infrastructure

Backup Power: 9kW-ish Portable Invertors

Just a few days before Christmas 2021 we bought a Predator 9500 portable invertor generator. Back then, it was one of the first of a new generation of inverters delivering 7,500 watts continuous power, with 9,500 watts peak.

The Predator brand is sold by Harbor Freight. The 9500 model was introduced in 2020 at $1899. Demand was strong, and they were in short supply for a long while. By the time supply was improved the list price had gone up to $2399. It has since gone to $2499, but you can still get them for less during special promotions. We managed to get ours using a last-minute pre-Christmas coupon good for a discount of 25%!

Over time, similar models have emerged from several other companies like Genmax and DuroMax. It’s quite apparent that these are all made by the same manufacturer. They vary only a little in specific features and the color of the plastics.

Three Inverter Generators

Not long ago, Gavin’s Garage offered an unboxing video of the Pulsar PGD95BISCO Super Quite Dual Fuel 9500W Home Use Backup Portable Inverter Generator.

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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.

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Flume: Know About The Flow

As I’ve mentioned previously, household instrumentation is addictive. Further, it can draw out my compulsive tendencies. I’ve been wanting to add a smart water flow meter to our home for a while. This was motivated by the fact that we have gardens, and we occasionally forget the water is on. On such occasions the result is a soggy, boggy part of the yard and an unwelcome spike in the water bill.

A False Start

Last year, I tried an initial experiment using the Orbit B-Hyve Smart Hose Faucet timer. This device would only control one faucet, but under $60, it was cheap. I thought it a good experiment. The trouble is I could not get it to work for me. I was never able to get its little hub to connect to the device.

As a result, I returned it and began to investigate devices that would meter flow in the main water line from the city. I hoped that I could set an alert to tell me if we left the water running too long or into the evening. It would not turn off the water, just alert me that I had to do it.

Red Pill or Blue Pill?

I considered two kinds of add-on flow meters designed for DIY installation by the homeowner. One type, as embodied in the Stream Labs Smart Home Water Monitor, clamps onto the water supply line and read the flow using an ultrasonic beam sent through the pipe. They work with copper or plastic pipe. At our home the main water supply line from the city is plastic, so this could work for us.

Flume-Box-and-Devices-copy

However, I settled on the simpler approach used by the Flume water flow meter. It has a sensor device that clamps onto the city water meter. This senses the motion of a magnet on the rotating mechanism inside the city meter.

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Decisions: 2021 Household Projects

As we come to the end of the year, I’m looking back across a range of substantial household projects. We rather famously lost power for a few days back in February 2021 during an unusually cold snap. This lead to some additional thinking about household projects, including the new air conditioner. Specifically, how best to adapt our home to operation without utility power? After all, the Great Texas Freeze of 2021 was not the first time we lost power for days. We were without power for several weeks after Hurricane Ike in 2008.

Generac Standby Generator Beauty Shot copy

The most common approach that we see around the neighborhood is the installation of a standby generator. These are permanently installed systems that startup and take over when utility power fails. Generac, Kohler and Cummins are the most common brands. They typically run on natural gas and I’ve seen systems from 14 kW to 32 kW hereabouts.

Standby Generator vs Air Conditioner

Given the position of our home on the lot, and the location of the gas meter and breaker panel, it’s not really practical for us to install a standby generator. It would be prohibitively expensive given the required location of the generator. We’d need to run buried pipe for natural gas, and conduit for electrical cable, a considerable distance. The cost of the installation is much more than the generator itself. The entire project cost is as much as a new air conditioner, for a benefit that that would only occasionally be realized.

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New Gear: Eaton 9130 Dual Conversion UPS

We have a pair of UPSs here; one in the office and another in the house. In both cases, they run the network core; Ethernet switches, Wi-Fi access points, IoT hubs and the like. Our reliance on power-over-ethernet means that there are actually quite a lot of gear that’s on the UPSs.

For many years the UPS in my office was made by Belkin. It was cheap. It did the job, sustaining the network core through many a minor outage. Being fanless, it was silent…which I deeply admire.Eaton 9130 2UHowever, as with most low-cost UPSs, it was “line-interactive” design. In such a design the power provided by the batteries and invertor is connected in parallel to the utility power. When utility power falters the local circuitry tries to make up the slack. The design is simple. Any UPS under $500 new is almost certainly a line-interactive design.

More sensitive gear is better served using a more sophisticated design known as “online” or “dual-conversion.” An online UPS puts its active circuitry between the utility power and the load. The utility power is turned into DC, which feeds the batteries and the invertor, which makes brand new, pristine, stable AC power for the load.

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Amazon Sidewalk Approaches

As a household that has several Amazon Echo devices, I feel obligated to share the news about Amazon Sidewalk, including how to disable it.

What is Sidewalk?

Sidewalk is a “feature” in the latest firmware for the current generation of Amazon smart home products, including; Echo smart speakers, Ring doorbells & security cameras, and Tile trackers. When enabled, Sidewalk capable devices used by neighbors, visitors or passers-by are able to leverage your local internet connectivity.

Amazon says that these Sidewalk interlopers are allowed a limited amount of bandwidth, just 80 kbps, which is about the same as a tradition VoIP phone call.

Why Sidewalk?

That’s simple – ubiquitous connectivity is very convenient. Amazon knows this from years of experience. For example, their WhisperNet was a mechanism leveraging AT&T’s 3G mobile network to provide ubiquitous connectivity to early Kindle e-book readers.

Tile tracker

Imagine someone who uses Tile Pro to track their car keys. They are, as so many do each day, dropping their child off at Travis Elementary School, which is across the street.

It could be very handy if their Tile Pro found our front room Echo Dot, allowed it to ping Amazon servers. If they later lost their car keys, Amazon would know they had been near our home. Presumably, Amazon would have a more detailed record of their location that might otherwise be possible.

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