mlab-modules / lion2cell01

Dual-cell Li-Ion Battery management system.

LION2CELL01D - Li-ion dual-cell Battery Management Module

Description

The LION2CELL01D is an integrated battery management solution for 18650 Li-ion batteries. It is designed to manage the charging, balancing, and monitoring of two series-connected Li-ion cells. This module measures the remaining energy, voltage, and temperature of the batteries, and protects against over-voltage and over-draining conditions.

Features

• Charging and Balancing: Supports charging, balancing, and termination with temperature protection.
• Gas-gauging: Temperature-compensated gas-gauging for accurate remaining energy estimation.
• Protection: Over-voltage, over-current protection, but no under-voltage protection (the module operates until battery depletion).
• Communication: Supports I2C and HDQ communication interfaces.

Technical Specifications

• Power Supply: 12 V @ 2 A
• Charging Current: Factory set to approximately 1.3 A
• Battery Holder: 2x 18650
• Interfaces: I2C, HDQ
• Integrated Circuits:
  • BQ24103 for charging
  • BQ34Z100 for fuel gauging
• Dimensions: 80.77 x 60.45 x 16 mm

Connection

Pin	Signal	Description
1	PG	Power Good
2	STAT2	Status Indicator
3	GND	Ground
4	CE	Chip Enable
5	STAT1	Status Indicator
6	CMODE	Configuration Mode

Construction

The module is constructed with three main functional blocks:

1. Charging Circuitry: Manages the charging process of the two series-connected Li-ion cells.
2. Measurement Circuitry: Measures the voltage, current, and temperature of the cells.
3. Balancing and Protection Circuitry: Ensures cell voltage balancing and provides protection against over-voltage.

Important Considerations

• Regular charging is required (at least once every six months) to maintain the batteries within operational voltage ranges.
• Specific resistor values and settings are used for the voltage measurement, ensuring accurate readings without exceeding voltage limits.
• The module is equipped with a balancing circuit that discharges one of the cells to match the voltage of the other, with a discharge current around 10 mA.

Setup and Configuration

1. Installation:

   • Check the PCB for proper soldering.
   • Insert the batteries in the designated order: position 1 first, followed by position 2.
   • Verify the operation of the charging function by connecting a 12V adapter.

2. Software:

   • Use setguage2cell.py to upload parameters to the energy measurement circuit.
   • Parameters are tailored for Panasonic NCR18650B or INR18650MJ1 cells; adjustments are needed for other types.
   • Conduct at least one charge/discharge cycle for accurate energy measurements.