Efficient Method of Switching 50v at 25A?

Thread Starter


Joined Aug 11, 2009
I have a key switch which can handle 50v at 1A. I need to use it to switch 50v at 25 A. I understand that I can use a MOSFET to switch the higher amperage, but I understand they also burn voltage (voltage drop from source to drain).

Is there a more efficient method of switching the higher amperage? To my knowledge, there aren't any key switches which can switch this much power. I wasn't able to find a relay which can handle this much current either.



Joined Oct 15, 2009
I would just go to a junk yard and get a 12vdc selenoid off a ford starter.
Not if you were required to meet any standards or didn't want to hold any liability. Most automotive stuff like that is only rated to 32V max or less. That is not sufficient for 50V applications. Will it work.. Most likely.. Is it correct.. No


Joined Aug 30, 2007
Also, a solenoid from a starter isn't rated for continous duty, and the OP hasn't given us that information yet.


Joined Oct 18, 2011
If you are hot swapping a load I would stay away from relays or any other mechanical device as this will ruin the contacts. Select some high power FETS and place them in parallel if needed to get the required current.


Joined Jun 7, 2009
depends on your application. A 'key' switch in industry means a 'safe' circuit, relay required, as solidstate switches are not considered 'safe'. Relays can and do switch heavy loads.