The Problem :

In robotics projects, especially those involving motors or multiple power sources (like battery + USB), you may face a common issue: reverse current. When current flows back into your power source, it can damage regulators, batteries, or microcontrollers—sometimes permanently. This is especially risky when using brushed motors or during sudden stops, where motors act like generators.

The Solution :

To protect your circuits, use a Schottky diode or a P-channel MOSFET. These components act as one-way gates—allowing current to flow into your system but blocking it from going backward. Schottky diodes are simpler but come with higher voltage drops; P-channel MOSFETs offer lower power loss, making them ideal for battery-operated bots.

Practical Example :

Let’s say you’re building an obstacle-avoiding robot. When the motor stops abruptly, it sends voltage spikes backward. Adding a P-channel MOSFET between the battery and your motor driver ensures any reverse current is blocked, saving your control board and power source.

Sample Calculation :

Assume your bot draws 2A.

With a Schottky diode (0.4V drop):

Power Loss = 0.4V × 2A = 0.8W

Using a MOSFET with R_DS(on) = 50mΩ:

Power Loss = (2A)² × 0.05Ω = 0.2W

That’s 4x more efficient—perfect for battery life!

Product Suggestion :

Check out these India-made components for your build:

• P-Channel MOSFET

• Schottky Diode

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