# Auxiliary battery Tudor TK091 12V 9Ah 120A AGM ![Auxiliary battery Tudor TK091 12V 9Ah 120A AGM](https://baterias.com/962-home_default/battery-tudor-tk091-9ah-120a.jpg) > Tudor TK091 auxiliary battery 12V 9Ah 120A AGM. Start-Stop Auxiliary range. Dimensions 150×90×105 mm, + terminal on the left. Check fitment by plate. **Category:** [Auxiliary Batteries](https://baterias.com/gb/auxiliary-batteries) → [TUDOR](https://baterias.com/gb/tudor) - **Canonical URL**: https://baterias.com/gb/battery-tudor-tk091-9ah-120a - **Language**: en-GB - **Brand**: TUDOR - **Reference**: BCOM-TUDOR-TK091 - **EAN**: 3661024056557 - **MPN**: TK091 - **Price**: 61,70 € - **Stock**: In stock ## Technical specifications | Feature | Value | |---|---| | Brand | TUDOR | | Reference | TK091 | | Model | TUDOR AUXILIAR | | Voltage (V) | 12 V | | Largo | 150 mm | | Ancho | 90 mm | | Alto | 105 mm | | Tecnología | AGM | | EAN | 3661024056557 | | Terminal layout | Positive terminal on the left | | Cold cranking amps (EN) | 120 A | | Capacity (C20) | 9 Ah (c20) | ## Quick description **Tudor TK091 12V 9Ah 120A** is an auxiliary battery: it supports the Start-Stop system and on-board electronics during stops, without draining the main battery. ## Why this auxiliary battery? - **Designed for Start-Stop** built for the intensive cycling of modern cars - **2 to 3 times longer life** vs fitting a cheap conventional battery - **Fast recovery** recharges in minutes once the engine is running 🔌 Voltage 12 V ⚡ Capacity 9 Ah C20 🔋 Cold cranking 120 A EN-1 📏 Dimensions 150×90×105 mm ⚙️ Technology AGM 🧭 Polarity Positive on the left ⚖️ Weight 3,1 kg 🏷️ Model TUDOR Start-Stop Auxiliary ## Description ## Auxiliary battery Tudor TK091 Auxiliar 9Ah 120A 12V 12*V* Voltage 9*Ah* Capacity 120*A* Cold cranking 3.10*kg* Weight Designed for the auxiliary network of cars with advanced Start-Stop and heavy electronics, the **Tudor TK091** from the **Auxiliar** range stabilises the voltage with **9 Ah** with AGM technology. It measures 150 × 90 × 105 mm and the positive terminal on the left, the format sought by anyone replacing a 9 Ah battery in vehicles with an auxiliary battery. - Maintenance-free. - Sealed AGM: safe when installed in the cabin. - Stabilises the onboard network voltage. - AGM technology: absorbed electrolyte, no spills, can be mounted at an angle. ### What the Tudor TK091 is for The Tudor TK091 is designed for the auxiliary network of cars with advanced Start-Stop and heavy electronics: it stabilises the voltage and protects the main battery in cars with heavy electronics. Check that it matches your current battery in dimensions, terminals and hold-down: this reference has a weight of 3.10 kg. ### Will it fit your current battery tray? It has external dimensions of 150 × 90 × 105 mm and weighs 3.10 kg. The positive terminal on the left decides which side the cables end up on: it is the detail that causes most buying mistakes, so check it before ordering. Checking the three dimensions and the terminal position before buying avoids the most common mistake when replacing a battery. ### The Tudor TK091: Auxiliar range and AGM technology The TK091 is part of the Tudor **Auxiliar** range. Choosing the right reference within the series comes down to capacity, dimensions and terminals: technology and quality are common to the whole family. In an AGM battery the electrolyte is absorbed in glass-fibre separators: there is no free liquid, it cannot spill and it can be mounted at an angle. That construction lowers internal resistance, speeds up recharging and multiplies cycle life compared with a conventional battery. ### Why choose Tudor batteries Tudor is Spain's historic battery brand, today part of the Exide group. Its car, truck, motorcycle and leisure ranges are built with the same technology and controls as the group's original-equipment references. All the Tudor batteries in our catalogue are genuine product, recently manufactured and covered by the manufacturer's warranty. ### Manufacturer's warranty The Tudor TK091 comes with the **manufacturer's official warranty** against manufacturing defects. If it fails through a defect within the warranty period, we replace it at no cost to you. ### How to make it last longer Charge with a charger that has an AGM mode: it limits the voltage and protects the glass-fibre separators. Replace it with the same technology and capacity as the original. ### Delivery times and returns Same-day dispatch from our warehouse for in-stock orders placed **before 6:00 pm**: 24-48 working hours in mainland Spain and Portugal, 3 to 5 days in the islands and the rest of Europe. Returns are accepted for **14 days** if the battery has not been used (free collection on the Iberian mainland). You will receive tracking by email. ## Frequently asked questions ### Is the Tudor TK091 an AGM battery and what are the benefits of AGM? Yes. The TK091 from Tudor uses AGM (Absorbent Glass Mat) technology: a sealed lead-acid battery where the electrolyte is absorbed in a glass-fibre mat. It withstands more charge/discharge cycles than a conventional one, handles heat better and is the required technology for cars with advanced Start-Stop and regenerative braking. Expected lifespan: 5-8 years under