One of the most coveted features of highly efficient winches is having a low amp draw. This means that the winch will not sap too much power from your battery. However, you can’t take the features listed on the winch specs at face value.
There are many factors that affect the efficiency of a winch. The specs listed on a winch’s product description are all based on its performance at optimum situations. And the truth of the matter is that rarely are winching operations in optimum scenarios in the real world.
In simpler terms, your winch can only perform like how it is described if it is is a lab or in a perfect world. The same is true of how much amp your winch draws.
The truth of the mater is that your winch will draw more amps than listed. In fact, it will seldom, if not never, be as low as described by the winch’s manufacturer.
What Affects Amp Draw
Amp draw is the amount of current the winch uses depending on how arduously the winch pulls. This means that amp draw is affected by the hurdles that make the winch strain harder.
Layers of Wrap
When winches are rated for their strength and efficiency, they only have one layer of cable wrapped around their winch drum. The thing is, the more layers of cable around them, the weaker they become. They become inefficient by approximately 10% for every extra wrap of cable put on the winch drum.
It is highly suggestible to anchor your cable as far as possible from winch so as to release the drum from as much wraps of cable as possible.
Line Pull
The more load there is on your winch, the more amp it will have to draw to accomplish the task. As an example, we’ll use the WARN 9.5xp as a model. The following data was a result of a single wrap of cable on the winch.
Line Pull Amp Draw
0 71
2000 169
4000 248
8000 413
9500 482
If you have not yet formed a preference between a synthetic rope or a steel wire cable, see our article that compares the two. Or if you decide to replace your winch line, then see our basic, step by step guide.
Converting Horsepower to Amperes
Horsepower is the measurement of electric power equal to 746 watts. If you know the horsepower of your winch motor, you can theoretically have a near accurate estimate of its amp draw.
There are a lot of mathematical formulas floating around the internet as to how to to convert HP to amps. But the simplest one is:
Amps = (HP x 746W) Winch Efficiency V
Where HP = horsepower, W = watts, V = volts and Winch Efficiency is how efficient the winch is.
As an example, a 1HP motor that runs 90% efficiency and at 120 volts will have an amp draw of:
Amps = (1HP x 746W) 0.9 120V
Amps = 6.9 A
To find the amp draw of your winch, just enter its values in our amps to horsepower calculator.
