The energizer on your electric fencing system will work 24 hours a day, seven days a week. So it's important to choose one that's well-suited to your operation.

“Recommendations vary depending on what type of animal a producer is trying to confine,” says Jay Solomon, University of Illinois-Peoria extension ag engineer. “His needs are different if he's keeping in a few show animals vs. a large herd of stockers.”

“Unfortunately, there's no standard in the industry that says you need a certain type of charger to cover so many acres,” explains Buddy Rowlett. He's a territory manager in Tennessee and Kentucky for Gallagher Livestock Management Systems.

“In addition to the type of animals you have, your decision needs to be based on how clean and well-maintained you keep your fences and what type of fencing products you're using,” says Rowlett.

The power capacity of chargers can be rated in several ways, including miles or acres of fence powered, voltage, joules and ohms.

For best results, both men recommend buying a low-impedance energizer with high voltage and a short pulse duration. A charger should be able to maintain guard voltage — the minimum voltage needed to keep animals in the fenced area — at all times.

They recommend a minimum of 2,000 volts for beef or dairy cattle and 5,000 volts for sheep.

“The more wool or hair the animal has, the higher number of volts you need,” says Rowlett, who prefers a charger that puts out at least 7,000 volts. “If something touches the fence, whether it's weeds or a tree limb, you've still got plenty of voltage left to overcome that short.”

A short pulse duration is needed to give animals an effective shock and then enough time to get away before it hits them again.

“A good charger will be on for 0.0003 second and off for a full second,” says Rowlett.

Another way to compare chargers is to look at joules. “Joule ratings are the best way to compare chargers among different brands,” says Solomon.

These ratings take into account the volts, amps and pulse duration. One joule is equal to an output of one watt/second.

“Chargers rated at less than one joule are useful for fencing in small acreages,” says Solomon. “A properly installed eight- to 15-joule energizer will work effectively for most moderate-size operations. As the length of energized fence increases, more energy (joules) will be required to maintain the minimum guard voltage.”

Another consideration is the voltage at a given level of resistance, which is measured in ohms.

“An ohm reading of 4,000 to 5,000 represents a light weed load and average operating conditions,” says Solomon. “Test results reported at 500 ohms represent heavy weed pressure.”

If your charger isn't performing as well as you think it should, make sure you have it grounded properly.

“The grounding is the most important thing,” says Rowlett. “Our company recommendation is three 6' ground rods for each charger.”

“The ground rods should be spaced a minimum of 10' apart,” Solomon adds.

Final points to consider: Buy your equipment from a knowledgeable, reputable supplier who can help with breakdowns and offer assistance. Then monitor your fences regularly with a digital voltmeter, to make sure the charger is working.