Xiaomi Mi Band 2 Smart Band: OLED Touch Screen with Heart Rate Monitor and IP67 Waterproofing

The Xiaomi Mi Band 2 is a feature-focused activity tracker designed to provide core fitness metrics in a lightweight, wearable format. Its central component is a 0.42-inch OLED touchscreen, which clearly displays real-time data such as heart rate readings, step count, and smartphone notifications. Powered by a 70mAh battery, the device is engineered for efficiency, offering up to 20 days of standby time on a single charge. Weighing only 7 grams and constructed from plastic and aluminium, the Mi Band 2 is built for all-day comfort. Its IP67 waterproof certification means it can resist sweat, rain, and accidental splashes, supporting an active lifestyle without requiring constant removal.

Core Technology and Performance

The Mi Band 2 integrates several key components to deliver its smart tracking functions. Its optical heart rate sensor sits on the underside of the device, allowing for on-demand or continuous pulse monitoring during activities.

Display and Interaction

The 0.42-inch OLED touchscreen is the primary user interface. It provides a clear, readable space to view heart rate data, step progress, and incoming call or message alerts. Interaction is managed through touch controls on the screen itself, eliminating the need for physical buttons on the band's face and contributing to its streamlined design.

Connectivity and Sensors

Device pairing and data sync are handled by a Dialog Bluetooth 4.0 BLE (Bluetooth Low Energy) chip, ensuring stable communication with compatible smartphones while conserving battery. Motion tracking is managed by an ADI ultra-low power acceleration sensor, which accurately records steps and general activity levels throughout the day.

Battery and Power Management

A 70mAh lithium polymer battery provides the power, supporting the claimed standby time of up to 20 days under typical use. Charging is done via a proprietary magnetic charger (included), which connects to ports on the back of the core module. The required input is 5V DC, with a typical charging current of 45mA.

Design, Fit, and Durability

Xiaomi has prioritised a practical, unobtrusive design for the Mi Band 2, making it suitable for continuous wear in various environments.

Materials and Build

The main tracker module is housed in a casing made from plastic and aluminium, giving it a light yet rigid structure. The wristband is made from a flexible thermoplastic elastomer, a material chosen for its skin-friendly feel and durability. The band secures via a buckle made from aluminium.

Size and Adjustability

The total wrist strap length is 235mm. It features an adjustable design, allowing users to secure it comfortably on wrists with circumferences between 155mm and 210mm. This adjustability, combined with the 7g total weight, ensures the band stays securely in place during movement without causing discomfort.

Water and Environmental Resistance

The IP67 rating is a key practical feature. The '6' denotes complete protection against dust ingress, while the '7' means the device can withstand immersion in up to 1 metre of fresh water for up to 30 minutes. This makes the band resilient to sweat during workouts, heavy rain, and accidental splashes, though it is not intended for swimming or high-pressure water activities.

Functionality and Compatibility

The Mi Band 2 serves as a comprehensive activity monitor and smart notification centre, with specific system requirements for full functionality.

Tracking and Monitoring Features

The primary functions include continuous optical heart rate monitoring, step counting via the pedometer, and sleep tracking. Users can also set silent alarms directly through the connected Mi Fit app, which vibrates the band at the set time.

Smart Notifications

When connected to a smartphone, the band can receive push notifications for calls, texts, and alerts from other apps. These notifications are displayed on the OLED screen, allowing users to check them discreetly without pulling out their phone.

System Requirements

For full functionality, the Mi Band 2 requires a smartphone running Android 4.4 or a later version, with hardware support for Bluetooth 4.0. The product information notes that phones with Android 5.0 or above are compatible.