# Optima RTF-4.2 · Car battery 12V 50Ah 815A

![Optima RTF-4.2 · Car battery 12V 50Ah 815A](https://bateriasonline.es/3852-home_default/optima-rtf-4-2.jpg)

> Optima RTF-4.2 (ETN 804250000): 50 Ah car battery, 815 A (EN), 254×185×184 mm, positive terminal on the left, spiral AGM.

**Category:** [Car batteries](https://bateriasonline.es/en/car-batteries) → [Optima](https://bateriasonline.es/en/optima-batteries)

- **Canonical URL**: https://bateriasonline.es/en/optima-rtf-4-2
- **Language**: en
- **Brand**: Optima
- **Reference**: BOL-OPTIMA-RTF-4.2
- **EAN**: 4016987128237
- **MPN**: RTF-4.2
- **Price**: 200,57 € (VAT incl., Spain)
- **Last updated**: 2026-10-27

## Technical specifications

| Feature | Value |
|---|---|
| Brand | Optima |
| Range | OPTIMA RED TOP |
| Application | Cars |
| Technology | Spiral AGM |
| Voltage | 12 V |
| Capacity | 50 Ah |
| Cold cranking amps (EN) | 815 A |
| Length | 254 mm |
| Width | 185 mm |
| Height | 184 mm |
| Weight | 18 kg |
| Polarity | Positive terminal on the left |
| ETN code | 804250000 |

## Quick description

Optima RTF-4.2 (ETN 804 250 000, also written 804250000): car battery (spiral AGM) with 12 V, 50 Ah and 815 A cold cranking current, measuring 254 × 185 × 184 mm, with the positive terminal on the left.

## Description

## The Optima RTF-4.2 at a glance

The Optima RTF-4.2 is made for petrol and diesel cars without automatic engine stop. If your car has no Start-Stop and had a 50 Ah battery, the RTF-4.2 is a direct replacement.
At 50 Ah it covers petrol compacts and small diesels, the best-selling format in Europe. The RTF-4.2 belongs to the Optima OPTIMA RED TOP range. [More Optima batteries](https://bateriasonline.es/en/optima-batteries)

## Optima RTF-4.2 codes and part numbers

This is how the Optima RTF-4.2 appears on the label and in parts catalogues:

| Commercial reference | RTF-4.2 |
|---|---|
| ETN code | 804250000 (also 804 250 000) |
| EAN | 4016987128237 |
| Same ETN as | Optima RTU-4.2 |
| Case size according to Optima | 78 (BCI) |
| Base hold-down | B11 |
| Also known as | Optima 804250000 · Optima 804 250 000 |
| Not to be confused with | Optima RTC-4.2 (50 Ah, 815 A), Optima RTR-4.2 (50 Ah, 815 A, positive terminal on the right) |

## Optima RTF-4.2 vs RTS-3.7 and RTU-3.7: which one to choose?

The real differences between the RTF-4.2 and the closest Optima models:

| Model | Capacity | Cold cranking (EN) | Dimensions (mm) | Positive | Weight |
|---|---|---|---|---|---|
| Optima RTF-4.2 (this one) | 50 Ah | 815 A | 254 × 185 × 184 | left | 18 kg |
| Optima RTS-3.7 | 44 Ah | 730 A | 237 × 172 × 197 | left | 15.6 kg |
| Optima RTU-3.7 | 44 Ah | 730 A | 237 × 172 × 197 | left | 15.7 kg |

- Optima RTS-3.7: 6 Ah less, 85 A less cranking power, a different case (237 × 172 × 197 mm).
- Optima RTU-3.7: 6 Ah less, 85 A less cranking power, a different case (237 × 172 × 197 mm).

## Equivalents and alternatives to the Optima RTF-4.2

No other reference in the catalogue fully matches the dimensions and polarity of the RTF-4.2; you will find the closest ones among our [car batteries](https://bateriasonline.es/en/car-batteries).

## What it means that the RTF-4.2 is spiral AGM

Inside, the RTF-4.2 rolls its plates into cylindrical cells (spiral AGM). It is the basis of OPTIMA batteries.

## Check this before ordering the Optima RTF-4.2

- The RTF-4.2 is AGM: it replaces an AGM or an EFB of the same size. You can swap an EFB for an AGM, but not an AGM for an EFB.
- Check the EN amps on your battery: if it says 815 A or less, the RTF-4.2 covers your engine.
- With 50 Ah, the RTF-4.2 replaces an original battery of that capacity or slightly less.
- Polarity of the RTF-4.2: positive terminal on the left (if yours has it on the other side, the cables will not reach).
- The RTF-4.2 needs 254 × 185 × 184 mm of space: measure it with the hold-down clamp in place.

## Frequently asked questions about the Optima RTF-4.2

### Optima RTF-4.2 or RTS-3.7?

Compared with the RTF-4.2, the Optima RTS-3.7 has 6 Ah less and 85 A less cranking power. The RTF-4.2 cranks harder; the RTS-3.7 is only a good option if your original battery says 730 A or less. Mind the space: the RTS-3.7 measures 237 × 172 × 197 mm.

### What is the ETN code of the Optima RTF-4.2?

804250000, also written 804 250 000. The ETN (European Type Number) is printed on the label and used in parts catalogues.

### Can the Optima RTF-4.2 be used in a car with Start-Stop?

Yes. As an AGM battery, the RTF-4.2 handles automatic engine stop and brake energy recovery, and it can replace an EFB of the same size.

### How much does the Optima RTF-4.2 weigh?

The RTF-4.2 weighs 18 kg. For reference, the Optima RTS-3.7 (44 Ah) weighs 15.6 kg.

### Which side is the positive terminal on the Optima RTF-4.2?

The RTF-4.2 has the positive terminal on the left, looking at the battery from its long side with the terminals closest to you.

### Which charger does the Optima RTF-4.2 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.

## More batteries to compare with the RTF-4.2

- [All car batteries](https://bateriasonline.es/en/car-batteries)
- [Full Optima catalogue](https://bateriasonline.es/en/optima-batteries)

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