Author Topic: [RANT] Why are domestic Uninterruptible Power Supplies such utter crap?  (Read 3342 times)

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Offline nfmax

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I have been chasing this up with the UPS supplier, and they claim it is working as designed. I raised the question of the peak voltage with the UK-based designers of the router, which has a built-in supply, and they told me that it would not tolerate such a high input voltage.

You guys have it easier in the US, as most small SMPSUs are 'universal input' these days, so 100% over-range from 115V is still within specification.
 

Online james_s

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I don't think that lithium-ion or LiFePO4 cells are a simple drop-in replacement for lead acid. I would not use a lead acid charger with my lithium-ion and LiFeMgPO4 batteries, and I'd have reservations about maintaining them at 100% capacity indefinitely. I don't see how they are initially cheaper than lead acid unless you're buying used cells from, say, Battery Hookup, or ordering cells from China, which currently takes up to three months for delivery to the U.S., and involves substantial shipping charges that make it uneconomic for smaller capacity builds. For those options, you have to assemble the battery yourself, which has additional costs including buying a battery management system (LiFePO4 definitely needs one, and I suspect that the same is true for lithium-ion), an enclosure, bus bars, cable and connectors.

That said, there have been a number of discussions about using LiFePO4 for a UPS on Will Prowse's forum at https://diysolarforum.com. I do think that the battery discussed in posts #5 and #8 above would be cheaper than lead acid over time, assuming that concerns around setting it up as a UPS were addressed. I'd be more comfortable doing it if I had a couple of LiFePO4 batteries and a use, apart from a UPS, that involved draw/discharge. Then I could change out the batteries between the UPS and the use that drew down capacity.

There are LiFePO4 batteries that claim to be drop-in retrofits for lead-acid and have their own onboard BMS. Whether they work as designed is anyone's guess though, personally I'd be a little nervous about retrofitting them into a UPS. Stored energy is dangerous already and I've seen stock UPS's burn up more than once. On that small chance that the UPS fails in a way that sets your house on fire, there's a very good chance your insurance will deny the claim if they determine it was modified with batteries not of the original type. It doesn't matter if the modification had anything to do with causing the fire.

I would certainly like to see more UPS's using LiFePO4 batteries from the factory though. They cost a lot more but they offer far better performance under the sort of abuse that UPS's put on the batteries.
 

Offline redg

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There are LiFePO4 batteries that claim to be drop-in retrofits for lead-acid and have their own onboard BMS. Whether they work as designed is anyone's guess though

The battery discussed in posts #5 and #8 has an onboard battery management system. I'm extremely happy with its performance and relative portability in terms of weight, but for the reasons stated three posts up I have reservations about the idea of trying to use it for UPS purposes. When people say that a LiFePO4 is a drop-in, they're talking about form factor. It doesn't mean that the LiFePO4 battery will behave the same way as a lead acid battery, which it won't.
« Last Edit: May 26, 2021, 11:39:37 pm by redg »
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Online james_s

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The battery discussed in posts #5 and #8 has an onboard battery management system. I'm extremely happy with its performance and relative portability in terms of weight, but for the reasons stated three posts up I have reservations about the idea of trying to use it for UPS purposes. When people say that a LiFePO4 is a drop-in, they're talking about form factor. It doesn't mean that the LiFePO4 battery will behave the same way as a lead acid battery, which it won't.

It's good to know that there are at least some of these that work well. There are lots of them on the market and I suspect the quality of the design and construction varies widely. I have certainly seen some that claim to be plug & play, my friend had one in a motorcycle for a while that was sold as being a direct replacement for the original lead-acid battery. It only lasted a couple years before it failed so apparently it was not quite a direct replacement but it was sold as one none the less. I have a Li-Ion battery for one of my older Roombas that claims to be fine to use on the internal NiMH charger, it does in fact work pretty well but I don't know how badly it abuses the cells and I have seen other similar products that did not hold up very well at all.
 

