# Optima BTDC-5.0 · Boat battery 12V 66Ah 765A

![Optima BTDC-5.0 · Boat battery 12V 66Ah 765A](https://bateriasonline.es/3842-home_default/optima-btdc-5-0.jpg)

> Optima BTDC-5.0 (ETN 827227000): 66 Ah boat battery, 765 A (EN), 309×172×221 mm, positive terminal on the left, D31 case, spiral AGM.

**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-5-0
- **Language**: en
- **Brand**: Optima
- **Reference**: BOL-OPTIMA-BTDC-5.0
- **EAN**: 4016987130346
- **MPN**: BTDC-5.0
- **Price**: 220,86 € (VAT incl., Spain)
- **Last updated**: 2026-10-27

## Technical specifications

| Feature | Value |
|---|---|
| Brand | Optima |
| Range | OPTIMA BLUE TOP |
| Application | Boats |
| Technology | Spiral AGM |
| Voltage | 12 V |
| Capacity | 66 Ah |
| Cold cranking amps (EN) | 765 A |
| Length | 309 mm |
| Width | 172 mm |
| Height | 221 mm |
| Weight | 24.4 kg |
| Polarity | Positive terminal on the left |
| Terminal type | 1 & 21 |
| Case size | D31 (306 × 173 × 225 mm) |
| ETN code | 827227000 |

## Quick description

Optima BTDC-5.0 (ETN 827 227 000, also written 827227000): boat battery with 12 V, 66 Ah and 765 A cold cranking current, case size D31 (309 × 172 × 221 mm), with the positive terminal on the left.

## Description

## Who the Optima BTDC-5.0 is for

The Optima BTDC-5.0 is a battery for boats: engine starting or on-board service, depending on its design, with resistance to damp and hull vibration. Check whether your boat needs starting, service or a dual-purpose battery before choosing.
The BTDC-5.0 belongs to the Optima OPTIMA BLUE TOP range. [See all Optima batteries](https://bateriasonline.es/en/optima-batteries)

## What it means that the BTDC-5.0 is spiral AGM

The BTDC-5.0 is a spiral-cell AGM battery. Perfect for 4x4s, marine use and vehicles with lots of electronics.

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

What sets the BTDC-5.0 apart from its neighbours in the Optima range:

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

- Optima BTDC-5.5: 9 Ah more, 210 A more cranking power, a different case (325 × 165 × 238 mm).
- Optima BTDC-4.2: 11 Ah less, the same cranking power, a different case (254 × 175 × 200 mm).

## Equivalents and alternatives to the Optima BTDC-5.0

No other reference in the catalogue fully matches the dimensions and polarity of the BTDC-5.0; you will find the closest ones among our [marine and boat batteries](https://bateriasonline.es/en/marine-boat-batteries).

## Optima BTDC-5.0 codes and part numbers

The BTDC-5.0 is listed under these codes on labels, in garages and in catalogues:

| Commercial reference | BTDC-5.0 |
|---|---|
| ETN code | 827227000 (also 827 227 000) |
| EAN | 4016987130346 |
| Case size (EN) | D31 |
| Case size according to Optima | 27 (BCI) |
| Base hold-down | B00 |
| Terminal type | 1 & 21 |
| Also known as | Optima 827227000 · Optima 827 227 000 |
| Not to be confused with | Optima BTDC-5.5 (75 Ah, 975 A) |

## Check this before ordering the Optima BTDC-5.0

- Check the EN amps on your battery: if it says 765 A or less, the BTDC-5.0 covers your engine.
- Your current battery should say about 66 Ah; a little more is also fine.
- Polarity of the BTDC-5.0: positive terminal on the left (if yours has it on the other side, the cables will not reach).
- Measure the space: the BTDC-5.0 takes up 309 × 172 × 221 mm (European case size D31).

## Frequently asked questions about the Optima BTDC-5.0

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

Compared with the BTDC-5.0, the Optima BTDC-5.5 has 9 Ah more and 210 A more cranking power. If your current battery says 975 A or more, choose the BTDC-5.5; if it says 765 A or less, the BTDC-5.0 is enough. Mind the space: the BTDC-5.5 measures 325 × 165 × 238 mm.

### What is the ETN code of the Optima BTDC-5.0?

827227000, also written 827 227 000. The ETN (European Type Number) is printed on the label and used in parts catalogues.

### How much does the Optima BTDC-5.0 weigh?

The BTDC-5.0 weighs 24.4 kg. For reference, the Optima BTDC-5.5 (75 Ah) weighs 27.9 kg.

### What case size is the Optima BTDC-5.0?

Case size D31: 309 × 172 × 221 mm (Optima lists it as 27 (BCI)). The BTDC-5.0 fits any standard D31 battery tray.

### Which side is the positive terminal on the Optima BTDC-5.0?

The BTDC-5.0 has the positive terminal on the left, looking at the battery from its long side with the terminals closest to you.

### How do I look after the boat battery in winter?

Leave it 100% charged, disconnected or on a marine maintenance charger. A battery that spends the winter half-discharged loses capacity permanently.

## Keep comparing: alternatives to the BTDC-5.0

- [More 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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