UPSes compared to guard dogs

Somebody using the handle JeffyPoooh (yes, ‘ooo’) left a comment on The Register that is an only slightly exaggerated summary of the reasons for UPSide:

You’re concerned about your family’s safety. So you get a guard dog. The dog costs a fortune. It immediately poops on the floor. Then it chews off the entire left side of your Bang and Olufson. It bites the postman’s fingers. It then sleeps through an actual burglary. And finally it eats one of your children.

This is the UPS experience: If they’re not preoccupied with smoldering their lead acid batteries, then they’re busy buzzing and arcing. Then they blow an internal fuse on the output, and your Great American Novel is suddenly lost, again, for the third time. Then there’s an actually power failure (Yay!), so they turn on their patented 387 volt offset square wave, and your PC is instantly corrupted. Meanwhile battery acid squirts out onto the ceiling, again. Then, while you’re out trying to buy a replacement PC, the UPS catches fire and burns your house down.

I’d happily pay $800 to not have one.


  1. I’m just enjoying the comments to the effect of “building a UPS is incredibly hard, and it’s just not possible for several technically-skilled people to ever build one, because!”

    Yeah, it’s a miracle that one was ever built in the first place. Probably nuclear fission involved, or maybe nerve agents.

  2. A bomb that only goes off when least expected. Sign me up.
    I expect periodic updates. Like calling the fire department when activated.

    1. I’ve never had a problem with any of my UPS at home. Everything important is covered by one. One large cap in a large UPS at the HF Receiver Site at Clark went “boom” and blew panels off and made a big mess of the rest. Then one at later civilian work that had had maintenance and known issue fix deferred because the upper management thought we couldn’t afford the downtime. Until it went boom. Then two weeks later, the repaired system went boom. Then we got a brand new UPS. No booms yet.

    1. As long as there’s surge protection… it’s hard to see how it’s much different!

  3. You’d spend $800 to have something *REAL* that does it’s damned job for real and does it right.

    You’ve already talked about a Maker type thing. It’s still doable. But you need to deal with Lithium Iron Phosphate type chemistry and/or ultracapacitors combined with an Arduino or something like a NanoPI Neo or Raspberry PI ZeroW type controller with an OLED/E-Paper display.

    It won’t be cheap, but that’s the point

    1. Then the bearings seize and, at best, you have a juggernaut energized with several kWh following an unplanned trajectory through your house. At worst, the flywheel disintegrates and you have multiple pieces of shrapnel energized with several kWh following unplanned trajectories through your house.


      I don’t think there’s any completely safe way of storing energy in this kind of quantity.

  4. Chemical storage is as safe as it will get. Consider using gravitational potential energy….
    1 KwH = 3.6 MJ. With g at 9.81 m/sec2 and assuming a 10m lift that requires a 36,710kg weight.

    Or, 80,000 lbs lifted 33 ft in the air. Per KwH.

  5. For reference:
    Hydrogen at 700Bar: 142 MJ/kg
    Diesel fuel: 48 MJ/kg
    Propane: 46.4 MJ/kg
    Gasoline: 44.4 MJ/kg

    1. I don’t know what it takes to safely contain H2 at that pressure, but one nice thing about using a pressurized fuel is that you don’t need a fuel pump. For home use, I’m thinking “bury it below the frost line” is a good first cut at “safely contain”.

      1. The thought of a pressure vessel below grade gives me the heebie-jeebies! How do you inspect it or protect from corrosion? I also expect it would be forbidden by safety codes, as all the propane tanks I see are free-standing.

        With a liquid fuel you can use a gravity day tank to get fuel to the generator if that is your concern..

        700bar is ~10,000 psi so big, heavy, gas bottles.

        1. Propane tanks are typically in the 100-200 psi range, and even at that, codes require them to be 5/10/25 feet (up to 125 gal /125-500 /over 500) feet from any buildings. And the codes do allow them to be underground, but they require special coatings to prevent corrosion.

          That you only see above-ground tanks is partially a function of the fact that the buried ones aren’t where you can see them.

          For 10 Kpsi I think I might consider excavating a larger hole, setting up concrete forms and pouring floor and walls as if for a basement, complete with sump pump to remove any water that finds its way inside, so that in the event of an explosion the ground is still helping hold the concrete in place.

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