Fulmen FL550 · Start-Stop battery 12V 55Ah 540A EFB

Yes. The FL550 is an EFB (Enhanced Flooded Battery): flooded lead-acid reinforced with plate additives. Withstands more cycles than a conventional but fewer than an AGM. Fitted to cars with basic Start-Stop (no regenerative braking). More affordable than an equivalent AGM, lifespan 4-6 years.

Yes. As EFB technology it is designed for Start-Stop vehicles. EFB batteries cover basic Start-Stop (no regenerative braking). 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.

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 right 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.

Expected lifespan of the Fulmen FL550 is 4 to 6 years in basic Start-Stop car use. 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.

Dimensions (length × width × height) are 207×175×190 mm — also written as 207x175x190 mm and correspond to the European L1 case size — 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.

Polarity: positive on the right. 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.

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 FL550 typically fits a wide range of European vehicles thanks to its standard DIN case format.

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.

An EFB (Enhanced Flooded Battery) is a flooded lead-acid battery reinforced with plate additives (carbon and polyethylene) and thicker grids. It withstands twice the cycles of a conventional battery and handles deep discharges better, but less than an AGM. It is the original fitment on cars with basic Start-Stop (no regenerative braking): Renault Energy TCe, Peugeot/Citroën PureTech, Fiat MultiAir, Hyundai/Kia ISG, Ford EcoBoost. If your car came with EFB from the factory, this is the correct battery — upgrading to AGM is optional (marginal improvement). If it came with AGM, EFB may fall short: better fit AGM. The Fulmen FL550 is original and meets EN 50342-6.

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 Fulmen FL550 ships factory-charged at 80-90% so you can use it straight after fitting.