XD-82B 12V 4-LED Battery Level Capacity Indicator Module

XD-82B 12V 4-LED Battery Level Capacity Indicator Module is a compact 4-stage visual battery state-of-charge (SOC) monitor board built around the precision LM339 quad voltage comparator IC and an onboard voltage reference regulator. Equipped with four color-coded indicator LEDs (Red = 20%, Yellow 1 = 50%, Yellow 2 = 80%, Green = 100%), it provides an instant bar-graph readout of remaining charge for 12V lead-acid and 3S lithium-ion battery packs.

Key Features:

• 4-Stage Color-Coded LED Bar Graph: Four onboard SMD LEDs illuminate progressively as battery voltage rises — Red (20%), first Yellow (50%), second Yellow (80%), and Green (100%).
• Precision LM339 Quad Comparator Architecture: Uses an onboard voltage regulator reference and resistor divider ladder with an LM339 quad comparator for repeatable voltage threshold switching across temperature changes.
• Simple 2-Wire Hookup (`IN+` / `IN-`): Connects directly across any 12V battery or power rail with reverse-polarity protection diode.
• Expansion Test Header & Mounting Holes: Breaks out comparator test pins on a 2.54mm header alongside two M3 PCB mounting holes for panel or chassis installation.
• Ultra-Compact Footprint: Measures just ~35mm × 19mm for easy embedding on robot chassis, solar charge boxes, and portable power packs.

Technical Specifications:

• Model: XD-82B 12V 4-LED Battery Indicator
• Comparator IC: LM339 Low-Power Quad Voltage Comparator
• Nominal Battery Voltage: 12V DC (12V Lead-Acid / 3S 11.1V–12.6V Li-ion)
• 4-LED Threshold Representation: Red LED = 20% | Yellow LED 1 = 50% | Yellow LED 2 = 80% | Green LED = 100%
• Operating Current: ~15 mA (All 4 LEDs Illuminated)
• Operating Temperature Range: -40°C to +85°C

Mechanical Specifications:

• PCB Material: FR-4 Double-Sided Red/Blue Fiberglass PCB
• Mounting: 2 × 3mm Mounting Holes
• Terminals: 2-Pin Power Header (`+` / `-`) + Multi-Pin Comparator Test Header

Dimensions:

• Length: ~35 mm
• Width: ~19 mm
• Height: ~5 mm
• Weight: ~3.5 g

Pinout and Wiring:

• + (VCC / Battery+): Connect to 12V battery positive terminal (optionally wire through a momentary push-button switch so the LEDs only draw current when pressed).
• – (GND / Battery-): Connect to 12V battery negative terminal.

Datasheet Reference:

• Primary IC Datasheet: LM339 Quad Differential Comparator Datasheet (PDF)

Commonly Used in:

• 12V SLA / AGM Solar & Inverter Battery Boxes
• 3S 11.1V / 12.6V 18650 Robotics & Rover Battery Packs
• 12V Agricultural Sprayers, Camping Lanterns, and Portable Audio Boxes
• Educational Comparator & Voltage-Divider Demonstrations

Applications:

• Provides an at-a-glance 20% / 50% / 80% / 100% fuel gauge on 12V mobile robots, solar generator boxes, and backup UPS units.
• Wires in series with a panel-mount momentary push button for zero-standby-drain battery level checking.
• Allows students to probe individual LM339 comparator outputs via the auxiliary pin header.

Equivalent Models:

• 3S 12V Lithium Battery 5-LED Level Indicator Module: Push-button activated 5-LED 12V lithium battery level indicator with pre-soldered wire leads.
• 4S 16.8V BMS Li-ion Battery Lithium Battery Capacity Indicator: Panel-mount 4-bar blue/red LED battery capacity indicator for 4S (14.8V/16.8V) packs.

Package Includes:

• 1 × XD-82B 12V 4-LED Battery Level Capacity Indicator Module