What to Consider When Choosing an Electric Fence Energizer?

Selecting the right energizer for your farm is crucial to making an electric fence work for you. In order to make the electronic fence energizer fully play its role, we must choose according to the actual situation of the electronic fence. Here are some things to consider when choosing an electronic fence energizer.

The first step in selecting an energizer is to determine your power source. If the fence is close enough, an energizer that plugs into the hydro is often the cheapest and easiest solution. As the fence gets further away from an outlet, running wires become expensive and other power options start to look more attractive.

Deep-cycling 12 volt marine batteries are another potential power source for an energizer. These work best when you have at least two to swap out-one battery can charge while the other powers the energizer.

An energizer being powered by batteries needs to be fairly accessible so that batteries are easy to change before they run down. For electric fences in more remote locations, a solar panel may be the best solution. These tend to be the most expensive power source for a fence, but because the panel recharges the battery, it’s less likely to lose power than batteries alone. For solar panels to be effective, they need to receive a minimum of 4-6 hours of direct sunlight every day.

An electric fence is a psychological barrier: livestock learns not to touch the fence because the shock is unpleasant. Untrained animals or a non-electrified fence may enable livestock to go right through the fence.

Volts are a measure of electric potential. If we draw a comparison with water, voltage is akin to water pressure. See Table 1 for minimum output voltages. Check that the energizer can deliver an appropriate amount of voltage.

Energizers are rated in joules, which is a unit of energy. Your energizer must put out enough energy to deliver the right voltage along the entire fence.

Imagine a drip irrigation line. To be effective at watering plants, you need a high enough flow rate and water pressure to meet the water needs of whatever is at the far end of the line. The more holes you have in that drip tape, the less water will make it to the end. Those holes are comparable to weeds, tall grass, and branches touching your electric fence. They drain energy from the fence, reducing the voltage it delivers. This is called loading.

Your energizer must deliver enough joules to overcome the load and provide enough voltage along the length of the fence.

Measuring and energizer’s size in acres gets even less useful when you think about the different lengths of cross fencing it might have to power, so it’s probably best to ignore acreage numbers on an energizer.

The other point to bear in mind is that energizers power miles of wire, not offense. If you have a single-strand fence that goes five miles, it requires much less power than a five-strand fence going five miles, because the multi-strand is actually 25 miles of wire. Many manufacturers claim their energizers can power 8-20 miles/joule of output, but these are numbers obtained under ideal laboratory conditions.

In practice, if you have a one- or two-strand fence that is free from weeds, tall grass, and branches touching it, you might get 3-6 miles/joule. Under heavy loads (lots of debris touching your fence), you might only get 1 mile/joule. If you’re powering a multi-strand sheep fence, you might want a ratio of 0.16-0.33 miles/joule (between 3 and 6 joules per mile) to accommodate the high number of wires and the insulation value of wool.

There are two different energy ratings you might see on the box. Output joules indicate the amount of energy sent through the fence. Stored joules are the amount of energy in an energizer’s capacitors-multiply stored joules by 0.7 to get an estimate of the output.

If the energizer is plugged into an outlet, it’s receiving 120 V of electric potential (that’s your water pressure). If batteries or a solar panel is providing the power, likely the input voltage will be a multiple of 12V. However, the output voltage is much higher-probably over 3000 V. The energizer contains a transformer, which creates that increase in electric potential.

Capacitors store the higher electric potential and release it in pulses to the fence. Think of a tippy bucket at a water park. A small amount of water flows into the bucket, but once it gets full the bucket dumps the water out, rights itself, and starts collecting again. Capacitors build up electric potential and "dump" higher voltage down your fence line.

However, not all the water in a tippy bucket gets dumped; there’s a little residual in the bottom when the bucket starts to refill. Capacitors have a similar residual, which is why stored joules are about 30% more than output.

When in doubt, buy a bigger energizer. This is a point where it pays to think ahead. If there is a chance you will add to your electric fence in the future (either by fencing other fields or subdividing existing paddocks), factor in how many more output joules you will require, and buy an energizer that can handle that future load.

 

As an experienced manufacturer of electric fence products, HPS Fence focuses on providing professional technical solutions for small electric farms and home backyards. We can provide customers with sufficient product inventory to ensure customers' order requirements and timely delivery. We have established a comprehensive quality inspection system to control the quality of our products. If you are interested in our electric fence energizer, please contact us immediately!