Li-ion Cell Charger with TP4056 and XIAO ESP32S3

Made a Li-ion 18650 Cell charger with onboard Voltage monitoring setup powered by XIAO ESP32S3 and SSD1306 Display

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This Li-ion cell charger features an incorporated XIAO ESP32S3-based battery voltage monitoring system that shows the battery's current voltage as measured by a simple voltage divider circuit.

We are using the well-known TP4056 Li-ion Charging IC to charge the Li-ion cell. We are utilizing a DC-DC Buck Module to supply a stable 5V to this circuit. It does this by converting the 12V input side to 5V 3A or QC3.0, which is plenty to power the Li-ion cell. Moreover, it contains a few USB ports that can be used to power XYZ devices.

Essentially, there are two primary applications for this device: first, it charges Li-ion cells, which is very helpful because I have a lot of fresh Li-ion cells that are stored for a long time.

Since their internal resistance decreases after more than four to five months, we can simply put any low-voltage cell in and charge it to its operating voltage. Second, it offers steady 5V via USB ports, which is sufficient to power XYZ USB devices.

fusion - 8.95 MB - 02/19/2024 at 07:09


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  • 1

    The process of designing the battery charger began with the making of a model for the circuit, which will include an SSD1306 screen and a Li-ion cell holder mounted on a 1.5 mm thick PCB.

    In addition, we had to model the circuit for the DC-DC Buck Module, which is mounted on the bottom side, and the main circuit on the top side.

    The concept was to use a 3D printed frame made out of a base attached to four mounting pillars, one of which had a holder for a rocker switch, to connect these two circuits together.

    Following the model's preparation, we used yellow PLA and a 0.4mm nozzle with 20% infill to 3D print each part of the frame.

  • 2

    Let's have a closer look at the circuit.

    It consists mainly of three sections: the XIAO ESP32S3 and SSD1306 display are connected via the XIAO MCU's I2C pins in the first section.

    The voltage divider part comes next, and it is made up of two resistors that are wired in series between the battery + port and GND. The D0 pin of the XIAO, which will be reading analog readings and showing analog values on a serial monitor, is linked to the middle connection of the voltage divide. These analog values will subsequently be converted into voltage values.

    The TP4056 setup is the third and most crucial element of this project. It is a commonly used Li-ion charging IC that is used when we only need to charge Li-ion or Li-Po batteries. Because of its overcharge and overdicharge protection features, the battery voltage is maintained between 2.5 and 4.2 V, which is the optimal range for lithium-ion batteries to operate in.

    We have added a CON2 port and paired it with a switch in series to charge the cell. The 5V/3A input of a DC-DC Buck coverter will be connected to the entire circuit. Li-ion cells will be charging with a maximum current of 1A due to TP4056, and this maximum current will decrease linearly with increasing battery voltage.

    After the schematic is complete, we use the board dimensions from the previously created circuit CAD file to create the project's PCB using PCB Cad software.

  • 3
    Seeed Fusion Service

    After finalizing the PCB and generating its Gerber data, I sent it to SEEED Studio for samples.

    The PCB was ordered in a black solder mask with white silkscreen.

    PCBs were received in a week, and their quality was super good considering the rate, which was also pretty low.

    Seeed Fusion PCB Service offers one-stop prototyping for PCB manufacture and PCB assembly, and as a result, they produce superior-quality PCBs and fast turnkey PCBAs within 7 working days.

    Seeed Studio Fusion PCB Assembly Service takes care of the entire fabrication process, from Seeed Studio Fusion Agile manufacturing and hardware customization to parts sourcing, assembly, and testing services, so you can be sure that they are getting a quality product.

    After gauging market interest and verifying a working prototype, Seeed Propagate Service can help you bring the product to market with professional guidance and a strong network of connections.

    Next is the PCB assembly process.

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