Fulbat AUX9 · Auxiliary battery 12V 8.4Ah AGM
Specifications
| Brand | FULBAT |
|---|---|
| Part number | AUX9 |
| Voltage (V) | 12V |
| Capacity (C20) | 8.40Ah |
| Capacity (C10) | 8Ah (c10) |
| Technology | AGM |
| Length | 150mm |
| Width | 87mm |
| Height | 105mm |
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Polarity: positive on the left. Check it matches your current battery before buying.
Fulbat AUX9 12V 8Ah 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-Stopbuilt for the intensive cycling of modern cars
- 2 to 3 times longer lifevs fitting a cheap conventional battery
- Fast recoveryrecharges in minutes once the engine is running
Voltage
12 V
Capacity
8 Ah
Dimensions
150×87×105 mm
Technology
AGM
Polarity
Positive on the left
Model
FULBAT Auxiliary AGM
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Auxiliary battery Fulbat AUX9 8.4Ah 12V
12VVoltage
8.4AhCapacity
The 12 V, 8.4 Ah Fulbat AUX9 auxiliary battery with AGM technology powers the auxiliary network of cars with advanced Start-Stop and heavy electronics. It measures 150 × 87 × 105 mm and the positive terminal on the left, the format sought by anyone replacing a 8.4 Ah battery in vehicles with an auxiliary battery.
- Stabilises the onboard network voltage.
- AGM technology: absorbed electrolyte, no spills, can be mounted at an angle.
- Maintenance-free.
- Sealed AGM: safe when installed in the cabin.
What the Fulbat AUX9 is for
As an auxiliary battery, the Fulbat AUX9 works alongside the main one; replace it when the vehicle reports a fault in the support network.
Size, terminals and hold-down of the Fulbat AUX9
It has external dimensions of 150 × 87 × 105 mm. 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.
Why choose Fulbat batteries
Fulbat has manufactured in France since 1978 and specialises in motorcycles and light vehicles. Its catalogue is short and clear, covers almost the whole fleet and works only with sealed, leak-free batteries. All the Fulbat batteries in our catalogue are genuine product, recently manufactured and covered by the manufacturer's warranty.
Technology inside the Fulbat AUX9
The AUX9 is one of the Fulbat references for this type of use; it shares the same manufacturing and quality-control criteria as the rest of the brand's catalogue.
AGM means the acid is held in a glass mat instead of floating free. That is why the battery can be installed in the cabin without gases, survives more cycles and recovers its charge quickly.
Usage and maintenance tips
Replace it with the same technology and capacity as the original. The auxiliary battery works alongside the main one: if a support-network fault warning appears, check both.
Manufacturer's warranty
The Fulbat AUX9 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.
Shipping, delivery 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 and Canary 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.
BCOM-FULBAT-AUX9
Data sheet
- Brand
- FULBAT
- Model
- FULBAT Auxiliary AGM
- Voltage (V)
- 12V
- Length
- 150mm
- Width
- 87mm
- Height
- 105mm
- Technology
- AGM
- Terminal layout
- Positive left
- Capacity (C20)
- 8.40Ah
- Capacity (C10)
- 8Ah (c10)
Specific References
- MPN
- AUX9
Comparison: Fulbat AUX9 vs equivalents
The Fulbat AUX9 is interchangeable with these equivalent references: AUX9 (Varta), 511902023 (Varta), 511901014 (Varta), 509901020 (Varta), TK091 (Tudor).
| Product | Specifications | Technology | Price |
|---|---|---|---|
Fulbat
AUX9
This battery
|
|||
Varta
AUX9
|
12V 9Ah 130A | Lead-acid | €59.10 |
Varta
511902023
|
12V 11Ah 230A | AGM | €47.30 |
Varta
511901014
|
12V 11Ah 160A | AGM | €43.20 |
Varta
509901020
|
12V 9Ah 200A | AGM | €88.70 |
Tudor
TK091
|
12V 9Ah 120A | AGM | €61.70 |
Equivalences verified by our technical team: same dimensions, polarity, capacity and CCA. Official manufacturer warranty on every option.
Recommended accessories
How to change the battery
Step-by-step guide to replace your car battery in 15-30 minutes (longer if the battery is under the seat or in the boot) without losing vehicle settings.
Step 1. Prepare the vehicle
Park on a flat surface, switch off the engine and remove the key. Make sure all lights and electrical accessories are off. Wait 1-2 minutes before starting.
Step 2. Locate the battery
Open the bonnet. The battery is usually in the engine bay, but in many modern cars it may be in the boot or under the passenger seat. Check the manual if you cannot find it.
Step 3. Disconnect the negative (−) terminal
Use the 10 mm wrench to loosen the negative cable nut (black, marked −) and remove the cable from the post. Move it aside so it cannot touch any bodywork.
Step 4. Disconnect the positive (+) terminal
Repeat with the positive cable (red, marked +). Important: never let a terminal touch metal of the car while the other is still connected.
Step 5. Remove the old battery
Loosen the bottom hold-down clamp with the same wrench. Lift the battery carefully (it can weigh 15-25 kg). Clean the tray with a brush and baking soda if there is corrosion.
Step 6. Install the new battery
Place the battery in the same orientation as the old one (positive terminal on the same side). Tighten the hold-down clamp firmly.
Step 7. Connect the cables
Connect the positive (+) terminal first, then the negative (−). Tighten the nuts with the wrench until each terminal does not move. Apply anti-spark grease if you have any.
Step 8. Verify the engine starts
Close the bonnet. Start the engine to confirm everything works. On cars with Start-Stop or a BMS, you may need to register the battery via OBD so the alternator applies the correct charging profile.
Frequently asked questions
How do I fit the AUX9 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 this page. 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 — 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 Fulbat AUX9 battery last?
Expected lifespan of the Fulbat AUX9 is 4 to 7 years in regular use (depends on technology and climate). 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 are the dimensions of the Fulbat AUX9 battery?
Dimensions (length × width × height) are 150×87×105 mm — also written as 150x87x105 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.
Will the Fulbat AUX9 battery fit my car?
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 AUX9 typically fits a wide range of European vehicles thanks to its standard DIN case format.
Which interchangeable batteries are there for this one?
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.
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