The BM21-500 Smart Battery Monitor is a high-precision meter that allows you to check the status of your battery via the monitor display or your smartphone with the Smart Battery Monitor app. Through the use of the current shunt, the battery monitor measures the discharge or recharge currents and calculates the Ampere-hours (Ah) going in and out of the battery. High-precision voltage measurements are taken and displayed in real-time through the use of a field-installed sense wire.

The BM21-500 monitor is compatible with all types of batteries, especially Lithium-ion batteries


  • Battery Monitoring: The BM21-500 allows you to monitor the voltage, current, and overall health of your battery.
  • Bluetooth Connectivity: It comes equipped with Bluetooth technology, enabling wireless communication between the battery monitor and your smartphone.
  • Real-time Data: The battery monitor provides real-time data on the battery's performance, allowing you to stay informed about its status at all times.
  • Voltage Measurement: You can measure the battery's voltage accurately, helping you determine if it's fully charged or if it requires charging.
  • Current Measurement: The device can measure the current flowing into or out of the battery, helping you assess the battery's usage and charging status.
  • Capacity Monitoring: It allows you to monitor the remaining capacity of the battery, giving you an estimate of how much charge is left.
  • Health Analysis: The battery monitor analyzes the battery's health and provides information on its overall condition, such as the state of charge, state of health, and internal resistance.
  • Alerts and Notifications: You can set up customizable alerts and notifications to receive warnings when the battery voltage is too low, the current exceeds a certain threshold, or other relevant conditions are met.
  • Historical Data: The device stores historical data, allowing you to review and analyze the battery's performance over time.
  • User-Friendly Interface: The battery monitor features an intuitive interface, making it easy to navigate through the settings, view data, and customize preferences.
  • Compact and Portable: With its round shape and compact design, the battery monitor is easy to install and carry around.
  • High Amperage Support: The device can handle high currents of up to 500A, making it suitable for monitoring batteries in various applications, such as automotive, marine, or industrial.
  • Compatibility: The battery monitor is compatible with a wide range of battery types, including lead-acid, lithium-ion, AGM, gel, and more.
  • App Integration: It integrates with the Smart Battery Monitor app, allowing you to access and control the battery monitor's functions conveniently from your smartphone.
  • Data Logging: The battery monitor can log data over extended periods, enabling you to track long-term trends and identify any issues or patterns.


  • 1 x Smart Bluetooth LCD Display. Approx 59mm OD
  • 1 x 350 Amp (Cont.) - 500 Amp (Peak) Shunt
  • 1 x 1m Extension Cable
  • 1 x 1m Fused Battery sense wire
  • 1 x Square plastic mounting plate/li>
  • 1 x Mounting hardware

Displayed Data:

  • Battery Capacity - Indicator
  • Battery Voltage - Indicator
  • Battery Current - Indicator
  • Battery State of Charge (SOC)% - Indicator
  • Charge & Discharge - Indicators

500A Shunt Specs:

Specs Min Type Max Unit
Working Voltage 8.0   80.0 Volts
Working Disspation 10.0   12.0 mA
Standby Dissipation 0.5   0.8 mA
Sleep Dissipation 50.0   60.0 uA
Capacity Accuracy   +/- 1.0   %
Voltage Accuracy   +/- 1.0   %
Current Accuracy   +/- 1.0   %
Backlight On Current 40.0   50.0 mA
Backlight Off Current 40.0   40.0 mA
Capacity Setting Value 0.1   999 Ah
Sampler Working Current 50.0   500. A
Temperature Range 0 20 35 Degree C
Weight 65.0 grams
Size 59x20 mm
SKU EJ.BM21-500
Model # BM21-500
Shipping Weight 0.0650kg
Shipping Width 0.059m
Shipping Height 0.020m
Shipping Length 0.059m
Shipping Cubic 0.000070000m3
Unit Of Measure ea

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