# Fulbat AUX12 · Auxiliary battery 12V 10.5Ah

![Fulbat AUX12 · Auxiliary battery 12V 10.5Ah](https://bateriasonline.es/586-home_default/fulbat-aux12.jpg)

> Fulbat AUX12: 10.5 Ah auxiliary battery, 150×87×130 mm, positive terminal on the left, AGM. Equivalent to Exide EK111 and Tudor TK111.

**Category:** [Auxiliary batteries (back-up and in-vehicle service)](https://bateriasonline.es/en/auxiliary-backup-batteries) → [Fulbat](https://bateriasonline.es/en/fulbat-batteries)

- **Canonical URL**: https://bateriasonline.es/en/fulbat-aux12
- **Language**: en
- **Brand**: Fulbat
- **Reference**: BOL-FULBAT-AUX12
- **MPN**: AUX12
- **Last updated**: 2026-11-06

## Technical specifications

| Feature | Value |
|---|---|
| Brand | Fulbat |
| Range | FULBAT Auxiliary AGM |
| Application | Auxiliary and back-up use |
| Technology | AGM |
| Voltage | 12 V |
| Capacity | 10.5 Ah |
| Length | 150 mm |
| Width | 87 mm |
| Height | 130 mm |
| Weight | 4.1 kg |
| Polarity | Positive terminal on the left |

## Quick description

The Fulbat AUX12 is an auxiliary battery (AGM) with 12 V and 10.5 Ah, measuring 150 × 87 × 130 mm, with the positive terminal on the left.

## Description

## Who the Fulbat AUX12 is for

The Fulbat AUX12 is the second battery fitted in many modern cars. Without it, Start-Stop or back-up warnings appear on the dashboard.
The AUX12 belongs to the Fulbat FULBAT Auxiliary AGM range. [See all Fulbat batteries](https://bateriasonline.es/en/fulbat-batteries)

## What it means that the AUX12 is AGM

Inside, the AUX12 has glass fibre separators (AGM) that hold the electrolyte. The AUX12 needs a charger with an AGM mode that does not exceed 14.7 V.

## Fulbat AUX12 vs AUX14-J, AUX9 and AUX14: differences

How the AUX12 compares with Fulbat batteries of similar size and capacity:

| Model | Capacity | Dimensions (mm) | Positive | Weight |
|---|---|---|---|---|
| Fulbat AUX12 (this one) | 10.5 Ah | 150 × 87 × 130 | left | 4.1 kg |
| Fulbat AUX14-J | 14 Ah | 150 × 87 × 145 | left | 4.62 kg |
| Fulbat AUX9 | 8.4 Ah | 150 × 87 × 105 | left | – |
| Fulbat AUX14 | 12.6 Ah | 150 × 87 × 145 | left | 4.53 kg |

- Fulbat AUX14-J: 3.5 Ah more, a different case (150 × 87 × 145 mm).
- Fulbat AUX9: 2.10 Ah less, a different height (105 mm instead of 130 mm). It is the option if your battery tray cannot take the 130 mm height of the AUX12.
- Fulbat AUX14: 2.10 Ah more, a different height (145 mm instead of 130 mm). It only fits if there is room for 145 mm of height.

## Equivalents and alternatives to the Fulbat AUX12

Other AGM batteries that fit the AUX12's tray with the same polarity: an AGM can only be replaced by another AGM.

| Model | Technology | Capacity | Dimensions (mm) |
|---|---|---|---|
| Exide EK111 | AGM | 11 Ah | 150 × 90 × 130 |
| Tudor TK111 | AGM | 11 Ah | 150 × 90 × 130 |
| Fulmen FK111 | AGM | 11 Ah | 150 × 90 × 130 |
| Deta DK111 | AGM | 11 Ah | 150 × 90 × 130 |

## Part numbers and codes for the Fulbat AUX12

This is how the Fulbat AUX12 appears on the label and in parts catalogues:

| Commercial reference | AUX12 |
|---|---|
| Not to be confused with | Fulbat AUX14 (12.6 Ah) |

## Before ordering the AUX12, check this

- Your current battery should say about 10.5 Ah; a little more is also fine.
- The AUX12 has the positive terminal on the left: compare it with your current battery.
- Measure the space: the AUX12 takes up 150 × 87 × 130 mm.

## Frequently asked questions about the Fulbat AUX12

### AUX12 or AUX14-J: which one suits me?

Compared with the AUX12, the Fulbat AUX14-J has 3.5 Ah more. With 14 Ah, the AUX14-J runs longer between charges than the AUX12 (10.5 Ah). Mind the space: the AUX14-J measures 150 × 87 × 145 mm.

### Fulbat AUX12 or AUX9/AUX14: what changes?

Mainly the height: the AUX12 is 130 mm tall and the Fulbat AUX9 105 mm, with the same length and width and 8.4 Ah against 10.5 Ah. The Fulbat AUX14 is 145 mm tall, with 12.6 Ah and A. Before choosing between the AUX12 and the AUX9, measure the free height of the battery compartment with the cover or bonnet closed.

### How much does the Fulbat AUX12 weigh?

4.1 kg, with 10.5 Ah of capacity. For reference, the Fulbat AUX14-J (14 Ah) weighs 4.62 kg.

### Which battery is equivalent to the Fulbat AUX12?

Only other AGM batteries with its dimensions and polarity: Exide EK111, Tudor TK111 and Fulmen FK111. Neither an EFB nor a conventional battery replaces the AUX12.

### Which side is the positive terminal on the Fulbat AUX12?

On the AUX12, the positive terminal is on the left with the terminals facing you: compare it with your current battery, because with reversed polarity the cables will not reach.

### Is the auxiliary battery replaced together with the main one?

Not necessarily, but they usually age together. If the main battery is over five years old, check the auxiliary one too.

## More batteries to compare with the AUX12

- [All auxiliary batteries (back-up and in-vehicle service)](https://bateriasonline.es/en/auxiliary-backup-batteries)
- [More Fulbat models](https://bateriasonline.es/en/fulbat-batteries)
- [Exide EK111](https://bateriasonline.es/en/exide-ek111) · 11 Ah, 150 A, 150×90×130 mm
- [Tudor TK111](https://bateriasonline.es/en/tudor-tk111) · 11 Ah, 150 A, 150×90×130 mm

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*bateriasonline.es — Batteries and accessories · 2026-11-10*