# Start-Stop battery Fulmen FK800 12V 80Ah 800A AGM

![Start-Stop battery Fulmen FK800 12V 80Ah 800A AGM](https://baterias.com/3756-home_default/battery-fulmen-fk800-12v-80ah-800a.jpg)

> Fulmen FK800 Start-Stop battery 12V 80Ah 800A AGM. Dimensions 315×175×190 mm, + terminal on the right. For Start-Stop vehicles.

**Category:** [Car batteries equipped with start stop system](https://baterias.com/gb/car-batteries-equipped-with-start-stop-system) → [Fulmen](https://baterias.com/gb/fulmen)

- **Canonical URL**: https://baterias.com/gb/battery-fulmen-fk800-12v-80ah-800a
- **Language**: en-GB
- **Brand**: Fulmen
- **Reference**: BCOM-FULMEN-FK800
- **EAN**: 3661024045728
- **MPN**: FK800
- **Last updated**: 2026-10-28
- **Stock**: Out of stock

## Technical specifications

| Feature | Value |
|---|---|
| Brand | FULMEN |
| Reference | FK800 |
| Model | FULMEN AGM |
| Voltage (V) | 12 V |
| Largo | 315 mm |
| Ancho | 175 mm |
| Alto | 190 mm |
| Peso | 23.1 kg |
| Tecnología | AGM |
| EAN | 3661024045728 |
| Terminal layout | Positive terminal on the right |
| Hold down | B13 |
| Cold cranking amps (EN) | 800 A |
| Capacity (C20) | 80 Ah (c20) |
| Case type | L04 |

## Quick description

**Fulmen FK800 12V 80Ah 800A** is a dedicated Start-Stop battery with AGM/EFB technology. Withstands intensive cycling at traffic-light stops (hundreds of cranks per day), recharges quickly while driving and keeps comfort loads alive during long idle periods.

## Why this Start-Stop 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
80 Ah C20

🔋 Cold cranking
800 A EN-1

📏 Dimensions
315×175×190 mm

⚙️ Technology
AGM

🧭 Polarity
Positive on the right

⚖️ Weight
23,1 kg

🏷️ Model
FULMEN AGM

## Description

## Start-Stop battery Fulmen FK800 80Ah 800A 12V

12*V* Voltage
80*Ah* Capacity
800*A* Cold cranking
23.10*kg* Weight

The **Fulmen FK800 Start-Stop battery** offers **12 V**, **80 Ah** and **800 A** of cold cranking current (EN) with AGM technology, and is built for cars with Start-Stop, regenerative braking and heavy electrical loads. Measuring 315 × 175 × 190 mm and the positive terminal on the right, it is the direct replacement for Start-Stop cars fitted from the factory with a 80 Ah battery of this format.
- Keeps comfort loads running with the engine off at the lights.
- Direct replacement for the original Start-Stop battery.
- AGM: faster recharging and better cycle resistance than a conventional battery.
- Fast recharge on the move thanks to low internal resistance.

### What the Fulmen FK800 is for

The Fulmen FK800 is designed for cars with Start-Stop, regenerative braking and heavy electrical loads. If your car was fitted with an AGM or EFB battery, always replace it with the same technology: a conventional model would degrade within months. Check that it matches your current battery in dimensions, terminals and hold-down: this reference has a weight of 23.10 kg and B13 hold-down.

### Will it fit your current battery tray?

The Fulmen FK800 is made in the 315 × 175 × 190 mm format and weighs 23.10 kg. The positive terminal on the right decides which side the cables end up on: it is the detail that causes most buying mistakes, so check it before ordering. It uses a B13 hold-down, the system that anchors and connects it in the vehicle. Before replacing it, measure your current battery tray: if all three dimensions and the terminal positions match, the swap is direct and needs no adapters.

### Technology inside the Fulmen FK800

The FK800 is one of the Fulmen references for this type of use; it shares the same manufacturing and quality-control criteria as the rest of the brand's catalogue.
AGM (Absorbent Glass Mat) technology seals the electrolyte in glass microfibre. The result is a maintenance-free battery that is highly vibration-resistant and able to withstand deep discharges that would ruin a classic lead-acid battery.

### Why choose Fulmen batteries

Fulmen is the historic French brand of the Exide group: batteries made on the same lines and with the same technology as original equipment, widely used by workshops across Europe. We guarantee that every Fulmen arrives new, charged and with the manufacturer's full warranty.

### Warranty and coverage

The Fulmen FK800 comes with the **manufacturer's official warranty**. To keep it valid, always fit the same technology as the original battery (AGM or EFB) and register the replacement if your vehicle requires it.

