How do I implement Reverse Polarity protection in PWM Charge controller.

[hassaan1309]

Hi friends. I am designing a PWM Solar Charge Controller as a hobby project. I want to keep its current rating to 25 Amperes. I am not sure about how can I implement reverse polarity protection in this charger. Please see the attached circuit (this is just a simple circuit to show what I am planning to do). If I think about using the diodes shown as DIODE-1 and DIODE-2 in the circuit, I am unable to find diodes with such high rating (25 A) in the market. Maximum available rating in general purpose diodes is 6A. Now which diode should I use here? Or is there any other way to implement reverse polarity protection here?
Please help me with your knowledge.

Thanks

 

[jamespond]

I think parallel diodes with normal fuses cause less power loss. At 25A the serial diodes constantly wants blowup and need huge heatsinks.



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I built one solar charger. It's work for me more than 3 years. I used switch mode for better efficiency.

 

[FvM]

Some questions:
- Polarity reversal of which side do you expect, solar panel, battery or both?
- It's not clear why you have two diodes?
- A PWM charge control would use a buck converter topology.
- I wonder how the MOSFET gate control voltage is generated with required level?

25 A diodes are of course available. But a PMOSFET can achieve input reverse polarity protection wit lower voltage drop.