If you suspect that the 12-volt battery in your Seat Leon is damaged, weak, or defective, have it thoroughly tested and checked by a qualified specialized workshop.

Charging the 12-volt battery

Always contact a professional specialist workshop when the 12-volt battery needs to be recharged, because the specific original equipment battery model fitted at the factory utilizes advanced charging technology that requires controlled, limited-voltage charging procedures.

SEAT recommends visiting an authorized SEAT dealership or service partner for professional battery charging.

Replacing the 12-volt battery

The 12-volt vehicle battery installed in your Seat Leon has been engineered specifically to suit its designated mounting location and incorporates special factory safety features.

If the 12-volt battery ever requires replacement, the new battery must be installed by a certified qualified technician. SEAT recommends visiting an authorized SEAT dealership for this service. Detailed technical component information regarding physical size, maintenance requirements, electrical power output, and required safety characteristics can be obtained directly from a qualified technician, who possesses the necessary documentation and specialized workshop equipment.

SEAT recommends visiting a SEAT dealership to ensure correct installation.

The integrated degassing vent hole of the 12-volt battery must always be positioned and connected on the side of the negative terminal pole. Conversely, the degassing hole located on the side of the positive pole must always be securely sealed and plugged.

You must exclusively use maintenance-free 12-volt batteries that fully comply with the rigorous TL 825 06 and VW 7 50 73 manufacturing standards. These regulatory standards must bear a publication date of October 2014 or later.

The 12-volt battery must always be replaced by a qualified technician, because the onboard electronic management system of your Seat Leon must also be digitally adapted and adjusted as an essential part of the replacement process. Furthermore, exact battery parameters relating to long-term operational safety and energy management can only be properly configured using compatible diagnostic equipment. Only a qualified technician has access to both the right technology to execute this adjustment and the correct factory-approved replacement batteries.

NOTICE The use of replacement batteries that fail to meet SEAT's strict quality specifications, or batteries featuring an electrical capacity lower than that fitted as standard, could—depending on local legal regulations in each country—lead to the loss of vehicle type approval or corresponding administrative operating permits for your Seat Leon. In addition, using unapproved batteries poses a serious operational and safety risk.

Vehicles equipped with the automated Start-Stop efficiency function are fitted with a specialized, heavy-duty battery type.

Therefore, such a battery must only ever be replaced with an identical replacement battery matching the exact same factory specifications.

Disconnecting the 12-volt battery

If the 12-volt battery needs to be temporarily disconnected from the vehicle's electrical network, please observe and note the following mandatory steps:

• Switch off all active electrical consumers and accessories completely.
• Before disconnecting the battery cables, ensure that the vehicle is fully unlocked; otherwise, the factory anti-theft alarm system will be triggered immediately.
• Always disconnect the negative (-) cable first, followed by the positive (+) cable.

Connecting the 12-volt battery

• Switch off all electrical consumers prior to reconnecting the 12-volt battery to the circuit.
• Always reconnect the positive (+) cable first, followed by the negative (-) cable.

After reconnecting the 12-volt battery and switching on the ignition of your Seat Leon, several instrument cluster control lamps may briefly light up. These indicator lamps will automatically go out after driving a short distance at a speed of approximately 15 to 20 km/h (10 to 12 mph). If any of the warning lights fail to extinguish during this drive, visit a qualified specialist workshop promptly to have the vehicle electrical system checked.

If the 12-volt battery has been disconnected from the vehicle for an extended period of time, it is likely that the next scheduled maintenance service will not be calculated or displayed correctly by the on-board computer. In this scenario, you will need to manually monitor and take into account the vehicle's maximum permitted maintenance intervals.

For vehicles equipped with the "Keyless Access" locking system: If the ignition cannot be switched on immediately after reconnecting the 12-volt battery, lock and unlock your Seat Leon from the outside using the key fob. Then, attempt to switch on the ignition once more. If the ignition still fails to activate, seek professional technical assistance.

WARNING Attaching the 12-volt battery incorrectly or installing unsuitable replacement batteries may result in dangerous electrical short circuits, fire hazards, and serious personal injuries.

• Always use exclusively maintenance-free 12-volt batteries featuring an anti-spill system, with identical physical properties, technical specifications, and housing dimensions as the original factory-fitted battery in your Seat Leon.

WARNING The process of charging a 12-volt battery generates a highly volatile and explosive mixture of detonating hydrogen gases.

• Only ever charge the 12-volt battery in a thoroughly ventilated area or outdoor space.
• Never attempt to charge a 12-volt battery that is currently frozen or has recently thawed out. When deeply discharged, a battery can freeze solid at temperatures hovering close to 0ºC (+32ºF).
• If a 12-volt battery has frozen, it must be replaced immediately without exception.
• A dangerous short circuit can occur if the booster or connection wires are incorrectly attached to the battery terminals. Always connect the positive (+) cable first, followed strictly by the negative (-) cable.

NOTICE

• Never connect or disconnect the 12-volt battery when the ignition is switched on or while the engine is running. Furthermore, never use a replacement 12-volt battery that fails to meet your Seat Leon exact factory battery specifications. Doing so can cause permanent damage to the sensitive on-board electrical network or electronic control units, leading to severe electrical malfunctions.
• Never connect external power-supplying accessories—such as solar panels, trickle chargers, or aftermarket battery chargers—directly into the 12-volt interior accessory sockets to charge the vehicle's 12-volt battery. This practice can overload and severely damage the vehicle's electrical charging architecture.

For the sake of the environment

• Vehicle batteries contain hazardous, toxic substances, such as corrosive sulphuric acid and heavy lead components. Always dispose of used 12-volt batteries strictly in accordance with applicable local environmental protection regulations.
• Battery electrolyte fluid is capable of severely contaminating the surrounding ecosystem.

  If any battery fluid or operating liquid leaks out unexpectedly, absorb and collect it safely using neutralizing material, and dispose of it properly in an environmentally friendly manner.