Tudor TK800 AGM Microhybrid · Start-Stop battery 80Ah 800A

Yes, it is AGM. In an AGM battery such as the TK820, the electrolyte is not free but absorbed in a glass-fibre mat inside a sealed lead-acid battery. Compared with a conventional battery it withstands more charge/discharge cycles and handles heat better; it is the required technology for cars with advanced Start-Stop and regenerative braking.

AGM batteries support advanced Start-Stop and regenerative braking thanks to their higher cycle count. The Tudor TK820 is AGM, so yes, it is designed for Start-Stop cars. It needs nothing to work, though on most modern cars registering it via OBD is advisable so the alternator adjusts its charging profile. The general recommendation is EFB for basic Start-Stop and AGM where there is regenerative braking (it handles more cycles), unless the car manufacturer says otherwise.

If the car manufacturer lists any extra step in the handbook, follow it. More detail in how to replace the car battery. Tool: a 10 mm spanner. Time: 15-30 minutes on almost every car, and up to double if the battery is not under the bonnet but in the boot or under a seat. The right order: engine off and key out; disconnect the negative (−) first, then the positive (+); release the hold-down clamp, lift out the old battery and seat the new one in the same position (positive on the right), keeping the polarity; reconnect the positive (+) first and the negative (−) last. Start-Stop or BMS specifics: do not remove the IBS sensor on the negative terminal (just loosen the cable nut); after the swap, register the battery via OBD so the alternator charges with the right profile; and never step down in technology: if the car had AGM or EFB, the new one must be the same or better, as a conventional battery lasts only a few months.

As a rough estimate, the Tudor TK820 typically lasts 5 to 8 years in mild-climate car use with Start-Stop; it is a guide figure, not a guaranteed period. What weighs most: temperature (cold makes starts harder and intense heat evaporates the electrolyte), frequent short trips, the condition of the alternator and charging system, power draw while parked and maintenance, not forgetting the type of car and Start-Stop.

Before buying, measure the space in your car: one extra millimetre can stop the hold-down clamp from closing. The Tudor TK820 takes up 315×175×190 mm (length, width and height, terminals included), the European L4 case size.

Polarity of the Tudor TK820: positive on the right. It must match your current battery: reversed polarity means lengthening cables or reconfiguring the system, with a risk of short circuit. Seen from the front, terminals towards you, the positive (+) is the post with the red ring.

Three routes: the "Compatible vehicles" tab on this page, with the vehicles verified by our technical team; your number plate in the finder, from which DGT/DVLA/KBA detect model and engine; and WhatsApp, with make, model, engine and year, during business hours (Mon–Fri 10:00–13:30 and 16:30–18:00 (Spanish time, CET)). The car manufacturer's specifications always take priority over our tables.

The "Equivalents" section of this page gathers the recommended options with equivalent performance; remember that in Start-Stop cars an EFB should not be replaced with a conventional battery. A direct equivalent needs what this TK820 offers: 315×175×190 mm, positive on the right, the same Ah and CCA and AGM technology.

It has the same dimensions, voltage and technology as the TK800, although it is not a manufacturer-approved equivalent. Compared with the TK800 it has the same Ah and cranking power. It costs 28,65 € less. Check the positive terminal side and the original capacity before ordering; otherwise it is a straight swap.

It has the same dimensions, voltage and technology as the TK800, although it is not a manufacturer-approved equivalent. Compared with the TK800 it has 2 Ah less. It costs 10,50 € more. Check the positive terminal side and the original capacity before ordering; otherwise it is a straight swap.

The absorbent glass-fibre mat of an AGM retains the electrolyte, so it cannot leak and withstands considerably more cycles than a conventional battery. For regenerative braking systems such as BMW EfficientDynamics, Mercedes Eco, Audi MHEV, Land Rover ECO or Volvo i-Stop, AGM is the recommendation; it also copes better than an EFB with tilting, vibration and extreme temperatures. Cold cranking current (EN) of the Tudor TK820: 800 A.

The alternator detects the new battery and adapts the charge automatically, so on most cars it is not compulsory. Even so, it is advisable to register it via OBD so charging is optimum from the first minute and the battery lasts longer, particularly on BMW, Mercedes, Audi, Volvo or Land Rover, with more sophisticated BMS. Without registration there is no starting problem: the alternator adjusts the profile within a few days. Any workshop with an OBD scanner does it in a few minutes; DIY, with VCDS or Carista (VAG group), Bimmercode (BMW) or iCarsoft.