartment
WARNING
Performing work on the 12 V vehicle battery can cause serious injuries, explosions, or electric shocks.
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Always wear eye protection and safety gloves.
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Never use open flames or smoldering objects to provide lighting.
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Battery acid is highly corrosive. It can burn skin and cause blindness. When handling 12 V vehicle batteries, always protect your hands, arms, and face from spraying battery acid.
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Never open a 12 V vehicle battery.
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Never tilt the 12 V vehicle battery. Acid can leak out of the vent openings and can cause chemical burns.
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If battery acid comes into contact with the skin or eyes, rinse the affected area immediately with cold water for several minutes. Then consult a doctor immediately.
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Consult a doctor immediately if battery acid is swallowed.
Depending on the vehicle equipment, an additional bracket must be removed to see the viewing window. An additional tool that is not available in the vehicle tool kit is required to do this. Always have the acid level of the 12 V vehicle battery checked by an authorized Volkswagen dealer or authorized Volkswagen Service Facility. Volkswagen recommends contacting an authorized Volkswagen dealer or authorized Volkswagen Service Facility.
Fig. 168 Window on the top of the 12 V vehicle battery (general example).
Make sure there is enough lighting to clearly see the color indicator in the circular window on the top of the 12 V vehicle battery fig. 168.
The color indicator in the circular window changes depending on the acid level in the 12 V vehicle battery.
- Light yellow or colorless
- The 12 V vehicle battery acid level is too low. Have the 12 V vehicle battery replaced by an authorized Volkswagen dealer or authorized Volkswagen Service Facility. Volkswagen recommends contacting an authorized Volkswagen dealer or authorized Volkswagen Service Facility.
- Black
- The 12 V vehicle battery acid level is OK.
The acid level of 12 V vehicle batteries labeled 
cannot be checked for technical reasons. Suitably qualified professionals can inspect the battery. Volkswagen recommends contacting an authorized Volkswagen dealer or authorized Volkswagen Service Facility.
Charging, replacing, disconnecting, or connecting the 12 V vehicle battery
Please read the introductory information and heed the Warnings and Notice ⇒ andSafety precautions for working in the engine compartment.
If you suspect that the 12 V vehicle battery is damaged or malfunctioning, see suitably qualified professionals to have the 12 V vehicle battery checked. Volkswagen recommends contacting an authorized Volkswagen dealer or authorized Volkswagen Service Facility.
Charging the 12 V vehicle battery
The 12 V vehicle battery should be charged by suitably qualified professionals because the 12 V vehicle battery that is installed at the factory requires a charging process where the voltage is limited ⇒ . Volkswagen recommends contacting an authorized Volkswagen dealer or authorized Volkswagen Service Facility.
Replacing the 12 V vehicle battery
The 12 V vehicle battery is designed to fit the location where it is installed and is equipped with safety features. If a 12 V vehicle battery needs to be replaced, have the replacement part fitted by qualified professionals. Volkswagen recommends contacting an authorized Volkswagen dealer or authorized Volkswagen Service Facility. Check with qualified professionals to find out the component information regarding size and the required maintenance, performance, and safety features. They must possess the necessary technical documentation and equipment. Volkswagen recommends contacting an authorized Volkswagen dealer or authorized Volkswagen Service Facility. The vent opening on the 12 V vehicle battery must always be located on the negative terminal side. The vent opening on the positive terminal side must always be sealed ⇒ .
Only use a maintenance-free 12 V vehicle battery that conforms to the TL 825 06 and VW 7 50 73 standards. These standards must be from October 2014 or later.
Always have the 12 V vehicle battery replaced by qualified professionals because the vehicle electronics must be adapted as part of the replacement. Only qualified professionals have the necessary equipment to perform the adaptation and have access to the correct replacement batteries.
Disconnecting the 12 V vehicle battery
If the 12 V vehicle battery must be disconnected from the vehicle electrical system, note the following:
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Switch off all electrical consumers.
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Unlock the vehicle before disconnecting the battery. Otherwise, the anti-theft alarm system will be triggered.
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Disconnect the negative cable first, and then the positive cable ⇒
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Connecting the 12 V vehicle battery
If the 12 V vehicle battery must be connected to the vehicle electrical system, note the following:
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Switch off all electrical consumers.
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Connect the positive cable first, and then the negative cable ⇒
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Various indicator lights may turn on after connecting the 12 V vehicle battery and switching the ignition on. They will turn off after driving a short distance at a speed of approximately 10–12 mph (15–20 km/h). If the indicator lights light up and remain on, contact an authorized Volkswagen dealer or authorized Volkswagen Service Facility and have the vehicle checked. Volkswagen recommends contacting an authorized Volkswagen dealer or authorized Volkswagen Service Facility.
