Boost Your Raspberry Pi's Power: A Guide to Modifying LS-POE-B0525 PoE Splitters

Power over Ethernet (PoE) splitters like the LS-POE-B0525 offer a cost-effective solution for powering Raspberry Pi devices using 802.3af PoE. These splitters are particularly useful when the official PoE board isn't compatible with your setup, such as when using a custom case, a HAT, or an older Pi model without a PoE header. While these splitters are generally reliable and provide good value, they sometimes face voltage output challenges that can affect the Raspberry Pi's performance.

The LS-POE-B0525 PoE splitter, in its 5V configuration, outputs exactly 5.00 volts. However, due to the thin wires in the short cable, voltage drop occurs during transmission. This results in the Raspberry Pi receiving only about 4.8V under load, which can trigger undervoltage warnings. To address this issue, we can modify the splitter to output a slightly higher voltage, ensuring stable power delivery to the Pi.

To perform this modification, you'll need the following tools and materials: 1. A sharp knife or blade 2. A spudger or small screwdriver 3. Soldering iron and solder 4. A resistor (300K ohm recommended, but values may vary based on desired output) 5. Two-part epoxy or large heat shrink tubing 6. Safety glasses and ESD protection (recommended)

The first step is to carefully open the glued case of the LS-POE-B0525: 1. Use a sharp knife to slide along the existing gap in the case sides. 2. Make multiple passes, cutting deeper each time until you hear cracking sounds as the glue gives way. 3. Once the cut is deep enough, use a spudger or screwdriver to lever the case open. 4. Separate the case into two pieces and remove the circuit board.

On the back of the circuit board, locate the resistor marked R14. This resistor controls the output voltage. To increase the voltage, we need to add another resistor in parallel, increasing the overall current flow through this point. Instead of soldering directly to R14, which can be challenging due to its small size, we'll connect our new resistor to more accessible points that are electrically equivalent.

Solder the new resistor between these two points: 1. One side of capacitor C9 2. The lower leg of component U3 Ensure that the resistor is pressed flat against the PCB to fit within the case. A 1/4 watt resistor is sufficient for this low-current application and fits well in the available space.

The resistor value determines the increase in output voltage: - A 300K ohm resistor will increase the output to around 5.3V (no load) or 5.2V (under load). - This is slightly above the USB specification but generally works well with Raspberry Pi devices. - For a more conservative approach, use a higher resistance value. - Do not go below 300K ohm, as this could produce voltages that may damage devices or even cause component failure in the PoE adapter. - If you're also replacing the USB cable with one that has thicker wires, consider using a resistance higher than 300K ohm to compensate for reduced voltage drop.

After the modification: 1. Carefully reassemble the case, noting that it won't close completely without adhesive. 2. Use two-part epoxy or large heat shrink tubing to seal the case. 3. Proper reassembly is crucial for safety, as the PoE side can carry up to 60 volts during operation. 4. While the voltage is unlikely to cause serious harm, it's best to ensure the case is securely closed to prevent any potential shocks.

This modification can significantly improve the performance of your LS-POE-B0525 PoE splitter when used with Raspberry Pi devices. However, it's important to note a few key points: 1. This modification may void your warranty. 2. Be cautious with the voltage increase – staying close to the USB specification is advisable. 3. If you're uncomfortable with electronics modification, seek help from a professional. 4. Always prioritize safety when working with electrical components. 5. Test the modified splitter thoroughly before deploying it in your project. By following this guide, you can create a more reliable power solution for your Raspberry Pi PoE setup, potentially eliminating undervoltage issues and improving overall system stability.