### Usage and maintenance tips

If the vehicle only does very short trips, a periodic maintenance charge with an AGM/EFB-compatible charger greatly extends its life. Do not mix technologies: a conventional battery in a Start-Stop car degrades within months.

### Delivery times and returns

Orders placed **before 6:00 pm** with the battery in stock ship the same day. Delivery in mainland Spain and Portugal takes 24-48 working hours; for the Balearic Islands and the rest of the European Union allow 3 to 5 working days. You have **14 days** to return an unused battery; in mainland Spain and Portugal collection is free. We email you the tracking number as soon as the parcel ships.

## Frequently asked questions

### Is the FK800 model AGM? What does this technology offer?

Yes: the FK800 from Fulmen uses AGM (Absorbent Glass Mat) technology, a sealed lead-acid battery whose electrolyte soaks a glass-fibre mat. 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.

### Is the FK800 model suitable for Start-Stop cars?

Yes: being AGM, the Fulmen FK800 is designed for Start-Stop cars. AGM batteries support advanced Start-Stop and regenerative braking thanks to their higher cycle count. If the car recovers energy when braking, AGM is recommended for its higher cycle count; for basic Start-Stop, EFB. The manufacturer's specification comes first. Once fitted it is ready to go; registering it via OBD, advisable on most modern models, lets the alternator charge with the optimum profile.

### What should I bear in mind when fitting this Start-Stop battery?

Our blog guide covers it in detail; if the owner's handbook describes a different procedure, follow the manufacturer. Allow 15-30 minutes and a 10 mm spanner for a L4 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. 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. On cars with Start-Stop or BMS, registering the battery via OBD makes the alternator charge with the correct profile. Mind the IBS sensor on the negative terminal too: loosen the cable nut, not the sensor. And the replacement must be the same technology (AGM or EFB) or higher: a conventional battery fails within months.

### How long does the Fulmen FK800 battery last?

As a guide, you can expect the Fulmen FK800 to last 5 to 8 years in mild-climate car use with Start-Stop, although the real figure may be higher or lower. 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.

### What are the measurements of the FK800 model?

It measures 315×175×190 mm in length × width × height, with the terminals included in the height; that is the European L4 case size. Measure the battery tray before ordering: a one-millimetre difference is enough for the hold-down clamp not to close.

### What polarity does the Fulmen FK800 battery have?

On the Fulmen FK800, the polarity is positive on the right. To check, stand the battery in front of you with the terminals nearest you: the positive (+) is the one with the red ring. A change of polarity from the original means longer cables or a reconfigured system and can cause a short circuit: check it before ordering.

### Will the Fulmen FK800 battery fit my car?

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)). In every case, the car manufacturer's specifications (owner's handbook) take precedence.

### Which batteries are equivalent to the Fulmen FK800?

Interchangeable means the same dimensions, same polarity, same Ah and same CCA; for the FK800, 80 Ah (800 A cranking). Technology matters too: in Start-Stop cars, an EFB cannot be replaced with a conventional battery. The options at the same level are in the "Equivalents" section of this page.

### Fulmen FK800 or Varta A6: which one to choose?

The Varta alternative that fits where the FK800 goes, with the same polarity. Compared with the FK800 it has the same Ah and cranking power. It costs €149.95 more. A straight swap with nothing to adapt; the difference is the price and the brand you prefer.

### Fulmen FK800 or Exide EK800: which one to choose?

It is the verified Exide equivalent for the FK800 tray. Compared with the FK800 it has 2 Ah more. It costs €119.20 more. Decide by price, brand preference and availability: both fit and crank the same.

### What advantages does the Fulmen FK800 AGM battery offer over an EFB?

The Fulmen FK800 has a capacity of 80 Ah. AGM means Absorbent Glass Mat: the electrolyte soaks a glass-fibre mat (no spills), and an AGM battery lasts many more cycles than a conventional one. 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.

### Do I need to register the Fulmen FK800 on the car after installation?

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.


## Equivalent batteries

- [VARTA F21](https://baterias.com/gb/battery-varta-f21-agm-12v-80ah-800a)
- [TUDOR TK800](https://baterias.com/gb/battery-tudor-tk800-80ah-800a)
- [VARTA LA80](https://baterias.com/gb/battery-varta-la80agm-12v-80ah-800a)
- [EXIDE EK800](https://baterias.com/gb/battery-exide-ek800-12v-80ah-800a)
- [VARTA A6](https://baterias.com/gb/battery-varta-a6-agm-12v-80ah-800a)
- [KRONOBAT EV-80-AGM](https://baterias.com/gb/best-price-battery-12v-80ah-agm-ev-80-agm)

## 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

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*baterias.com — Automotive batteries · 2026-11-08*