Hughes Autoformer (Does it Steal Power?)

2022-02-06
Chad

This article (and video) are my opinion, based on a good understanding of electricity (from my military training) as well as several conversations with experts. While I wish I had the equipment to fully test these theories, I do not. However, Mike Sokol (RVElectricity.com) IS doing an extensive study on this very device and its effect on RV Park power. This study is ongoing, but I will post a link here, with a summary, when he is finished.

What Does it Do?

The Hughes Autoformer is a step-up transformer. It steps up the voltage by 10% (when below 113V) to protect your RV.

The Controversy

When we first discovered the Hughes Autoformer a few years ago, initial research turned up some controversy! The rumor was that the device “steals” power from your RV park neighbors and that it might soon be banned by RV parks!

After our time in Las Vegas where we had very low voltage, it was time to revisit this! This thing could have REALLY helped in that situation! The low voltage, in combination with the extreme heat, has us jumping through hoops to keep our ACs running. If we had the Hughes Autoformer, most of our issues would have been eliminated!

Watt's Law

Before we jump into the meat of the topic, you need to know Watt's Law:

Watts = Amps x Volts

It's the factor of Amps and Volts that do Work (Watts). Our friends at Battle Born have a great article if you want to dive a little deeper.

It's also important to know a little bit about the different types of loads, primarily inductive and resistive.

Inductive Loads

Inductive loads are ones with coils of wire that convert current into a magnetic field, like an electric motor. In an RV, this is your AC fan and compressor. Your AC units are typically some of the most power-hungry appliances in your RV.

With an inductive load, if the voltage drops, current (amperage) will increase to make up the difference in the Watts = Amps x Volts equation to maintain the workload.

Resistive Loads

Resistive loads are ones that generate heat to do work. An electric water heater is a perfect example.

With a resistive load, if the voltage drops, the current does NOT increase which means overall power (watts) also decreases. However, that load will typically have to run longer to accomplish the work. The heating element in your water heater will not get as hot, meaning it will have to run longer to get the water to temperature.

Stealing Power?

The core of the argument made against the Hughes Autoformer is that it will increase the amp draw from the pedestal to step up the voltage on the RV side. This is absolutely true! But, that's not the whole story.

For a basic example, we're going to use an inductive load of 6000W in the RV. While, in reality, this will likely be a mix of inductive and resistive loads, it is my assertion that the majority of the load will be inductive. Consider running three 1500W AC units (very common in the summer) is 4500 of the 6000 watts and that's all inductive.

That 6000 Watts at 120 Volts AC will draw 50 Amps (6000 / 120 = 50). Now, drop the voltage to 105.

That 6000 Watts at 105 Volts AC will draw 57 Amps (6000 / 105 = 57).

You're ALREADY drawing an extra 7 Amps from the pedestal. Everyone in the RV park on that circuit with 105 Volts is drawing more amperage.

Now, plug in the Autoformer and run up that same 6000W load.

On the RV side of the Autoformer, the voltage is now 115.5V (10% boost) and the amperage on that side is 52 Amps. On the pedestal side, it's still drawing 57 Amps. Nothing has changed for the RV Park and your neighbors. The Autoformer has simply isolated the RV from the potentially damaging amperage.

Yes, in reality, some of the load will be resistive like our water heater example. For those loads, the Autoformer will absolutely draw a higher amperage than your neighbor's identical water heater. BUT, your neighbor's water heater will have to run LONGER to heat up the same amount of water. So, in the end, you're using the same (at least very close to the same) amount of power as your neighbor to heat your water.

Maximum Power

Another argument for using the Autoformer is, you can never pull more Amperage than the pedestal can provide, period. A 50 Amp RV pedestal is actually TWO 50 Amp breakers. If you try to use more than 50Amps on either line (RVs have two 50A lines), the breaker will blow. You simply can not use more than 50A on either line!

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