Farmers and ranchers need to select a fence charger that will deliver enough power to consistently provide the electric pulse necessary regardless of the size of the fenced area, the type of cow or cattle or the ground conditions surrounding the fence.

Installing the wrong type of fence charger can lead to:

  • Inconsistent delivery of electric shock
  • Inadequate strength of the electric shock that is delivered
  • Injury of livestock
  • Cows, cattle and other livestock damaging the fence
  • Lack of electrical current in an area with heavy weeds or consistent power outage

Different types of electric fence chargers

The market place is filled with fence chargers offering a wide array of solutions. Consider these facts when selecting the right fence charger to adequately and safely contain your cows, cattle and other livestock.

  • Different power source options offer a variety of fence chargers to choose from based on whether you will use a plug-in, battery-operated or solar-powered fence charger.
  • Strength of the fence charger is different based on the size of the fenced property and the type of livestock that will be contained or deterred.
  • Impedance technology offers additional choices based on the ground and weather conditions of the property.

Not all fence chargers are made the same or offer the same consistent electric current depending on the conditions around and under the fence. You need to consider several different elements when selecting the right fence charger for your electric fencing needs.

Of all the methods available for safely keeping cows, cattle and other livestock contained, farmers agree that an electric fence is an affordable and effective solution.


An electric fence charger provides a single pulse of electrical current per second when your livestock encounter the fence wire. The electrical shock provided by the charger is harmless yet effective and serves as a psychological message to your cows that reminds them to stay clear of the fence.

Factors to consider in an electric fence charger

The first consideration when selecting a fence charger should be the source of power that will be used to energize the unit. There are three basic choices:

  • Plug-in – The most consistent, effective and cost-effective power source is an 110V plug-in outlet. If the fenced area is close enough to access an electrical outlet, you will want to consider a plug-in fence charger.
  • Battery-operated – If the fenced area is away from easy access to an electric source, but close enough for frequent monitoring, battery-operated fence chargers offer a viable solution. Keep in mind that battery-operated fence chargers require frequent battery changes, in some cases on a weekly basis. It is recommended that when using a battery-operated fence charger, you have at least one backup, rechargeable 12V battery to ensure consistent electrical current throughout the length of the fence. When using a battery-operated fence charger, you will also need to check the power levels more frequently than with a plug-in model. Battery-operated fence chargers will effectively provide an electrical current for fenced areas up to 200 acres.
  • Solar-powered – These models offer consistent electrical power without the continual maintenance of a battery-operated fence charger, making solar-powered fence chargers an effective solution for remote fenced areas. Place the solar-powered fence charger on a section of the fence that receives four to six hours of sunlight each day and won't be damaged by curious livestock. Solar-powered fence chargers store energy from the sun to provide an electrical current throughout the fenced area, even over a series of cloudy days, without needing an alternate source of power. Although somewhat more expensive than a battery-operated fence charger, the solar-powered fence chargers are more ecologically-friendly and will provide effective electrical current for fenced areas up to 100 acres.

Type of livestock to be contained

Whether you are keeping livestock in or predators out, the size of the horses, cattle or sheep will determine the type of fence charger that will be necessary. The larger the animal and the tougher their hide, the more energy will be required to effectively produce a consistent single pulse of electrical current.

Consider not only the livestock being contained within your ranch or pasture area, but also predators such as feral pigs, rabbits or deer. The height and size of the livestock being contained or deterred also has a bearing when determining the height and number of rows of wire that will be connected to the fence charger.

As a general rule, the larger the animal; the more powerful the fence charger needed. Larger and stronger livestock, like stallions or bulls, with a thicker hide, hooves, foot pads or plush fur, such as a bear, require a stronger shock to be effectively trained to stay away from the wire fence.

Size of the area

When selecting the proper fence charger, the number of acres or miles of wire needs to be taken into consideration.

You will need to consider the size and shape of your farm. A square acre requires less miles of wire than a rectangular area of fencing. Additionally, the fence will contain multiple rows of wire, which can add to the confusion when selecting an electric fence charger that will provide enough power to effectively contain the cows, horses and other livestock.

Using the acreage of the pasture is the most effective number to consider when selecting an electric fence charger.

Since the pasture or acreage being fenced isn't an exact square or rectangle, it is recommended that you select a fence charger powerful enough to effectively provide electrical current to your specific fenced area.

Possibility of expansion

Also consider whether or not your fenced area will expand or change in size and/or location over time. In particular, if you have a remote, fenced pasture that is moved from season to season or may be expanded at a later date to accommodate a growing herd, this should be taken into consideration when selecting a fence charger.

It is unsafe to have more than one fence charger on an electrical fence; therefore, if there is a possibility of your pasture size changing, you may want to opt for a larger model.

Type of wire used

Each type of wiring offers features and benefits better suited to specific circumstances. You can obtain fence wiring in a variety of materials, gauges and lengths depending on your specific fence needs.

Some types of wire are more resistant to the electrical current due to the diameter of the fence wire. For example, you will need a larger fence charger when energizing long distances of Polywire.