Offline redg

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The battery discussed in posts #5 and #8 has an onboard battery management system. I'm extremely happy with its performance and relative portability in terms of weight, but for the reasons stated three posts up I have reservations about the idea of trying to use it for UPS purposes. When people say that a LiFePO4 is a drop-in, they're talking about form factor. It doesn't mean that the LiFePO4 battery will behave the same way as a lead acid battery, which it won't.

It's good to know that there are at least some of these that work well. There are lots of them on the market and I suspect the quality of the design and construction varies widely. I have certainly seen some that claim to be plug & play, my friend had one in a motorcycle for a while that was sold as being a direct replacement for the original lead-acid battery. It only lasted a couple years before it failed so apparently it was not quite a direct replacement but it was sold as one none the less. I have a Li-Ion battery for one of my older Roombas that claims to be fine to use on the internal NiMH charger, it does in fact work pretty well but I don't know how badly it abuses the cells and I have seen other similar products that did not hold up very well at all.

I assume that you're talking about a gas-powered, not electric, motorcycle. I have a gas-powered bike myself. I'd love to replace my lead-acid battery with lithium, but I've yet to see a legitimate vendor claim that it has a lithium replacement. Although lithium might be fine for a low-powered 50cc bike, in lead-acid terms lithium batteries are not "starter batteries". They are more like lead-acid "deep-cycle" batteries.

The term "drop-in lead-acid replacement" is a marketing term. Legitimate vendors use it principally to mean form factor. Whether a lithium battery is a drop-in replacement functionally depends on one's use. The term does not describe things like charging behaviour, such as cold weather temperature limitations on LiFePO4 charging that can be important for off-grid use, whether for an RV or a property. There are also a number of criteria, not just weight, on which lithium is both different and superior. One of the attractions of LiFePO4 batteries is that they have much more useable capacity than deep-cycle lead-acid batteries. I have no problem with discharging my LiFeMgPO4 battery to 20% remaining capacity. If I did that with a lead-acid battery, I would expect the battery to have a very short life.

I use lithium chargers for lithium batteries. The only NiMH batteries that I use are Panasonic Eneloops, which have their own charger. I don't know enough about NiMH charging to know how comparable it is. I wouldn't use a lead-acid charger for the LiFeMgPO4 battery pictured in post #5. Forgetting behaviour differences, charging with a lead-acid charger would be much slower. I use a 15A charger with that battery, and could use a 20A charger. I use a Yuasa 1A charger for my lead-acid motorcycle battery.

If you want to see differences in quality of assembly between LiFePO4 batteries, Will Prowse's YouTube channel has lots of tear downs. His tear down of the battery that I have is linked in post #8. Almost all LiFePO4 cells are made by a small number of companies in mainland China, which has substantial lithium deposits. There is a battery manufacturer in Australia that makes its own cells. There's also a Canadian company, with a long history in energy production, that plans to start making LiFePO4 cells and batteries in Nevada, where there's a mine that produces lithium, this summer. As of December 2020, when it purchased Lithium Werks's Valence battery business, it is also the maker of the battery that I have.

« Last Edit: May 27, 2021, 02:49:33 pm by redg »
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Online NiHaoMike

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I have a Li-Ion battery for one of my older Roombas that claims to be fine to use on the internal NiMH charger, it does in fact work pretty well but I don't know how badly it abuses the cells and I have seen other similar products that did not hold up very well at all.
The key is a BMS that handles the balancing as well as stop the charging well before the usual 4.2V/cell, 4-4.1V/cell tends to be a good target.
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Offline redg

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The key is a BMS that handles the balancing as well as stop the charging well before the usual 4.2V/cell, 4-4.1V/cell tends to be a good target.

Yes, balancing charge between battery cells, and preventing overcharge, are basic battery management system functions for lithium batteries. Differences are more subtle, but can be important. If you watch Will Prowse's tear down of my LiFeMgPO4 battery (post #8), you'll see that the battery has temperature sensors. These are for monitoring, but also trigger the BMS to stop charging if the temperature of the battery drops below freezing. There are a lot of LiFePO4 batteries that don't have this function, but it can be extremely important if one has LiFePO4 batteries outdoors, say collecting solar energy, where there are cold winters. One sure way to destroy a LiFePO4 battery is to try to charge it when the battery is below 0°C/32°F.

