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Since our drone platform is built from the Hexsoon EDU-650 frame kit, a custom power distribution board (PDB) was included with the system. Instead of replacing the professionally-made PDB, we decided to implement another function that is critical to our project: battery voltage monitoring.

Ensuring that a LiPo battery is within its operating voltage range is a safety-critical application. The safety requirement of the operating voltage for a LiPo battery is between 3.2V/cell and 4.2V/cell. The ideal operating voltage per cell for a LiPo battery is around its nominal voltage of 3.8V/cell. Overvolting (some cell has a voltage greater than 4.2) and undervolting (some cell has a voltage less than 3.2V) cause permanent damage to the battery, reduce its lifespan and make it susceptible to volatile behavior such as smoking or catching fire. However, overvolting a battery can only happen during charging and we rely on good quality chargers that balance the battery while charging. Hence, we will focus on preventing undervolting.

Our team is planning on making a printed circuit board (PCB) that can do the following:

• Detect the voltage of each cell in a 6 cell (6S battery)
• Provide a visual and an audible alarm when any cell reaches below 3.2V
• Have an LED display that shows the current voltage of each cell and total battery voltage in rotation.

Schematic

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