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Description

Imported from GitHub: DavidVeloz95/Open-Source-Battery-Smart-Charger · commit 0707eb9 · license MIT

Description

Embedded power electronics project: intelligent 2S Li-Ion charger with protection, power switching and monitoring, designed in KiCad.

README

Open Battery Smart Charger

Smart 2S Li-Ion battery charger designed in KiCad featuring input protection, power-path management, and intelligent charging control.

Overview

This project implements an intelligent battery charging system for 2-cell Li-Ion batteries (8.4V) with integrated protection and automatic power switching.

The system combines:

  • Smart charging control
  • Input overvoltage and overcurrent protection
  • Automatic source/battery switching
  • Auxiliary regulated 3.3V rail
  • Battery monitoring interfaces

The design was developed in KiCad 10 as part of a hardware/electronics engineering portfolio project.

Features

  • 2S Li-Ion battery charging (8.4V)
  • Constant-current / constant-voltage (CC/CV) charging
  • Input surge and fault protection
  • Power-path management between external supply and battery
  • Reverse current protection
  • 3.3V regulated output for embedded systems
  • Thermistor input for battery temperature supervision
  • System and battery voltage interfaces

System Architecture

1. Input Protection Stage

The input stage is protected using the TPS26600 eFuse, providing:

  • Overvoltage protection (OVP)
  • Current limiting
  • Fault protection
  • Hot-plug robustness

This stage protects downstream electronics from abnormal supply conditions.

2. Smart Battery Charger

Battery charging is managed using the LT3650, configured for:

  • 2S Li-Ion battery charging
  • Constant-current / constant-voltage charging profile
  • Battery temperature monitoring
  • Charging status feedback

3. Power Path Management

The LTC4412 controller enables automatic switching between:

  • External DC power source
  • Battery supply

This ensures uninterrupted system operation while preventing reverse current paths.

4. Auxiliary Power Rail

A dedicated 3.3V LDO regulator powers low-voltage logic and embedded systems.

Main Components

ComponentFunction
LT3650Smart battery charger
TPS26600Input protection / eFuse
LTC4412Ideal diode power-path controller
LDK320AM33R3.3V voltage regulator

Specifications

ParameterValue
Battery Type2S Li-Ion
Charge Voltage8.4V
Charging MethodCC/CV
Logic Rail3.3V
Input ProtectionOVP / current limiting
Design ToolKiCad 10

Repository Structure

Open_Battery_Charger/
│
├── hardware/
│   ├── Open_Battery_Charger.kicad_pro
│   ├── Open_Battery_Charger.kicad_sch
│   ├── Open_Battery_Charger.kicad_pcb
│   └── fp-lib-table
│
├── docs/
│   ├── schematic.pdf
│   ├── schematic.png
│   ├── 2D_pcb_top.png
│   ├── 2D_pcb_bottom.png
│   ├── 3D_pcb_top.png
│   ├── 3D_pcb_bottom.png
│   ├── Detailed_Design_Procedure_LT3650.pdf
│   ├── Detailed_Design_Procedure_TPS2660
│   └── Open_Source_Battery_Smart_Charger_Specifications.pdf
│
└── production/
    ├── gerbers/
    └── bom.csv

Schematic

Schematic

PCB Design

Top View

PCB Top

3D Render

PCB Render

Design Considerations

Key engineering decisions considered during development:

  • Input fault protection for safer operation
  • Efficient battery charging profile implementation
  • Automatic power source switching
  • Low-voltage regulation for embedded systems
  • Modular architecture for maintainability

Tools

  • KiCad 10
  • Datasheet-driven design methodology
  • Electronic circuit validation

Future Improvements

  • PCB manufacturing and validation
  • Thermal characterization
  • Charging efficiency measurements
  • Test reports and oscilloscope captures
  • Firmware integration for battery monitoring

License

This project is released under the MIT License.

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