It might be worth noting that nominal cell voltage varies (4.2V in the quote is for lithium-ion), depending on the type of lithium battery. LiFePO4 has a nominal voltage of 3.2V-3.3V. I use a highly configurable Victron Energy charger with my LiFeMgPO4 battery, which has a capable onboard battery management system. The battery reads 14V (3.5V per cell) immediately post-charge, and settles to 13.6V (3.34V per cell).
« Last Edit: May 27, 2021, 07:18:18 pm by redg »
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Offline I_Saldana

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What I want to know though is why they insist on making them mains.

I would much rather see ( for computers that is ) them either integrated in the PSU or attached to the PSU. Those things have 12V lead batteries. The computer needs 12v 5v and 3.3v .. some voltage regulation, buck conversion and bob's your uncle.
Where electronics are concerned, compared to what's already in a PC psu the additions would be minimal.
 

Offline nfmax

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Well, it depends. Of the things I want to run from my UPS, the ONT is supplied by the network operator, as part of the fibre rental. It has a 13A plugtop wall-wart supply. The router is mine, although I bought it from the ISP. It's power supply is internal, 240V input. I could have ordered it with an internal 12V or 48VDC supply, but I didn't, and it's not retrofittable. The switches have external brick supplies, but being PoE, these give out ~55VDC. The Wifi access point, cameras and phones run off PoE. The home automation controller runs off 24DC, but I have already bought a 240V supply for it. I could have gone for a maintained supply, but none of the ones I know of have a USB output to let the controller know when it is running on battery and/or it's time to shut down - they all seem to be designed for alarm panels. OTOH my alarm panel has a built-in battery-backed supply.

240VAC really is the simplest option. If only I could buy one that Just Works!
 

Online james_s

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What I want to know though is why they insist on making them mains.

I would much rather see ( for computers that is ) them either integrated in the PSU or attached to the PSU. Those things have 12V lead batteries. The computer needs 12v 5v and 3.3v .. some voltage regulation, buck conversion and bob's your uncle.
Where electronics are concerned, compared to what's already in a PC psu the additions would be minimal.

Low voltage UPS units have existed, I remember seeing some that were made to install within the PC back in the 386 era. The big flaw with them was that they could not power the monitor so you had to rely entirely on the software correctly shutting down the PC and hopefully saving your work in the process.

The advantage of using mains voltage is that you can connect anything you want, not just the PC. I have about 6 UPS's in operation and only one of those is powering a PC, along with two external hard drives which require a different voltage than the PC. Another is powering my router, ONT, POE ethernet switch, and security NVR, all of which run from DC but not all the same voltages. One is on my TV, AV receiver, streaming player and the floor lamp in the livingroom, nice so brief outages don't restart everything, another is on my Heathkit "Most Accurate Clock" which can take a few days to set itself from WWV if it loses power, and also a frequently used table lamp, providing emergency lighting if the power goes out. Another is powering a couple of Raspberry Pi boards performing various tasks and another network switch, etc. Running most of this stuff on DC would be possible, but it's a lot more convenient to just use a UPS that produces the standard mains voltage so I can plug in anything I want. The conversion efficiency is high enough that there really isn't a lot to be gained by bypassing it.

For the OP, true-sine UPS's do exist, they are not common on the consumer end but there is at least one prosumer aimed one that offers it. The peak and RMS values will be spot on since it's a real sine wave.
« Last Edit: May 28, 2021, 07:57:19 pm by james_s »
 

Offline thm_w

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Offline David Hess

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Low voltage UPS units have existed, I remember seeing some that were made to install within the PC back in the 386 era. The big flaw with them was that they could not power the monitor so you had to rely entirely on the software correctly shutting down the PC and hopefully saving your work in the process.

