# Optima RTS-2.1 · Classic car battery 6V 50Ah 815A

![Optima RTS-2.1 · Classic car battery 6V 50Ah 815A](https://bateriasonline.es/3861-home_default/optima-rts-2-1.jpg)

> Optima RTS-2.1 (ETN 810355000): 50 Ah classic car battery, 815 A (EN), 254×90×203 mm, spiral AGM.

**Category:** [6V batteries for classic cars](https://bateriasonline.es/en/classic-car-batteries) → [Optima](https://bateriasonline.es/en/optima-batteries)

- **Canonical URL**: https://bateriasonline.es/en/optima-rts-2-1
- **Language**: en
- **Brand**: Optima
- **Reference**: BOL-OPTIMA-RTS-2.1
- **EAN**: 4016987113516
- **MPN**: RTS-2.1
- **Price**: 160,14 € (VAT incl., Spain)
- **Last updated**: 2026-11-06

## Technical specifications

| Feature | Value |
|---|---|
| Brand | Optima |
| Range | OPTIMA RED TOP |
| Application | Classic cars |
| Technology | Spiral AGM |
| Voltage | 6 V |
| Capacity | 50 Ah |
| Cold cranking amps (EN) | 815 A |
| Length | 254 mm |
| Width | 90 mm |
| Height | 203 mm |
| Weight | 8.9 kg |
| Terminal layout | 8 |
| ETN code | 810355000 |

## Quick description

Optima RTS-2.1 (ETN 810 355 000, also written 810355000): classic car battery (spiral AGM) with 6 V, 50 Ah and 815 A cold cranking current, measuring 254 × 90 × 203 mm.

## Description

## The Optima RTS-2.1 at a glance

The Optima RTS-2.1 is a starter battery for classic and collector cars, with the format and terminals used by vehicles of its era.
At 50 Ah it covers petrol compacts and small diesels, the best-selling format in Europe. The RTS-2.1 belongs to the Optima OPTIMA RED TOP range. [See all Optima batteries](https://bateriasonline.es/en/optima-batteries)

## Optima RTS-2.1 vs YTS-2.1: which one to choose?

What sets the RTS-2.1 apart from its neighbours in the Optima range:

| Model | Capacity | Cold cranking (EN) | Dimensions (mm) | Weight |
|---|---|---|---|---|
| Optima RTS-2.1 (this one) | 50 Ah | 815 A | 254 × 90 × 203 | 8.9 kg |
| Optima YTS-2.1 | 55 Ah | 765 A | 255 × 90 × 206 | 10.6 kg |

- Optima YTS-2.1: 5 Ah more, 50 A less cranking power, a different case (255 × 90 × 206 mm).

## Part numbers and codes for the Optima RTS-2.1

Look for any of these RTS-2.1 codes on your current battery or in the manufacturer's catalogue:

| Commercial reference | RTS-2.1 |
|---|---|
| ETN code | 810355000 (also 810 355 000) |
| EAN | 4016987113516 |
| Base hold-down | B11 |
| Also known as | Optima 810355000 · Optima 810 355 000 |
| Not to be confused with | Optima YTS-2.1 (55 Ah, 765 A, positive terminal on the left) |

## Equivalents and alternatives to the Optima RTS-2.1

We have no other battery with exactly the dimensions and polarity of the RTS-2.1. Browse the rest of our [6V batteries for classic cars](https://bateriasonline.es/en/classic-car-batteries) to compare close options.

## Check this before ordering the Optima RTS-2.1

- The RTS-2.1 needs 254 × 90 × 203 mm of space: measure it with the hold-down clamp in place.
- With 50 Ah, the RTS-2.1 replaces an original battery of that capacity or slightly less.
- Check the EN amps on your battery: if it says 815 A or less, the RTS-2.1 covers your engine.

## Inside the RTS-2.1: spiral AGM technology

The RTS-2.1 is a spiral-cell AGM battery. Perfect for 4x4s, marine use and vehicles with lots of electronics.

## Frequently asked questions about the Optima RTS-2.1

### RTS-2.1 or YTS-2.1: which one suits me?

Compared with the RTS-2.1, the Optima YTS-2.1 has 5 Ah more and 50 A less cranking power. The RTS-2.1 cranks harder; the YTS-2.1 is only a good option if your original battery says 765 A or less. Mind the space: the YTS-2.1 measures 255 × 90 × 206 mm.

### What is the ETN code of the Optima RTS-2.1?

810355000, also written 810 355 000. The ETN (European Type Number) is printed on the label and used in parts catalogues.

### How much does the Optima RTS-2.1 weigh?

8.9 kg, with 50 Ah of capacity. For reference, the Optima YTS-2.1 (55 Ah) weighs 10.6 kg.

### Which charger does the Optima RTS-2.1 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 RTS-2.1

- [All 6V batteries for classic cars](https://bateriasonline.es/en/classic-car-batteries)
- [Full Optima catalogue](https://bateriasonline.es/en/optima-batteries)

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