Understanding Winch Amperage

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Last Updated on June 25, 2022

Low amp draw is one of the key aspects of the best winches. The winch drains a lot of energy from your battery. A winch with a low amp draw will use much less electricity. However, you must keep in mind that whatever capabilities are described in the winch’s product information may not always be delivered. 

In fact, the winch will continue to demand more amps than specified. Your winch can only perform as advertised in an ideal world or in a lab. Customers one of the most commonly asked questions is “how many amps their specific winch draws” and the answer to that question is my topic for this article.

Understanding Winch Amperage

Factors That Affect Amperage Draw

The quantity of current, used by the winch is determined by how hard the winch pulls. This implies that the challenges that make a winch strain harder have an impact on amp draw. Here are some key factors that highly affect the amount of amp drawn during winching.

1# Number Of Cable Layers

Winch manufacturers wrap only one layer of cable on and around the winch drum to test and rate them for efficiency and strength. The problem is that the winch tends to pull weaker with every new layer of cable wrapped on the drum. That directly affects amp draw.

The performance will drop about 10% for every single additional wrap of the cable. It is highly recommended that you anchor the cable as far away as possible from the winch, in order to free the drum from getting additional layers. That way your winch will perform efficiently.

2# Line Pull

The higher the weight on your winch, the more amps it will need to complete the task. We’ll take the WARN 9.5xp model as an example. The following data was obtained from a single cable wrap on the winch drum.

Line PullAmp Draw

In the comparison table, you can clearly see the rapid growth of amp draw as soon as the weight increases. It’s a simple fact actually, higher load means difficult to pull, thus the extra effort.

Understanding Horsepower To Amperes Conversion

The term “horsepower” refers to a unit of electric power equivalent to 746 watts. If you know how much horsepower a particular winch motor produces, you can calculate its amp draw rather accurately.

There are numerous mathematical methods available on the internet for converting HP to amps. I have seen most of them and the one I think is the simplest is given below:

Amps = (Horsepower x 746) / Efficiency / V

Here, V = Volts and Efficiency rate will be provided as a percentage, you will have to divide that by 100 and use the value.

For example, let’s say you have a 1 HP motor that works with 90% efficiency, and it needs 120 volts to run. Now, let’s calculate the amp draw of that winch motor: 

Given, Efficiency = 90 / 100 = 0.9 and V = 120


Amps = (1 x 746) / 0.9 / 120

Amps = 6.9 A

So, the amperage draw for that winch motor is 6.9 ampere. You can easily calculate the amp draw of any winch motor using that simple equation. You just have to perform some multiplication and division in your calculator.

I hope that you have a much better understanding of amperage draw now that you have read this article.

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About the Author: Brian Silvestro

Brian Silvestro is the founder and chief editor of OffroadersArena. He spends his free time tending to his BMW iX SUV and explaining its merits to anyone who'll listen.

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