Quick Specifications
| Model | BM21 |
|---|---|
| Accessories | Current shunt (sampler), shielded wire, display, butterfly nut |
| Application Scenarios | Golf cars, marine, RV, solar, backup power systems |
Quick Specifications
| Model | BM21 |
|---|---|
| Shunt Ratings | 75A / 150A / 500A |
| Display | Onboard LCD + Bluetooth smartphone app |
| App Metrics | Voltage, remaining capacity, current, power (W), SOC, cycle count, time remaining |
| Supported Chemistries | Lithium, Lithium-ion, Lead-acid, NiMH |
| Accessories | Current shunt (sampler), shielded wire, display, butterfly nut |
| Application Scenarios | Golf cars, marine, RV, solar, backup power systems |
Product Overview
The BM21 is a shunt-based smart battery monitor that keeps you informed about exactly what your battery is doing. An external shunt (75A, 150A or 500A) tracks charge and discharge current while a field-installed sense wire reads live voltage; the monitor computes amp-hours in and out so the onboard LCD always shows voltage, current, state of charge and total amp-hours at a glance.
Pair it with the Bluetooth smartphone app and you get the full picture: remaining capacity, power in watts, cycle count and estimated time remaining. It works across lithium, lithium-ion, lead-acid and NiMH chemistries, so a single monitor covers golf cars, marine banks, RV house batteries, solar storage and backup systems.
Core Features
- Shunt-Based Measurement: An external 75A/150A/500A shunt measures bidirectional current while the unit calculates amp-hour throughput.
- LCD + Bluetooth App: The onboard display shows voltage, current, SOC and total Ah; the app adds remaining capacity, power, cycle count and time remaining.
- Real-Time Voltage Sensing: A dedicated sense wire delivers accurate live voltage readings straight from the battery terminals.
- Multi-Chemistry Support: Compatible with lithium, lithium-ion, lead-acid and NiMH batteries — one monitor for mixed fleets.
- Complete Install Kit: Ships with current shunt, shielded wire, display unit and butterfly nut for straightforward installation.
Application Scenarios
From golf cars and utility vehicles to floor cleaning machines, aerial work platforms, marine vessels, RVs, solar installations and backup power, the BM21 gives operators and owners a reliable, always-visible window into battery health.
Frequently Asked Questions
How does the BM21 measure battery capacity?
The BM21 uses a precision shunt resistor with coulomb counting — it continuously measures current flowing in and out of the battery and calculates an accurate state of charge, far more reliable than voltage-only gauges.
Can I check the readings on my phone?
Yes. The BM21 has built-in Bluetooth and pairs with the smartphone app for live voltage, current, power, temperature and remaining capacity — useful when the battery is installed somewhere hard to reach.
Which shunt rating do I need?
Choose a shunt rated above your system’s maximum continuous current: 75A / 150A / 500A options cover most RV, marine and off-grid setups (larger ratings available on request). Running a shunt near its limit hurts accuracy, so leave headroom.
Do you offer wholesale pricing on the BM21?
Yes. JKBMS supplies the BM21 to battery pack assemblers, distributors and brands worldwide. Click Request a Quote above for wholesale pricing, OEM/ODM customization options and lead times.