Author Topic: [RANT] Why are domestic Uninterruptible Power Supplies such utter crap?  (Read 3354 times)

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Offline nfmax

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I'm trying to find a UPS to keep my network equipment running during power outages - 50W to 100W total load. I have an APC BackUPS 700 which I use for the PC. It's my second. The first had such dodgy output connectors that a careless touch against the output cable caused a power interruption to the load. The second was better at first, but is now developing the same problem. Further, I see they have changed the design to use a non-standard USB cable connector, for which they do not include a cable. And they are out of stock (permanently). And the thing takes enough power just sitting there doing nothing to keep it uncomfortably hot - about 15W.

I tried a CyberPower 'brick' type off Amazon. At least this one had a more respectable idling power consumption of 2 to 3W, once the battery was charged. I tested it using a 60W bulb load, which it managed to keep going for nearly 50 minutes, but the peak to peak output voltage was uncomfortably high to start with - 724V. That's equivalent to 256V RMS, more than the legal maximum here of 253V. It also got pretty hot while running. The killer feature was that it kept on getting even hotter while it recharged the battery, eventually setting off my smoke detector at 1am! Not actual smoke, just hot plastic.

That went back for a refund. Maybe it was a faulty unit, maybe a nasty cheap Chinese design.

Then I tried a local specialist supplier, and they recommended me a Riello NetPower NPW800. This one also takes 15W or so idling and gets uncomfortably hot while operating. Its real killer feature is that after 12 minutes or so of battery operation, a (tap-changing?) relay clicks, and the peak to peak output voltage goes up to 792V, equivalent to 280V RMS, and stays above the equivalent of 253V RMS for no less than 20 minutes!! I thought these things were supposed to protect against mains over-voltages, not generate them!

I used to have a trusty old Liebert doing the same job, but that finally died after 20 years service (several battery replacements, of course). We seem to be stuck with nasty knock-off copies of this same 30 year old design, cost engineered down to the point where they basically don't work. It's either that or spend thousands on a server rack grade UPS system, grossly over-specced for the job, and wasting even more power.
« Last Edit: May 21, 2021, 07:54:35 pm by nfmax »
 

Offline thm_w

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How often are you plugging and unplugging stuff from the APC? Can you open it up and bend the pins back a bit?
I'm guessing most of the 15W is float charging of the lead acid battery, although they say 7W charging.

For the USB cable, if you have a RJ45 crimper you can make one yourself. About the same price to buy a crimper kit than buying that cable (~$25), many places selling the cable though.

It is crazy though that these type of devices can get away with not specifying idle current at all in their datasheet. Let alone meeting some sort of minimum standby power requirements.
Same deal with some power bars, etc.

Replacing the lead acid with LIFEPO4 would not be cheap but would end up in a superior UPS.
 

Offline nfmax

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How often are you plugging and unplugging stuff from the APC? Can you open it up and bend the pins back a bit?

I never unplug anything from the APC, just accidentally touching the power cables when plugging RJ45's into the switch sat next to it.
 

Offline DrG

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I have used a CyberPower CP1200AVR https://www.cyberpowersystems.com/product/ups/avr/cp1200avr/ for the last eight years and have never unplugged it from the mains. Less than US$150. I have a desktop and a monitor plugged into it at all times. It has never caused me problems and has saved my butt many times. It has been particularly good at brief outages (flickers) I always hear the click on and computing goes on without any interruption - other devices that are not on the UPS do not fare as well and reboot/reset. When there is an longer term outage and I am here, I complete what I am doing and save the work and shut down. I don't know how long it would last, but it definitely makes it for long enough to do what I need to do.

Not sure if that helps, but I am happy with this one and, frankly, did not think it would last this long. If it fails tonight, I will buy another one tomorrow.
« Last Edit: May 22, 2021, 01:49:42 am by DrG »
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Offline redg

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Replacing the lead acid with LIFEPO4 would not be cheap but would end up in a superior UPS.

There are several threads about doing this on Will Prowse's DIY Solar Forum: https://diysolarforum.com

The forum covers LiFePO4 batteries independently of solar, and the threads come up with a search for UPS in the title.

It is more expensive and more complicated than using AGM batteries, but there's a decent argument that it makes financial sense over time. If you can anticipate outages, or "uninterrupted" isn't important, something like a Jackery may be the way to go, especially if you have other uses for portable power.

I recently set up a LiFeMgPO4 battery (Lithium Werks Valence, photo below) and 300W (600W peak) inverter. It's an excellent, reasonably light portable power source, but I haven't tried to make it work as a UPS.


« Last Edit: May 22, 2021, 11:34:10 am by redg »
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Offline james_s

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While I won't say the consumer UPS units are amazing quality, I still have not had the problems you're having. I have about half a dozen UPS units in my house, a mix of APC and Tripp-Lite and they all do the job. I looked for ones that are Energy Star certified and the standby consumption once the battery is charged is only 2-3W. The Tripp-Lite units are particularly nice in that they use an inverter topology that doesn't rely on an iron transformer and at light load they are significantly more efficient than the APC units I have although the downside is that you have to unscrew and open the whole housing to replace the battery. I have never seen unusually high voltages out of any UPS, mine all tend to produce around 110-115V relative to the 120V nominal line. They are "modified sine wave" which is really just a square wave with dead time so the peak and RMS values match those of a sine wave.
 
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Offline ChuckDarwin

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@redg,
Cut off leads in the centre of the battery-dual lead system?
 

