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Need to reduce speed on 12VDC 400A motor

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Apr 26, 2022
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Hi Everyone,

I have a 12VDC winch that is rated at 400a. It is a brushed motor and it is already geared at 300:1. Problem is it is still to fast, even after I have a block and tackle installed. I would happily purchase a controller or drive, but have not been able to find one that is quickly available. 1/2 speed would be just about right, so I would also be happy with an option to simply fix a slower speed.

Thank you!


12V 400A is not a newbie project, thus I recommend to search for a ready to buy solution.
Generally a PWM with some 100Hz switching frequency should be sufficient.
For generating the PWM any microcontroller / arduino board will do. Even a non microcontroller solution is simple.


I have searched and have not been able to find a ready to buy solution.
I agree and have no problem generating a PWM, but dealing with that kind of load is where I need advise. What is the simple non microcontroller solution you are referring too?

Really 400A? Please show the type plate.
This is the winch. 25000lbs. Rated at 400A. With my amp clamp under this test load I am seeing about 155A.


I think 400 A is for maximum load. If you don't use the winch at maximum load then why don't you just find a power supply rated at a lower voltage?

The power supply is a car/truck battery. No means to reduce the supply voltage, except for operating the 24V winch from a 12V battery.

I'm not aware of a suitable low voltage MOSFET chopper or H-bridge module in the intendend current range. We used 3-phase bridges from Mitsubishi in the past, they could be used by paralleling phases.


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you can buy 500A choppers that run off 24VDC that will allow you to vary the power and hence speed of the winch ....

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