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How-To Geek: Be Careful Before Running Your Computer From a Gas Generator

The web site How-To Geek has long been a useful resource. Last week they published an article entitled, “Be Careful Before Running Your Computer From a Gas Generator.” Given our experience during the Great Texas Freeze of 2021 this hits close to home. It’s a reasonable article overall, but it has a couple of holes that I’d like to fill.

How-ToGeek on Lenovo X-1-Carbon

Mr. Butler is absolutely correct, a traditional generator can be a problem when running sensitive electronics like computers or TVs. We discovered this in February 2021 when our reasonably new furnace would not run reliably on the generator. I would not have guessed that a gas-fired furnace would present a problem. However, the electronically controlled, variable speed blower struggled to start when connected to the dirty and lumpy generator power.

He suggests using a UPS to protect your sensitive devices from the generator. That’s a nice idea, but there is some subtlety to that as well. The type of UPS matters.

Uninterruptible Power Supplies (UPS)

Our older, admittedly inexpensive, line-interactive UPSs absolutely freaked out when connected to generator power. They saw the variability in the generator output as something to be corrected, but way beyond their scope. They reacted very badly, cyclically putting backup power in/out of circuit every couple of seconds.

This was totally unworkable for any attached loads. As a result, I had to take both UPSs offline. That meant the associated loads were connected to the generator by way of a simple surge-protected outlet strip. That’s not a lot of protection.

In the year since then we have migrated to using online (aka Dual Conversion) UPSs. These fully buffer the load from the incoming power. They have no issue with running from a generator.

Here’s a brief overview of Line Interactive vs Online UPS.


Mr. Butler correctly describes the manner in which a traditional generator (pictured below left) creates electricity. The process of generating the AC power is largely mechanical. The engine runs at a constant 3600 RPM in order to ensure the alternator is creating power at 60 Hz.

As the electrical load varies it will require more/less torque from the engine to keep the alternator rotating at the correct speed. You can hear the engine sound change in reaction to an increased load. For example, when you turn on a significant appliance. The resulting AC waveform can have significant noise and distortion. This can vary as the generator reacts to changes in load.

Further, since the engine must always sustain 3600 RPM to deliver 60Hz power, it burns a relatively constant amount of fuel-per-hour, regardless of the electrical load.

Predator Generator & Inverter


What Mr. Butler does not explicitly mention are invertors like our Predator 9500 (pictured above right.) Invertors use a more sophisticated process to generate power. In an invertor, the raw AC electricity created by the alternator is rectified into continuous Direct Current (DC) power. That DC is then passed into an circuit that creates brand new, pure sine wave power. The AC waveform produced by an invertor is at a constant voltage and extremely clean. Free of distortion or other defect.

YouTuber Jason Wallace has a nice video comparing utility power to an invertor and a traditional generator.


Also, in an invertor the engine does not need to run at a constant speed. It only needs to run hard enough to deliver the power required by the current load. Most have variable, load reactive throttles, and will automatically throttle up or down as necessary to respond to demand of the moment.


In our Predator 9500 this is called the ESC Throttle (upper left in the picture above.) When this is off the engine runs full-out constantly. With it turned on, the engine speed varies in response to the load. The result better fuel economy, while always delivering pure, clean power.

Historically, inverters were smaller than portable generators. It’s not uncommon to see RVs carrying a compact 2-4 Kw invertor to run the lights and air conditioner. More recently, models in the 6-8 Kw range have been offered by a number of companies.

Considering Loads

Not so long ago a desktop computer would have been the most sensitive load attached to our UPS or generator. However, traditional desktops have fallen out of fashion. More and more people are using laptops. Laptop power supplies are less susceptible to the irregularities of generator power. Also, the laptop battery negates the requirement for a UPS.

Then again, there are more and more electronics in our homes. Sometimes in places you might not our furnace. While invertors are more costly than a traditional generator, there’s more-and-more reason to prefer the cleaner AC power they provide.

Portable Power Stations

Jackery 1000The How-To Geek article mentions portable power stations as one possible solution. While I don’t disagree, these large rechargeable battery packs still feel like a niche item.

I appreciate the fact that they’re silent and have no moving parts. They seem great for camping, where the need for power is limited. Or powering a specific critical device…like a CPAP machine.

However, they don’t have the sheer capacity to address many situations. And they are still very costly on a per kW/h basis.


As with most technical matters, the devil is in the details. And there can be quite a few details to be considered. We’re very happy with the strategy that we’ve put in place to see us through loss of utility power. We’ll not be cold, overheated, or otherwise left in the dark.

Hopefully by sharing our experience and lessons learned we can help others with their strategy for keeping the lights (and everything else) on when the power goes out.

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