TUDOR AUXILIARY Batteries

Tudor auxiliary AGM battery: reliable back-up for your second battery

Many recent Mercedes, BMW and Audi models run two batteries: the main one handles engine starting, while the auxiliary battery keeps Start-Stop, the electric parking brake and other systems powered when the engine is off. The Tudor Auxiliary range does that job with sealed, maintenance-free AGM technology, safe to mount inside the cabin or boot with no risk of leaks.

When the auxiliary battery wears out, the dashboard usually shows an auxiliary battery malfunction warning and Start-Stop stops working, even though the car still starts normally.

Models in the Tudor Auxiliary range

• Tudor TX12 (12 Ah): auxiliary battery for Mercedes E-Class W213 and BMW 5 Series.
• Tudor TX13 (13 Ah): designed for Mercedes S-Class and BMW 7 Series.
• Tudor TX20 (20 Ah): back-up battery for 48V mild-hybrid systems.

Compatibility: choosing the right auxiliary battery

Find the exact model your car uses in our battery comparator or look it up with the battery finder by number plate. After fitting, OBD coding is mandatory so the charging management recognises the new battery.

Frequently asked questions about the Tudor Auxiliary battery

What is the difference between the main and the auxiliary battery?

The main battery cranks the engine; the Tudor Auxiliary, at 12 to 20 Ah, backs up Start-Stop and the electronics while the engine is off. They are different batteries and not interchangeable.

Does the auxiliary battery need OBD coding?

Yes. On Mercedes, BMW and Audi, OBD coding is mandatory after replacement so the energy management system applies the correct charging curve to the new battery.

Is it equivalent to the VARTA Silver Dynamic Aux?

Yes. The Tudor Auxiliary range is the direct counterpart of the VARTA Silver Dynamic Aux: same AGM technology and same applications, built in Europe by the Exide Group.

How long does an auxiliary AGM battery last?

Under normal use, an auxiliary AGM battery typically lasts 4 to 6 years. It needs no maintenance, but replace it as soon as the dashboard warns you, to avoid overworking the main battery.

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