normal conditions. ### Is the Tudor TK091 battery suitable for Start-Stop? Yes. As AGM technology it is designed for Start-Stop vehicles. AGM batteries support advanced Start-Stop and regenerative braking thanks to their higher cycle count. EFB is recommended for basic Start-Stop; AGM is recommended when regenerative braking is also present, thanks to its higher cycle capability. It works straight out of the box — on most modern vehicles registering the battery via OBD is recommended so the alternator automatically applies the optimal charging profile. ### How do I fit the TK091 model in my car? In most cars it fits in 15-30 minutes with a 10 mm wrench; if the battery is under the seat or in the boot the time can double. See the step-by-step guide on our blog. Quick summary: 1) switch off the engine and remove the key; 2) locate the original battery (engine bay, boot or under seat); 3) disconnect the negative (−) terminal first, then the positive (+); 4) loosen the hold-down clamp and remove the old battery; 5) fit the new one in the same orientation — with positive on the left match the polarity shown on the product sheet; 6) connect the positive (+) first, then the negative (−). On cars with Start-Stop or BMS, register the battery via OBD so the alternator applies the correct charging profile. ### How long does the Tudor TK091 battery last? Expected lifespan of the Tudor TK091 is 5 to 8 years in mild-climate car use with Start-Stop. In cold regions it drops slightly due to cold-start stress; in very hot regions it also drops because of electrolyte evaporation. To extend its life: avoid deep discharges (headlights on with engine off), have the alternator checked yearly, and keep the battery clean and properly secured. ### What size is this battery? Dimensions (length × width × height) are 150×90×105 mm — also written as 150x90x105 mm — following the European DIN standard. Always measure the space in your car before buying: even one extra millimetre can prevent the hold-down clamp from closing. The height shown includes the terminals. ### What polarity does the Tudor TK091 battery have? Polarity: positive on the left. To identify it, place the battery in front of you with the terminals facing you and check which side the positive (+, marked with a red ring) is on. Before buying, verify the polarity matches your current battery: switching polarity forces longer cables or system reconfiguration, with short-circuit risk. ### Is the TK091 valid for my vehicle? Three options to confirm: 1) enter your number plate in the finder (DGT/DVLA/KBA auto-detect your model and engine); 2) check the "Compatible vehicles" tab on this page, where we list every vehicle verified by our technical team; 3) if you cannot find your model, message us on WhatsApp with brand, model, engine and year — we reply during business hours (Mon–Fri 10:00–13:30 and 16:40–18:00 (Spanish time, CET)). The TK091 typically fits a wide range of European vehicles thanks to its standard DIN case format. ### What are the equivalents of the TK091 model? Directly interchangeable batteries (same dimensions, same polarity, same Ah and CCA) are the OEM equivalents from leading brands: Bosch, Tudor, Exide and, depending on the model, Banner or Yuasa. Exact equivalence depends on technology — an EFB cannot be replaced with a conventional battery in Start-Stop cars. See the "Equivalents" section to view recommended options at the same performance level. ### What advantages does the Tudor TK091 AGM battery offer over an EFB? AGM (Absorbent Glass Mat) technology uses absorbent fibreglass that retains the electrolyte, eliminating leaks and allowing up to 3× more charge/discharge cycles than a conventional battery. It is the recommended option when the car has advanced Start-Stop with regenerative braking (BMW EfficientDynamics, Mercedes Eco, Audi MHEV, Land Rover ECO, Volvo i-Stop). Withstands tilted positions, high vibration and extreme temperatures better than EFB. The Tudor TK091 is fully original and meets European EN 50342-6 standards for advanced Start-Stop. ### Do I need to register the Tudor TK091 on the car after installation? On most cars it is not strictly necessary — the alternator detects the new battery and adapts the charge automatically. It is recommended to register the battery via OBD so that the alternator applies the optimal charging profile from the first minute and extends the battery life as much as possible (especially on brands with sophisticated BMS: BMW, Mercedes, Audi, Volvo, Land Rover). Any workshop with an OBD scanner (~10-15 € labour) does it in 5 minutes. DIY apps: VCDS / Carista (VAG), Bimmercode (BMW), iCarsoft. If you do not register, the car will still start correctly — the alternator just takes a few days to adjust the profile. The Tudor TK091 ships factory-charged at 80-90% so you can use it straight after fitting. ## Equivalent batteries - [EXIDE EK091](https://baterias.com/gb/battery-exide-ek091-12v-9ah-120a) ## Technical team (editorial authorship) The FAQs, guides and comparisons on this site are reviewed by the baterias.com technical team — automotive battery specialists since 2012. → https://baterias.com/gb/technical-team --- *baterias.com — Automotive batteries · 2026-10-25*