🔋 The Problem: Reverse Polarity in Battery Packs

Connecting a battery pack in reverse—even for a moment—can instantly damage your circuit. From blown regulators to fried microcontrollers, the cost of a simple polarity error can be high. This is a common mistake among beginners and even experienced prototypers working fast.

🔧 The Solution: Use a Reverse Protection Circuit

A basic fix involves adding a Schottky diode in series with the positive terminal. For more efficient designs, a P-channel MOSFET placed with the source to the battery’s positive terminal and the drain to the load provides near-zero voltage drop and automatic reverse protection.

💡 Practical Example

You’ve built a custom 12V lithium-ion battery pack for a portable speaker. Accidentally reversing the terminals while testing could destroy the internal amplifier module. Adding a P-MOSFET reverse protection circuit prevents power from flowing when polarity is wrong—keeping your components safe.

📐 Sample Calculation

If your circuit draws 2A and you use a Schottky diode with 0.4V forward drop:

Power loss = V × I = 0.4V × 2A = 0.8W.

Using a P-channel MOSFET with R_DS(on) = 30mΩ:

Power loss = I² × R = 4A² × 0.03 = 0.48W — more efficient and better for long-term use.

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Browse MOSFETs or Schottky Diodes, proudly Made in India.

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