Tudor TK131 Auxiliar · Auxiliary battery 13Ah 200A AGM

Yes. AGM (Absorbent Glass Mat) technology, 13 Ah and 12 V: sealed lead-acid, with the electrolyte held in glass fibre. It tolerates heat better and handles more cycles than a conventional battery, which is why it is the required technology with advanced Start-Stop and regenerative braking.

Yes, the AGM technology of the TK131 is built for Start-Stop. AGM batteries support advanced Start-Stop and regenerative braking thanks to their higher cycle count. Basic Start-Stop: EFB. Start-Stop with regenerative braking: AGM, which withstands more cycles. Check the handbook for the technology the car manufacturer requires. It works once fitted; on most modern cars, registering it via OBD is advisable so the alternator applies the optimum charging profile.

There is no exact figure: for a battery such as the Tudor TK131 (AGM), a reasonable guide is 5 to 8 years in mild-climate car use with Start-Stop. Many factors play a part: how it is used (lots of short trips, for example), temperature (cold makes every start harder and intense heat evaporates the electrolyte), the condition of the alternator and charging system, power drawn with the engine off and maintenance, as well as the type of car and whether it has Start-Stop.

Its dimensions are 150×90×145 mm, also written 150x90x145 mm; the height already includes the terminals. Check the room available in your car, because a single millimetre too much can stop the clamp from closing.

It has the positive on the left (polarity). Put it in front of you, terminals towards you: the post with the red ring and the + sign is the positive. Compare it with the battery you are replacing: if it does not match, cables must be lengthened or the system reconfigured, with a risk of short circuit.

For your own vehicle: type your number plate into the finder (DGT/DVLA/KBA identify model and engine), check the "Compatible vehicles" tab below, listing vehicles verified by our technical team, or message us on WhatsApp with make, model, engine and year; we reply during business hours (Mon–Fri 10:00–13:30 and 16:30–18:00 (Spanish time, CET)). Always cross-check with what the car manufacturer states in the owner's handbook.

A direct equivalent needs what this TK131 offers: 150×90×145 mm, positive on the left, the same Ah and CCA and AGM technology. Not just any technology will do: an EFB cannot be replaced with a conventional battery in Start-Stop cars. The "Equivalents" section further down lists the recommended alternatives.

The Varta alternative that fits where the TK131 goes, with the same polarity. Compared with the TK131 it has the same Ah and cranking power. It costs 6,60 € more. A straight swap with nothing to adapt; the difference is the price and the brand you prefer.

Same case and same fitting as the TK131, from Exide. Compared with the TK131 it has the same Ah and cranking power. It costs 1,40 € less. If you want to save or the TK131 is out of stock, it is the safe alternative: same dimensions, same polarity and official warranty.

It is the recommended choice for advanced Start-Stop with regenerative braking (BMW EfficientDynamics, Mercedes Eco, Audi MHEV, Land Rover ECO, Volvo i-Stop) and copes better than an EFB with tilting, vibration and extreme temperatures. In an AGM (Absorbent Glass Mat) battery the electrolyte is held in a glass-fibre mat: no spills, and many more charge/discharge cycles than a conventional battery. Cold cranking current (EN) of the Tudor TK131: 200 A.

Advisable, yes; essential, on most cars, no. Registering it via OBD makes the alternator charge with the optimum profile from the first minute and extends battery life, which matters most on brands with sophisticated BMS such as BMW, Mercedes, Audi, Volvo or Land Rover. A workshop only needs an OBD scanner and a few minutes. DIY apps: VCDS / Carista (VAG), Bimmercode (BMW), iCarsoft. Even if you do not register the Tudor TK131, the car will start correctly; the profile adjusts within a few days.