The one I remember had a little inverter inside and AC socket on the back to power the monitor.
 

Offline BlackICE

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I just bought one of these Cyberpower UPS from Costco, a 1350 VA / 810 W. Should I return it before it fails? I've seen that type of glue used on other products. I wonder does it always become conductive or does it need the right conditions, for example heat and high humidity. It has two 7ah batteries and sells for $100 USD.

https://www.cyberpowersystems.com/product/ups/battery-backup/cst135xlu/
 

Online james_s

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It will probably work for a few years even if it does have that glue that becomes conductive. If it were me, I'd use it until the battery fails and then open it up and see if it looks like it's worth getting a new battery for it. If it fails prematurely just take it back to Costco at that point, they've always had a great return policy. I was there returning something one time and the person in front of me was returning some expired food. I thought that was completely ridiculous but they accepted it.
 

Offline fordem

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In a nutshell you get what you pay for, and those APC BackUPS are the bottom of APC's product line, built to compete on price with every one else's bottom of the barrel product.  You can opt to pay a little more and get one of their better models, for example a line interactive SmartUPS, or go higher and get their "true online double conversion reverse transfer" SmartUPS RT.

Eaton Powerware also offers three lines of product - 3 series, which are your standby "battery-in-a-box" equivalent to the APC BackUPS; 5 series, which are their "line interactive" product; and the 9 series, which are their "true on-line" units.  The 3, 5 & 9, by the way, are not only the first digit in the model number, they refer to the number of power issues, the unit will protect you from.
 

Online james_s

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Line-interactive is a useless feature if you live somewhere that has relatively stable power. It isn't like a ferroresonant regulator that maintains a constant voltage output, rather it has typically a couple of buck taps and a couple of boost taps and selects them in steps. If your voltage is very high or very low for significant periods it could help, but I have never seen the voltage at my house more than about +2/-3V from 120V nominal at any time I've checked. In that case the only thing line-interactive will do for you is significantly increase standby power consumption. Double conversion is much worse in that regard, unlike line-interactive it provides great stability but I wouldn't want one unless I wasn't paying for my electricity.
 

Offline fordem

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Do you really want to lead off with ferroresonant regulators and then get into a discussion on the efficiency of line interactive and double conversion UPSs?!?  The only good thing I have to say about the Sola ferros is that they make VERY effective space heaters, I remember sitting on them to stay warm.

I was selling Best Power Ferrups back in the '80's, I think Eaton still offers them, but unless you have a stable utility supply they can be quite, dare I say it, unstable, and if you have a stable utility feed, then why do you need the ferro?

Running costs aside, if what you're looking for is stability, then double conversion is the only thing that will provide it, if you can't afford to purchase of operate a double conversion unit, line interactive is your best bet, and if that's still too expensive, then don't gripe when the cheap crap turns out to be, well, just cheap crap.

Learn to distinguish between what you need and what you want, does the average domestic installation need uninterruptible power - what is the cost per minute of the down time when an outage occurs, how long is the average outage - there is where you'll find the justification to invest in uninterruptible power, will a 2 mS glitch in the power cause down time - there is the justification for double conversion.
 

Offline nfmax

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Learn to distinguish between what you need and what you want, does the average domestic installation need uninterruptible power - what is the cost per minute of the down time when an outage occurs, how long is the average outage - there is where you'll find the justification to invest in uninterruptible power, will a 2 mS glitch in the power cause down time - there is the justification for double conversion.

