What I particularly like
It supports all voltages from 5 to 24 volts, which makes it extremely flexible. As a tinkerer, you usually have some spare components lying around, so this module is quite universal. I am also a big fan of screw terminals for wiring—no soldering or large connectors needed. It supports both a single 18650 cell or any other cell with a PH2.0 connector. Nowadays, you can get individual cells with 10,000 mAh; that's enough to power quite a few devices. Also, the free choice between USB and simple power outputs convinced me; in my view, it hardly gets better than this.
What is it exactly?
The module is an MPPT charge controller (Maximum Power Point Tracking) designed for small solar setups. It's perfect for using solar panels of about 5 V (or higher) to charge lithium batteries such as 18650 cells. It offers practical features: multiple inputs, protection functions (e.g., against overcharge or deep discharge), and flexible outputs. According to the product description, it is especially versatile regarding compatibility with solar panels—and this was confirmed in my tests.
For Arduino, ESP32, or Meshtastic projects, this device is super interesting: it provides stable 3.7 V or 4.2 V to charge a 18650 cell or battery pack and powers your project as long as enough solar energy is available.
My experience: What can the module do?
I tested the module under realistic conditions and was sometimes genuinely surprised:
Works even in low light
Even at dusk or under thick cloud cover, the controller charged reliably when I connected a 5 V solar panel. The MPPT algorithm seems really good and extracts energy even under weak light. This was a big plus for me because many modules only work well in bright sunshine. I hope to build a winter-proof Meshtastic node and will report on whether it lasts through winter.
Flexible power supply
You can plug a single 18650 cell directly into the board, and the charging current is automatically regulated. Alternatively, you can connect an external battery pack via a PH2.0 connector. This flexibility is great if you want to use larger batteries or expand your setup later.
From doubt to conviction
Like many tinkerers, I was initially skeptical: cheap price, no known manufacturer—does it really deliver? My tests had minor disappointments, but overall the module convinced me. The charging performance was stable, protection functions seemed to work, and the module proved robust even in changing weather. After a few weeks in operation, I see it as a reliable solution for projects aiming for independence from the power grid.
The catch: constantly lit LEDs
A minor downside: the module has LEDs that are always on. In my view, this is unnecessary power consumption, especially if you're building a low-power project. But no worries: the LEDs can be removed fairly easily by desoldering if you want to save every microamp. I did this in a test setup without affecting functionality.
Where the module shines
The module is ideal for a range of projects, particularly combined with Arduino, ESP32, or Meshtastic:
- Solar-powered sensors or weather stations: An ESP32 with sensors running on a solar panel gets reliably supplied—even in poor light or partial shading.
- Meshtastic or Meshcom nodes: For radio networks meant to operate autonomously, the MPPT controller ensures nodes always have power.
- Long-term outdoor projects: Wherever you want minimal maintenance (e.g., battery replacement), a smart charge controller like this is invaluable.
- Experiments with changing batteries: Thanks to the flexibility with 18650 cells or bigger battery packs, the module is great for prototypes where you want to stay flexible.
Tips for use
- Proper wiring and solar cells: Even the best MPPT controller can't help if the solar cells or cables are poor quality.
- Remove LEDs: In low-power projects, it’s worth desoldering the LEDs to reduce self-consumption.
- Measure charging current: Use a multimeter or data logger to check charging current under different lighting. This helps you understand how well the module performs in your environment.
- Consider heat: If the module is housed or exposed to direct sunlight, ensure adequate cooling.
Conclusion
The Solar MPPT charge controller B0F4QZ1KMK really convinced me—especially given its low price. For Arduino, ESP32, or Meshtastic projects, it's a solid and flexible solution, even though you should keep an eye on small quirks like the LEDs. With some fine-tuning, it's perfect for anyone building energy-autonomous projects.