# Optima BTDC-5.5 · Boat battery 12V 75Ah 975A

![Optima BTDC-5.5 · Boat battery 12V 75Ah 975A](https://bateriasonline.es/3845-home_default/optima-btdc-5-5.jpg)

> Optima BTDC-5.5 (ETN 852188000): 75 Ah boat battery, 975 A (EN), 325×165×238 mm, spiral AGM. Compare sizes and equivalents; 14-day returns.

**Category:** [Marine and boat batteries](https://bateriasonline.es/en/marine-boat-batteries) → [Optima](https://bateriasonline.es/en/optima-batteries)

- **Canonical URL**: https://bateriasonline.es/en/optima-btdc-5-5
- **Language**: en
- **Brand**: Optima
- **Reference**: BOL-OPTIMA-BTDC-5.5
- **EAN**: 4016987113592
- **MPN**: BTDC-5.5
- **Price**: 258,10 € (VAT incl., Spain)
- **Last updated**: 2026-11-06

## Technical specifications

| Feature | Value |
|---|---|
| Brand | Optima |
| Range | OPTIMA BLUE TOP |
| Application | Boats |
| Technology | Spiral AGM |
| Voltage | 12 V |
| Capacity | 75 Ah |
| Cold cranking amps (EN) | 975 A |
| Length | 325 mm |
| Width | 165 mm |
| Height | 238 mm |
| Weight | 27.9 kg |
| Terminal layout | 8 |
| Terminal type | 1 & 21 |
| ETN code | 852188000 |

## Quick description

Optima BTDC-5.5 (ETN 852 188 000, also written 852188000): boat battery with 12 V, 75 Ah and 975 A cold cranking current, measuring 325 × 165 × 238 mm.

## Description

## Who the Optima BTDC-5.5 is for

The Optima BTDC-5.5 is a battery for boats: engine starting or on-board service, depending on its design, with resistance to damp and hull vibration. With 75 Ah, the BTDC-5.5 suits boats that had a battery of that capacity.
The BTDC-5.5 belongs to the Optima OPTIMA BLUE TOP range. [See all Optima batteries](https://bateriasonline.es/en/optima-batteries)

## Equivalents and alternatives to the Optima BTDC-5.5

No other reference in the catalogue fully matches the dimensions and polarity of the BTDC-5.5; you will find the closest ones among our [marine and boat batteries](https://bateriasonline.es/en/marine-boat-batteries).

## Optima BTDC-5.5 vs BTDC-5.0 and BTDC-4.2

The real differences between the BTDC-5.5 and the closest Optima models:

| Model | Capacity | Cold cranking (EN) | Dimensions (mm) | Weight |
|---|---|---|---|---|
| Optima BTDC-5.5 (this one) | 75 Ah | 975 A | 325 × 165 × 238 | 27.9 kg |
| Optima BTDC-5.0 | 66 Ah | 765 A | 309 × 172 × 221 | 24.4 kg |
| Optima BTDC-4.2 | 55 Ah | 765 A | 254 × 175 × 200 | 20.6 kg |

- Optima BTDC-5.0: 9 Ah less, 210 A less cranking power, a different case (309 × 172 × 221 mm).
- Optima BTDC-4.2: 20 Ah less, 210 A less cranking power, a different case (254 × 175 × 200 mm).

## Spiral AGM technology in the BTDC-5.5

The BTDC-5.5 is a spiral-cell AGM battery. Perfect for 4x4s, marine use and vehicles with lots of electronics.

## Check this before ordering the Optima BTDC-5.5

- Length, width and height of the BTDC-5.5: 325 × 165 × 238 mm.
- With 75 Ah, the BTDC-5.5 replaces an original battery of that capacity or slightly less.
- Check the EN amps on your battery: if it says 975 A or less, the BTDC-5.5 covers your engine.

## Optima BTDC-5.5 codes and part numbers

Look for any of these BTDC-5.5 codes on your current battery or in the manufacturer's catalogue:

| Commercial reference | BTDC-5.5 |
|---|---|
| ETN code | 852188000 (also 852 188 000) |
| EAN | 4016987113592 |
| Case size according to Optima | 31 (BCI) |
| Base hold-down | B00 |
| Terminal type | 1 & 21 |
| Also known as | Optima 852188000 · Optima 852 188 000 |
| Not to be confused with | Optima BTDC-5.0 (66 Ah, 765 A, positive terminal on the left) |

## Frequently asked questions about the Optima BTDC-5.5

### Optima BTDC-5.5 or BTDC-5.0?

Compared with the BTDC-5.5, the Optima BTDC-5.0 has 9 Ah less and 210 A less cranking power. The BTDC-5.5 cranks harder; the BTDC-5.0 is only a good option if your original battery says 765 A or less. Mind the space: the BTDC-5.0 measures 309 × 172 × 221 mm.

### What is the ETN code of the Optima BTDC-5.5?

852188000, also written 852 188 000. The ETN (European Type Number) is printed on the label and used in parts catalogues.

### How much does the Optima BTDC-5.5 weigh?

The BTDC-5.5 weighs 27.9 kg. For reference, the Optima BTDC-5.0 (66 Ah) weighs 24.4 kg.

### Which charger does the Optima BTDC-5.5 need?

A charger with an AGM mode. If the battery has dropped below 10.5 V some chargers will not recognise it: use one with a recovery mode or one specific to spiral AGM.

## Other options if you are unsure about the BTDC-5.5

- [All marine and boat batteries](https://bateriasonline.es/en/marine-boat-batteries)
- [The whole Optima range](https://bateriasonline.es/en/optima-batteries)

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