What I need is:
  • Protection for various always-on SMPSU devices, with a total load of between 15W and 100W, against brief outages of a few cycles to a few seconds
  • For a subset of these loads (50W max), autonomy of at least 40 minutes and preferably more than one hour
  • Advance warning of impending shutdown, preferably in some standard way, so RPi's running Linux can be safely shutdown without peril to their SD cards
  • Not to have the house set on fire, nor to risk electrocution
  • Not to have damagingly high voltages, generated by the UPS itself, applied to the 'protected' loads
  • Small size and quiet operation (beeps that can be turned off, if a fan is fitted, it must be quiet & speed-controlled)

What I do not need is:
  • 400W or more of standby power, for a short period
  • Less-than-one-cycle switchover times
  • Protection against abnormally low or high line voltages - the loads can pretty much look after themselves, within limits that are exceeded here only once a decade or so

What I want is:
  • A standby power consumption (with fully charged battery) that is as low as possible, and certainly less than the normal power consumption of the protected loads
  • A user-replaceable battery, preferably hot replaceable
  • Built in battery condition monitoring and/or test

 

Offline madires

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In a nutshell you get what you pay for, and those APC BackUPS are the bottom of APC's product line, built to compete on price with every one else's bottom of the barrel product.  You can opt to pay a little more and get one of their better models, for example a line interactive SmartUPS, or go higher and get their "true online double conversion reverse transfer" SmartUPS RT.

Be careful with SmartUPS'. Some of them are featurewise a BackUPS in disguise. APC has weaken the clear distinction between both product lines about a decade ago which is quite annoying.
 

Offline madires

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  • Advance warning of impending shutdown, preferably in some standard way, so RPi's running Linux can be safely shutdown without peril to their SD cards

Network UPS Tools (https://networkupstools.org/)
 

Offline nfmax

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In a nutshell you get what you pay for, and those APC BackUPS are the bottom of APC's product line, built to compete on price with every one else's bottom of the barrel product.  You can opt to pay a little more and get one of their better models, for example a line interactive SmartUPS, or go higher and get their "true online double conversion reverse transfer" SmartUPS RT.

Be careful with SmartUPS'. Some of them are featurewise a BackUPS in disguise. APC has weaken the clear distinction between both product lines about a decade ago which is quite annoying.

Of the three I have tested so far, the APC BackUPS 700 is actually the best performing. It has a standby power draw of 11W to 12W (better than the Riello NPW800 but not as low as the CyberPower); better voltage regulation over a wider range then the Riello NPW800; and a well-behaved pseudo-sinewave output that does not have excessive peak voltages. If only the output connectors were a bit more trustworthy.

The picture below is with a 60W light bulb load, showing the switch from mains to battery
 

Online james_s

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Do you really want to lead off with ferroresonant regulators and then get into a discussion on the efficiency of line interactive and double conversion UPSs?!?  The only good thing I have to say about the Sola ferros is that they make VERY effective space heaters, I remember sitting on them to stay warm.

It seems you completely missed my point there. I was not arguing the merits of ferro-resonant regulators, all I'm saying is that line-interactive doesn't provide a regulated output as many people may assume, it can *only* provide a few automatically selected buck/boost taps which makes it completely useless to most people. The line-interactive portion also has *nothing* to do with the UPS part, it is only active while the incoming power is still present, if the power glitches or drops out the UPS kicks in, at which point it isn't line-interactive anymore, it's just like any other UPS. I don't really see much value in ferro-resonant regulators either, if the voltage goes out of spec I want the UPS to kick in and switch over to battery, I've never experienced a sustained under or over-voltage condition where I live. 
« Last Edit: June 03, 2021, 05:52:37 pm by james_s »
 

Offline GreyWoolfe

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I have a supply of decommissioned APS SmartUPS 1500s that were purchased in 2004 at the start of the program.  When they were phased out in 2015 I snatched up 6 of them.  3 power everything in my office including my workbench and 3 are spares.  All I have had to do is feed them batteries every few years.  Over 240 were deployed to keep Dell PowerEdge servers up and there were very few failures.  A few of the other techs are also using them.  The techs that are using the crappy HP UPSs that we have now hate them.  They will be off program at the end of the year and I have no desire to grab any of them.  The AGM batteries are 12V 18AH in series with big 40A AMP connectors of which I have a number of spares.  I get about 3 years out of set and as I am using them in my home office for work: one on the desk for the laptop and monitors, one for the network gear and one for the workbench, the company pays for the replacement batteries.  Win win for me.  Close to an hour of runtime which is almost always good enough for power outages and they have automatic voltage regulation.
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Online james_s

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I have one of those SmartUPS 1500's too, it's a nicely built piece of equipment but it draws something like 15-20W just sitting there so I don't use it and have been meaning to sell it. The standby draw is not really a problem if the equipment it powers consumes a few hundred watts, but it's a substantial portion of the total load I have on most of my UPS's. If I could put everything on one unit it would still make sense to use but the stuff I want protected is spread all over the house unfortunately.
 

