# Motobatt MBTX20U · Motorcycle battery 12V 21Ah 310A

![Motobatt MBTX20U · Motorcycle battery 12V 21Ah 310A](https://bateriasonline.es/3258-home_default/motobatt-mbtx20u.jpg)

> Motobatt MBTX20U: 21 Ah motorcycle battery, 310 A (EN), 175×87×155 mm, AGM. Equivalent to Varta YTX20H-BS and Varta YTX20HL-BS.

**Category:** [Motorcycle batteries](https://bateriasonline.es/en/motorcycle-batteries) → [Motobatt](https://bateriasonline.es/en/motobatt-batteries)

- **Canonical URL**: https://bateriasonline.es/en/motobatt-mbtx20u
- **Language**: en
- **Brand**: Motobatt
- **Reference**: BOL-MOTOBATT-MBTX20U
- **MPN**: MBTX20U
- **Price**: 146,02 € (VAT incl., Spain)
- **Last updated**: 2026-11-09

## Technical specifications

| Feature | Value |
|---|---|
| Brand | Motobatt |
| Range | MOTOBATT QUADFLEX |
| Application | Motorcycles |
| Technology | AGM |
| Voltage | 12 V |
| Capacity | 21 Ah |
| Cold cranking amps (EN) | 310 A |
| Length | 175 mm |
| Width | 87 mm |
| Height | 155 mm |
| Weight | 6.5 kg |
| JIS code | YTX20 BS YTX20 LBS YTX20 HBS YB16 B YB16 LB YB16 CLB |

## Quick description

The Motobatt MBTX20U is a motorcycle battery (AGM) with 12 V, 21 Ah and 310 A cold cranking current, measuring 175 × 87 × 155 mm.

## Description

## Who the Motobatt MBTX20U is for

The Motobatt MBTX20U is a motorcycle starter battery: compact, vibration-resistant and with just the right power to turn the starter motor and feed the electronics. It handles frame vibration and idle periods better than an adapted car battery.
At 21 Ah it is a large battery for heavy motorcycles, jet skis and utility quads. The MBTX20U belongs to the Motobatt MOTOBATT QUADFLEX range. [See all Motobatt batteries](https://bateriasonline.es/en/motobatt-batteries)

## Part numbers and codes for the Motobatt MBTX20U

The MBTX20U is listed under these codes on labels, in garages and in catalogues:

| Commercial reference | MBTX20U |
|---|---|
| Not to be confused with | Motobatt MBTX24U (25 Ah, 300 A), Motobatt MBTX30U (32 Ah, 385 A) |

## Equivalents and alternatives to the Motobatt MBTX20U

Other AGM batteries that fit the MBTX20U's tray with the same polarity: an AGM can only be replaced by another AGM.

| Model | Technology | Capacity | Cold cranking (EN) | Dimensions (mm) |
|---|---|---|---|---|
| Varta YTX20H-BS | AGM | 18 Ah | 320 A | 175 × 87 × 154 |
| Varta YTX20HL-BS | AGM | 18 Ah | 320 A | 175 × 87 × 154 |
| Varta TX20H (FA) | AGM | 18 Ah | 310 A | 176 × 89 × 154 |
| Varta TX20HL (FA) | AGM | 18 Ah | 310 A | 176 × 89 × 154 |
| Motobatt MBTX20UHD | AGM | 21 Ah | 310 A | 175 × 87 × 155 |

## Motobatt MBTX20U vs MB18U and MB16U: which one to choose?

How the MBTX20U compares with Motobatt batteries of similar size and capacity:

| Model | Capacity | Cold cranking (EN) | Dimensions (mm) | Weight |
|---|---|---|---|---|
| Motobatt MBTX20U (this one) | 21 Ah | 310 A | 175 × 87 × 155 | 6.5 kg |
| Motobatt MB18U | 22.5 Ah | 280 A | 180 × 90 × 162 | 6.8 kg |
| Motobatt MB16U | 20 Ah | 240 A | 160 × 90 × 161 | 5.9 kg |

- Motobatt MB18U: 1.5 Ah more, 30 A less cranking power, a different case (180 × 90 × 162 mm).
- Motobatt MB16U: 1 Ah less, 70 A less cranking power, a different case (160 × 90 × 161 mm).

## What to look at before buying the MBTX20U

- Cold cranking: 310 A (EN), equal to or higher than the original.
- With 21 Ah, the MBTX20U replaces an original battery of that capacity or slightly less.
- Length, width and height of the MBTX20U: 175 × 87 × 155 mm.

## Frequently asked questions about the Motobatt MBTX20U

### MBTX20U or MB18U: which one suits me?

Compared with the MBTX20U, the Motobatt MB18U has 1.5 Ah more and 30 A less cranking power. The MBTX20U cranks harder; the MB18U is only a good option if your original battery says 280 A or less. Mind the space: the MB18U measures 180 × 90 × 162 mm.

### How much does the Motobatt MBTX20U weigh?

6.5 kg, with 21 Ah of capacity. For reference, the Motobatt MB18U (22.5 Ah) weighs 6.8 kg.

### Which battery is equivalent to the Motobatt MBTX20U?

Only other AGM batteries with its dimensions and polarity: Varta YTX20H-BS, Varta YTX20HL-BS and Varta TX20H (FA). Neither an EFB nor a conventional battery replaces the MBTX20U.

### How do I stop the motorcycle battery going flat in winter?

Connect it to a maintenance charger or disconnect it if the bike will sit for more than a month. A flat motorcycle battery sulphates in a few weeks.

## Inside the MBTX20U: AGM technology

The MBTX20U is AGM: the electrolyte is absorbed in glass fibre mats, so it is sealed and spill-proof. It withstands many more cycles than a conventional lead battery, at the cost of being more sensitive to overcharging.

## Keep comparing: alternatives to the MBTX20U

- [All motorcycle batteries](https://bateriasonline.es/en/motorcycle-batteries)
- [Full Motobatt catalogue](https://bateriasonline.es/en/motobatt-batteries)
- [Varta YTX20H-BS](https://bateriasonline.es/en/varta-ytx20h-bs-518908032) · 18 Ah, 320 A, 175×87×154 mm
- [Varta YTX20HL-BS](https://bateriasonline.es/en/varta-ytx20hl-bs-518918032) · 18 Ah, 320 A, 175×87×154 mm

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