Varta AUX1 · Car battery 12V 35Ah 520A

Varta AUX1 Dynamic AUX (formerly Silver Dynamic Aux) 35Ah 520A 12V Car Battery

The Varta AUX1 car battery is the 12 V, 35 Ah and 520 A cold cranking (EN) model from Varta's Dynamic AUX (formerly Silver Dynamic Aux) range, designed to work as an auxiliary battery in cars with advanced Start-Stop and a great deal of electronics. It replaces the original battery in cars with the 212 × 175 × 140 mm format without any modifications: the same 35 Ah capacity and the same terminal layout (positive on the right).

• Specific replacement for the backup battery fitted to the car at the factory.
• Supports the advanced Start-Stop system without voltage drops.
• AGM technology: maintenance-free and resistant to cycling.
• Auxiliary battery: it powers the vehicle's comfort and safety electronics.

Vehicles compatible with the Varta AUX1 battery

The Varta AUX1 is compatible with more than 9 vehicles: it is fitted as standard or as a replacement by brands such as Mercedes-Benz and Volvo. If you are looking for a battery for Mercedes-Benz or Volvo with these dimensions, the AUX1 is one of the usual replacement references. Not sure whether it is the right one for your car? Check in seconds by entering your registration number in our finder.

Format and fitting of the Varta AUX1

Its external dimensions are 212 × 175 × 140 mm and it weighs 10,75 kg. The positive terminal on the right determines which side the cables end up on: it is the detail that causes the most purchasing mistakes, so it is worth checking before ordering. It uses a B13 hold-down, the system that secures it to the vehicle's battery tray. Checking the three dimensions and the terminal positions before buying avoids the most common mistake when replacing a battery.

The Varta AUX1 and the Dynamic AUX range

The Dynamic AUX range brings together Varta's auxiliary batteries: these are not the main starter battery but the one that powers secondary functions (advanced Start-Stop, safety and comfort systems) in premium cars.

It is installed alongside the main battery and prevents voltage drops in the auxiliary electronics. It is worth establishing clearly whether your car needs this backup battery in addition to the starter one.

This series uses lead-acid technology with plates optimised for a good balance between cranking power and service life. It is the natural substitute when your car does not have Start-Stop and came with a standard battery as original equipment: the same philosophy, without paying over the odds for a chemistry you do not need. This battery used to belong to Varta's Silver Dynamic Aux range; following the brand's commercial renaming (2025), it forms part of the new Dynamic AUX series.

Why choose a Varta battery

Varta is a byword for reliability: original equipment in numerous European vehicles and one of the most proven brands on the market. Replacing your battery with a Varta restores OEM quality — the same performance as the factory-fitted unit — with the manufacturer's backing.

Behind Varta is Clarios, one of the largest manufacturers of starter batteries in the world and a supplier to the assembly lines of numerous car brands. That German engineering heritage translates into reliable starting year after year.

Varta is Europe's leading manufacturer of starter batteries: its production volume and quality controls guarantee consistent reliability batch after batch, something own-brand labels cannot always assure.

Manufacturer's warranty

The Varta AUX1 battery comes with the official manufacturer warranty.

Care and maintenance

To get the most out of it, keep the alternator in good order and avoid leaving lights or accessories on with the engine switched off. Repeated very short journeys are its main enemy: they stop the battery from recharging fully and shorten its life. If the car is going to stand unused for weeks, it is worth disconnecting a terminal or using a trickle charger so it does not discharge below the safe threshold. Checking that the terminals are clean and properly tightened also helps ensure reliable starting.