Offline fordem

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What I need is:
  • Protection for various always-on SMPSU devices, with a total load of between 15W and 100W, against brief outages of a few cycles to a few seconds
  • For a subset of these loads (50W max), autonomy of at least 40 minutes and preferably more than one hour
  • Advance warning of impending shutdown, preferably in some standard way, so RPi's running Linux can be safely shutdown without peril to their SD cards
  • Not to have the house set on fire, nor to risk electrocution
  • Not to have damagingly high voltages, generated by the UPS itself, applied to the 'protected' loads
  • Small size and quiet operation (beeps that can be turned off, if a fan is fitted, it must be quiet & speed-controlled)

What I do not need is:
  • 400W or more of standby power, for a short period
  • Less-than-one-cycle switchover times
  • Protection against abnormally low or high line voltages - the loads can pretty much look after themselves, within limits that are exceeded here only once a decade or so

What I want is:
  • A standby power consumption (with fully charged battery) that is as low as possible, and certainly less than the normal power consumption of the protected loads
  • A user-replaceable battery, preferably hot replaceable
  • Built in battery condition monitoring and/or test

I think we need to revisit the concept of want & need, but before I do that, I want to define what a UPS is designed to do.

The majority of off-the-shelf consumer UPSs are used with compute devices, and the intent is to allow the orderly shut down of the system in the event of a power outage so as to avoid the loss of data, this generally takes no more than fifteen to thirty minutes, so this is what the product is designed to provide.  There are "mission critical" systems where downtime is not acceptable, and use cases where the cost of the downtime can be enumerated in hundreds or even thousands of dollars in lost revenue, and for these type of installations, standby power is what is required, and the UPS is needed to bridge the gap between the loss of the utility power and the standby power coming online.

As mentioned in an earlier post, off-the-shelf consumer UPSs are built to compete on price and most UPS manufacturers & engineers will advise against running their product for the sort of time frame listed in "Need #2", it's not that they don't have a product or they can't build a product that can deliver the requirement, but rather the use case is not the norm, so it requires a specialized product or configuration - extended run times can be achieved by specifying a unit that allows full time operation of the inverters (so double conversion), equipping the unit with additional battery capacity, and a suitable charger - it also needs to be made clear to the customer that the batteries will need periodic replacement, and frequent deep discharge of the batteries will necessitate more frequent battery replacement.  These "extended run" systems are going to cost considerably more than a conventional off the shelf product, not only to purchase, but also to operate and maintain, which is the primary reason that the professionals will advise against them.

Back to need & want - I see much of your list as "nice to have", which is more of a want than a need - what will it cost you if the entire load goes down for more than a few seconds (Need #1)?  what will it cost you per minute if the "subset of the load" goes down for over forty minutes (Need #2)?  For Need #3, I can't think of a commercial product that doesn't come with some sort of AC failure and/or low battery signaling right out of the box, getting it to work with a RaspberryPi is slightly more challenging (again not the normal usage case), but not impossible (let me know if you want details, I have done it)

I can understand that you don't want the house to catch fire (Need #4), but that's easily resolved, don't install whatever it is in the house, install it in a data center with a fire suppression system - I'm going to stop here rather than go through your list item by item, because I'm sure you have recognized that I distinguish the difference between need & want based on a monetary value - you can get almost everything you've listed, provided you're willing to pay for it, which, based on "Want #1", I'd say you're not.

Bottom line - if you're running a business, you build a use case based on loss of revenue to explain to management why you need a UPS, if it's a hobby, then it's no longer a need, it's just "nice to have".
 


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