If the 12 V vehicle battery was disconnected for a long period of time, the next scheduled maintenance may not display correctly or it may not be calculated correctly ⇒ Service interval display. Follow the maximum permissible maintenance interval ⇒ Maintenance.
Vehicles with a starter button: If the ignition cannot be switched on after connecting the 12 V vehicle battery, carry out the following actions:
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Lock and unlock the vehicle from the outside.
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Try to switch the ignition on again ⇒ Starter button.
If the ignition will not switch on, see an authorized Volkswagen dealer or authorized Volkswagen Service Facility for assistance.
Automatic equipment deactivation
If the ignition is switched on for a very long time when the engine is off or the parking light is switched on when parking for a very long time, the intelligent power management cannot always prevent the 12 V vehicle battery from being drained.
If the 12 V vehicle battery is under a heavy load, the intelligent power management will automatically begin certain measures to prevent the 12 V vehicle battery from draining.
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The idle speed will be increased so that the alternator delivers more power.
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If necessary, equipment that uses a lot of power will have its performance limited or will be switched off.
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The power supply to the 12 V socket will be interrupted temporarily when the engine is started.
12 V vehicle battery draining
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If the vehicle is parked for long periods of time without running the engine, especially if the ignition is on.
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If electrical equipment is used when the ignition is switched off.
WARNING
Securing the vehicle battery incorrectly or using the wrong 12 V vehicle battery can cause short circuits, fires, and serious injuries.
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Always use maintenance-free and leak-proof 12 V vehicle batteries that have the same characteristics, specifications, and dimensions as the 12 V vehicle battery that was installed at the factory.
WARNING
A highly explosive mixture of hydrogen gas can form when charging the 12 V vehicle battery.
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Only charge 12 V vehicle batteries in well-ventilated areas.
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Never charge a frozen or thawed 12 V vehicle battery. A drained 12 V vehicle battery can freeze at temperatures around 32 °F (0 °C).
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Always replace the 12 V vehicle battery if it freezes.
WARNING
A highly explosive mixture of gas forms in the 12 V vehicle battery when operating the vehicle.
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For vehicles with the 12 V vehicle battery in the vehicle interior or luggage compartment, ensure that the degassing hose is connected to the 12 V vehicle battery correctly. The degassing hose must always be connected to the negative terminal side of the 12-volt vehicle battery. If there is an opening on the positive terminal side of the 12-volt vehicle battery, it must always be capped.
WARNING
Cables that are connected incorrectly can cause a short circuit.
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Connect the positive cable first and then the negative cable.
NOTICE
Never connect or disconnect the 12 V vehicle batteries when the ignition is on or the engine is running.
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The electrical system or electrical components could be damaged and electrical malfunctions could result.
NOTICE
Never connect accessories that provide power, such as solar panels or battery chargers, to the 12 V socket in order to charge the 12 V vehicle battery.
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The electrical system or electrical components could be damaged and electrical malfunctions could result.
NOTICE
Never use a 12 V vehicle battery that does not conform to the vehicle specifications.
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The electrical system or electrical components could be damaged and electrical malfunctions could result.
12 V vehicle batteries can contain toxic substances such as sulfuric acid and lead. Dispose of 12 V vehicle batteries correctly.
Battery acid can pollute the environment. Collect spilled battery acid and dispose of it correctly.
Troubleshooting
Please read the introductory information and heed the Warnings and Notice ⇒ andSafety precautions for working in the engine compartment.
12-volt power supply
The red warning light turns on. A message is shown in the instrument cluster display.
Do not continue driving! Possible failure of the electrical system.
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Stop the vehicle immediately and park it safely ⇒ Parking.
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Turn off electrical equipment that is not needed.
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Switch the ignition off.
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Contact an authorized Volkswagen dealer or authorized Volkswagen Service Facility for assistance.
When the red warning light is illuminated, the start-stop system is switched off. The start-stop system will only be automatically switched on again after the engine is restarted. ⇒ Start/Stop system.
12-volt power supply
The yellow indicator light turns on. A message is shown in the instrument cluster display.
Messages about the battery charge level of the 12 V vehicle battery.
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Let the engine run so that the 12 V vehicle battery can be recharged.
If the message about the battery charge level of the 12 V vehicle battery does not disappear after a few minutes despite the measures having been taken, then contact an authorized Volkswagen dealer or authorized Volkswagen Service Facility.
Messages about the 12 V power supply.
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Contact an authorized Volkswagen dealer or authorized Volkswagen Service Facility for assistance.
If the yellow indicator light lights up, the start-stop system will not be able to start the engine. If the yellow indicator light has turned off, the 12 V vehicle battery has a sufficient battery charge level to automatically restart the engine ⇒ Start/Stop system.
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