Solar Chager PowerBank - Charge Your Electronics With the Sun

The solar charger uses the energy from a solar panel to charge a Li-Ion rechargeable battery and provide an stable 5V - 0.6A output for any device you connect into the power bank

Link to the GitHub repository

Several components are used. You can check the Bill Of Materials attached with prices and references to every component in Mouser.

You will find all the components, links to the components, Gerber and simulations files in the GitHub Repository. I highly recommend you to order the PCB files to PCBWAY, as it was the company I used to build all the pcbs for this project.

We can separate this powerbank into four sections:

1. The Li-Ion battery charger, based in the BQ24210 IC. This parts gets the variable voltage of the solar panel and provides a charging curve to the battery.
2. Battery protection IC, based on the AP9214L. You may chose a different model depending on the battery you are using. Here I selected the AP9214L-AN-HSBR. This IC disconnects the battery from the circuit if sees any potential risk, such overcharge voltage, overcurrent, overdischarge... and so on.
3. Boost converter: Based on the TPS61085, boost the voltage from the battery up to 5V. It has a pretty good accuracy (+- 1.5%) and provides up to 0.6A. It is perfect for small electronic devices.
4. eFuse: The TPS259620DDAR is the main chip that disconnects the load in case of any malfunction: overvoltage, overcurrent, undervoltage... and so on. It protects the load from a problem in the circuit, but it also protects the circuit from an excessive load.

The PCB is a two layer board that can be ordered from PCBWAY. You can access all the schematics, simulations and Kicad files from the repository.

Solder paste can be applied with a syringe or stecil. Afterwars, the SMD components must be placed with the use of some tweezers. It can be soldered in a hotplate or using a heatgun. You need to have special care with the four smal ICs, as they are quite fragile.

Afterwards, all the TH components can be placed and soldered by hand. It is recommended to cut the leads from all the components.

Lastly, the battery should be soldered to the battery pads.

As soon as the solar panel gets power from the sun, the battery of the powerbank will start charging. The output is 5V and it is enabled when the battery is charged, with or without sun. The powerbank can be charged from the sun at the same time that is delivering any power from the output port. On top of that, we have several protections:

• Solar Panel
• Input voltage from 3V to 20V. It has over-voltage protection (OVP).
• NTC Sensor: The charging process is compatible with the JEITA temperature standard for Li-Ion batteries, limiting the charge of the battery depending of the temperature of it.
• Protection for short-circuit in the battery.
• Battery
• Overcharge Detection Voltage at 4.2V (25mV accuracy)
• Overcharge Hysteresis Voltage Range. (Release at 4.1V)
• Overdischarge Detection Voltage at 2.5V.
• Overdischarge Hysteresis Voltage Range. (Release at 3.0V)
• Discharge overcurrent detection voltage.
• Short current detection voltage.
• Note: You may want to select a different AP9214 configuration depending of your battery type. We have tested the AP9214L-AE-HSB.
• Output
• Voltage fixed at 5V +-1.5%
• Undervoltage protection.
• Overvoltage protection at 5.7V
• Overcurrent and shortcircuit protection (+1A). It will recuperate when the shortcircuit is released.

If you like this project and wants to support my work, you can follow me on instagram and youtube:

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