Fulmen FK720 · Start-Stop battery 72Ah 760A AGM

Yes. The Fulmen FK720 is AGM (Absorbent Glass Mat): sealed lead-acid, with the electrolyte absorbed in glass fibre. Its advantages: more charge/discharge cycles than a conventional battery and better heat tolerance. It is also required in cars with advanced Start-Stop and regenerative braking.

Yes. It is a AGM battery of 72 Ah, designed for vehicles with 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.

Allow 15-30 minutes and a 10 mm spanner for a L3 case like this one. If the car keeps its battery in the boot or under a seat, it can take up to twice as long. 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. What matters most is the terminal order: removing, negative (−) before positive (+); refitting, positive (+) before negative (−). In between, with the engine off and the key out, release the clamp and fit the new battery the same way round as the original, positive on the right (polarity). Our blog guide covers it in detail; if the owner's handbook describes a different procedure, follow the manufacturer.

Estimated lifespan of the Fulmen FK720: 5 to 8 years in mild-climate car use with Start-Stop. Treat it as an approximate guide, as every case is different. Actual lifespan varies with climate (cold starts, heat evaporating the electrolyte), with usage and short journeys, with the condition of the alternator and charging system, with power draw while parked and with maintenance; the type of car and Start-Stop also count.

The Fulmen FK720 takes up 278×175×190 mm (length, width and height, terminals included), the European L3 case size, with a B13 hold-down. Before buying, measure the space in your car: one extra millimetre can stop the hold-down clamp from closing.

The FK720 has the positive on the right in a L3 case: that is its polarity. Face the battery with its terminals nearest you and see which side the positive post (+, red ring) is on. 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.

According to our data, 1,221 verified vehicle versions are compatible with the FK720. The quickest way is to enter your number plate in the finder: DGT/DVLA/KBA detect model and engine. You can also look at the "Compatible vehicles" tab, verified by our technical team, or send us make, model, engine and year on WhatsApp; we answer 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. Interchangeable means the same dimensions, same polarity, same Ah and same CCA; for the FK720, 72 Ah (760 A cranking).

The absorbent glass-fibre mat of an AGM retains the electrolyte, so it cannot leak and withstands considerably more cycles than a conventional battery. Compared with an EFB it resists tilted positions, heavy vibration and extreme temperatures better, and it is the recommended option where there is regenerative braking (BMW EfficientDynamics, Mercedes Eco, Audi MHEV, Land Rover ECO, Volvo i-Stop). The Fulmen FK720 has a capacity of 72 Ah.

It is not strictly necessary on most cars, because the alternator detects the change and adapts the charge. The advisable step is to register it via OBD: the charging profile is optimum from the first minute and the battery lasts longer, especially on brands with sophisticated BMS (BMW, Mercedes, Audi, Volvo, Land Rover). Without registration there is no starting problem: the alternator adjusts the profile within a few days. Any garage with an OBD scanner can do it in a few minutes. If you prefer to do it yourself: VCDS / Carista (VAG), Bimmercode (BMW) or iCarsoft.