Li-ion Charger - Hardware details

Pinout

Li-ion Battery Charger pinout diagram

Li-ion Battery Charger with protection pinout diagram

Pin Details

Pin Marking	Pin Name	Description
VCC	Power In	Connect to 5V USB-C power input.
GND	Ground	Common ground.
BAT+	Battery +	Connect to the positive terminal of a single-cell Li-ion cell.
BAT-	Battery -	Connect to the negative terminal of the battery.

ℹ️

In addition, the Li-ion Battery Charger with protection board has these pins.

Pin Marking	Pin Name	Description
OUT+	Output +	Regulated output voltage (same as battery voltage).
OUT-	Output -	Output ground.

ℹ️

These boards are designed for 3.7V Li-ion or Li-Po single-cell batteries.

⚠️

For older Li-ion charger with protection boards, connect the TEMP pin to GND to initiate charging. The onboard CHRG LED will indicate the charging status.

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Dimensions

• Board Dimensions: 25 × 19 mm (0.98 × 0.75 inch)
• USB Connector: USB-C female
• Mounting holes: None (breadboard-compatible)

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LEDs

LED Name	Color	Meaning
CHRG	Red	Charging in progress
FULL	Blue	Battery fully charged

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Hardware repository

The hardware design files for these modules are available on GitHub:

Li-ion Charger Hardware Repository

Schematics and PCB layout for the charger module

Li-ion Charger with Protection Hardware Repository

Schematics and PCB layout for the charger module

The hardware repository contains everything you need to understand, modify, or manufacture the board. The various output folders are versioned. You can check which board version you have specifically by finding the version mark on the PCB.

Below is an overview of the available files.

CAD files

We use KiCad, an open-source PCB design tool. You can open and edit the .kicad_pro project file, which includes both the schematic and PCB layout.

The PANEL files are used internally for production.

Schematic

The OUTPUTS folder contains the schematic in .pdf format, exported from KiCad.

BOM (Bill of Materials)

The bill of materials (BOM) is provided in two formats:

• A standard .csv table, listing all components, part numbers, and values.
• An interactive BOM (.html) that visually highlights each component on the PCB, making it easy to locate and reference parts.

3D files

A 3D model of the PCB is available in .step format, allowing you to inspect the board design in CAD software.

Gerber files

Gerber files are essential for PCB manufacturing, as they contain precise instructions for each layer of the board. The repository includes standard Gerber outputs in a .zip file, such as:

• Copper layers (.Cu.gbr) – Defines the traces and pads on the board.
• Solder mask layers (.Mask.gbr) – Specifies the protective solder mask.
• Silkscreen layers (.Silkscreen.gbr) – Contains text and component markings.
• Paste layers (.Paste.gbr) – Used for stencil fabrication in SMD assembly.
• Drill files (.drl) – Provides drilling coordinates for vias and holes.
• Board outline (.Edge_Cuts.gbr) – Defines the shape of the PCB.
• Gerber job file (.gbrjob) – Describes the set of Gerber files used for production.

These files are ready for fabrication and can be used in PCB manufacturing.

Compliance

The Compliance section includes important regulatory and safety documentation for this product. These files ensure compliance with relevant industry standards and legal requirements.

• CE – Certification document confirming compliance with EU safety, health, and environmental requirements.
• UKCA – UKCA (UK Conformity Assessed) certification for the UK market.
• Safety Instructions – Safety guidelines and precautions are provided in English and German.
• Info.txt – Contains product details such as SKU, country of origin, HS tariff code, and barcode.