Polywire, Polyrope and Polytape wire features a mixture of tinned copper conductors and stainless steel conductors, twisted in a special UV-protected polyethylene weave. The strength of the stainless steel, along with the super conductivity of tinned copper, results in high voltage along the entire length of your fence.

Additionally, the height and size of your cows, cattle and other livestock will also have a determining factor in the wire used, the number of rows of wire contained in your fence, and the fence charger model that is installed.

Soil, weather and sun conditions

The ground conditions of the pasture that is being enclosed with an electric fence will also be a determining factor when selecting the proper fence charger. If the ground conditions are heavily weeded or if piles of snow accumulate during the winter months, this can impact the consistency of the electric current flowing through the fence.

If selecting a solar-powered fence charger, the availability of sun exposure needs to be taken into consideration. During different seasons the pattern of sunlight will shift and could impact the amount of energy stored in the solar-powered fence charger. This will need to be considered when determining where the solar-powered fence charger is placed on the fence line or if a solar-powered fence charger is the right choice of energizer for the circumstance.

Ground conditions: dry soil versus wet soil

The most effective situation for an electric fence charger requires moist, rich earth so that the electric current can easily pass from the charger, through the ground system and to the cow's snout or the hide of a horse. However, ideal ground conditions are not always possible.

Clearing up the mystery

Comparing fence chargers from one brand to another can be a challenge. Packaging labels focus on different elements of the fence charger and can be confusing to decipher. One brand may focus on miles of wire while another will emphasize the acreage. Some brands talk about joules and others refer to volts, amps or watts.

  • Volts, amps and watts
    • Volts are a unit of measure that determines the amount of electric pressure; the higher the number of volts, the more electric pressure. High volts are needed when containing larger animals with tougher hide or fur.
    • An amp measures the amount of electricity as opposed to the force of the electricity as in a volt. A larger number of amps will cause a greater sensation for the cow or cattle when they come in contact with the fence.
    • A watt is the unit of electrical power. In other words, it is the combination of the amount of electricity and the electrical pressure: Amp x Volts = Watt. Typically this term is not used on the packaging of fence chargers.
    • Joules: Output or Stored – Joules is a term frequently used in fence charger descriptions and on the packaging of fence chargers, however, there are two measurements of joules: output and stored.
    • A joule is a unit of energy. Watt x seconds = joules. It refers to the energy level of the fence charger and the amount of electricity felt in the single pulse per second generated when the cow or cattle encounters the fence. The higher the volt and amp, the higher the watt. The higher the watt, the more joules delivered per second on the fence line.
    • The important thing to compare when it comes to joules is whether it is output of joules or stored joules. Stored joule energy is approximately 30 percent less effective than the same number of output joules. When comparing fence charger brands by number of joules, make sure to compare fence chargers by the number of output joules.
  • Important selection tip – When selecting a fence charger to consistently contain your cows, horses and other livestock, remember that too little power is the same as no power on your fence line. Select a fence charger that has output Joules equal to the number of acres enclosed; i.e. 2 Joules for up to 200 acres. 3 Joules for 300 acres.
  • Miles versus acres – Another common area of confusion when comparing fence chargers is the question of miles of fence versus acres of property. 1 square mile = 640 acres.
  • An electric fence will most likely have multiple rows of wire. This means the number of miles of wire will increase by the number of wires on the fence. Unless you are just creating a single wire of electric fence on top of an existing PVC railing fence or wooden fence, your electric fence will contain multiple rows of fencing. For example, if you use one row of wire around a 640-acre pasture, you would require four miles of wire. If you use three rows of wire around the same pasture, you would require 12 miles of wire.  

NOTE:  The measurement of the number of miles around an acre varies based on the shape of the enclosed pasture. If you are unsure how many miles of wire you need, it is safest to purchase an energizer based on the number of acres.

Most farmers and ranchers don't want the added responsibility of monitoring the expanse of their fenced pasture areas every day and trimming back weeds to ensure their electric fence continues working.

Ultra low impedance technology means that your fence charger will continue providing an effective level of electrical shock when your cows or cattle come in contact with the fence, regardless of the weather or ground conditions.

Selecting the best energizer fence charger – Key points to remember

Selecting a fence charger can be confusing. However, if you keep in mind a few basic components, you will be able to choose the best fence charger to effectively and consistently contain your cows and other livestock.

  • Power Source – Determine the power source that will be used to provide the energy necessary to operate your fence charger.
  • Livestock – The size of the animals being contained will determine which model of fence charger will be the most effective to adequately power your electric fence. The larger the cow or cattle the more power is necessary.
  • Area – The size of the area to be enclosed also has a bearing on selecting the appropriate fence charger.
  • Ground Conditions – Selecting the area to enclose with an electric fence is also important. When using a solar-powered fence charger, make sure a portion of the fenced area is exposed to the sun for at least 4 to 6 hours each day on average. Weeds and vegetation growth also impact the ability of your fence charger to effectively contain cows and cattle by providing a pulse of electrical shock. Selecting a fence charger that offers ultra low impedance technology may offer the best solution for areas with heavy weed cover.  end mark

—James Falbo is vice president of engineering at Power Wizard Shock Technology.


Photo courtesy of Power Wizard Shock Technology.