Offline redg

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@redg,
Cut off leads in the centre of the battery-dual lead system?

Those ports are for data cables used to connect these batteries in series, which I'm not planning on doing.

The battery is part of this series of batteries:



Will Prowse did a teardown about a year ago. I did not pay $1250 :) It was excess inventory, full capacity, and I paid just under $200.

« Last Edit: May 26, 2021, 09:52:20 am by redg »
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Offline nightfire

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In short: you get what you pay for. Those small units that can be sold for 100-200 $$$ or €€€ usually consist of a small voltage input detector and some switching relay to keep costs down.

If you want real quality, that also is able to filter out the usual garbage from the net input, you have to go double-conversion or at least some high-quality line-interactive UPS with netfilters...
And those are way more expensive, but the overall quality is a different league.

At work in our small server room I have 4 2kVA units as an a/b system setup, and including remote management cards I am quite happy with them- but those were around 1000 €/piece...
 

Offline todd_fuller

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I went down a similar path about a year ago. I went through a series of consumer UPSs over time. Moving up each time thinking they were going to perform better. 

 I ended up buying a Liebert GXT4 1500VA UPS. Double-conversion, hot-swap batteries, network management, load shedding, etc, etc. You can get them for less than $300 w/ fresh batteries. If you decide you need more runtime, many of these enterprise units have capability to add additional battery packs.

For anyone considering this path, carefully look at the kind of plug the unit needs. Pretty much >1500VA is going to have a plug most of us don't have in our homes (in US). Also, before you jump into the online or double-conversion models, consider the noise level of the fan since they run the inverter 100% of the time and it needs cooled. 

 

Offline james_s

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I don't think most people would want one of those in their home, I certainly wouldn't, simply because of the poor efficiency. I'd be surprised if they manage better than 80% on a good day, which means you're throwing away a significant percentage of the power flowing through it as heat. I tested a bunch of different UPS's I scrounged and rejected anything that consumed more than 3W idle with the battery charged. It adds up over time, especially when you have several of them spread out in different places.
 

Online bob91343

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APC has always been on my don't buy list.  Their advertising is worse than objectionable, or at least used to be.

Tripplite is famous (with me) for marginal design.  Very cheaply made.

So what does that leave?  I would lean toward DIY if you have the time, patience, and competence.
 

Offline james_s

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All of the 6 or so UPS units I have in service currently are either APC or Tripp Lite, they've all worked flawlessly, a few of them are more than 10 years old. I don't understand what the issue is? I've been inside them and they're built like any other consumer electronics, not spectacular but perfectly adequate. I had a couple of Eaton units that were nice too but I gave them away because their standby draw was almost 5W, around double that of the APCs.
 

Offline nfmax

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All of the 6 or so UPS units I have in service currently are either APC or Tripp Lite, they've all worked flawlessly, a few of them are more than 10 years old. I don't understand what the issue is? I've been inside them and they're built like any other consumer electronics, not spectacular but perfectly adequate. I had a couple of Eaton units that were nice too but I gave them away because their standby draw was almost 5W, around double that of the APCs.
The one UPS I have tried with a standby consumption less than 15W proceeded to wake me up in the middle of the night by setting off the smoke detector. The second unit applies an excessively high peak-to-peak voltage* to the units it is supposed to be 'protecting', and takes about 18W idling with a fully charged battery.

(*) The RMS voltage is within specification, but we are all EE's here, aren't we?
 

Offline SeanB

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Try to find a tossed out rack mount UPS, which will very likely just need new batteries, but is tossed out because the typical rack user will only buy OEM, which works out at being around the price of a new one. Got 2 of them for free from a local IT company, just ask them if they have some around, you will get typically IEC connectors on the input and output, though some have high current versions, so you will need to buy the rewireable cable sockets to use them. Using an APC 750XL at the moment, with the batteries external to it, as the ones it came with were stone dead, and I wanted more run time, so 2 60Ah car batteries are now plugged into the external battery socket.

The 2 rack mount units, one Eaton and one APC, probably work perfectly, just that I have never put new batteries in them, as they need 36 or 48V to operate, and I did not have the spare SLA batteries around to test them, the internal cells were well cooked. Heavy units, even without the batteries, so would probably work well and give you more than you need.

With your networking equipment it likely will run fine off 12VDC, so a simple UPS would be to have a regulated battery charger and a 12V battery, and connect the equipment to this instead. Easiest way to do this is to look for a security system power supply, which has a power supply that charges a SLA cell, and also provides operating current for the cameras and DVR from the battery. Lowest losses, though the charger/power supply will lose around 5w in operation providing the regular load.
 

Offline james_s

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The one UPS I have tried with a standby consumption less than 15W proceeded to wake me up in the middle of the night by setting off the smoke detector. The second unit applies an excessively high peak-to-peak voltage* to the units it is supposed to be 'protecting', and takes about 18W idling with a fully charged battery.

(*) The RMS voltage is within specification, but we are all EE's here, aren't we?

Well none of mine have that problem. They don't run hot at all, and how could they when drawing only 2.5W? None of mine produce an excessively high peak to peak voltage either, I've looked at them all on a scope, and all of mine produce a square wave with dead time so the peak to peak voltage is lower than that which comes out of the wall. The RMS is a tad low on mine too, 110-115V rather than 120V but it's adequate for keeping the equipment powered. I just have not seen any of these issues that people are complaining about here, it sounds like a defective device or a particular model that has issues, not an entire brand or class of devices. At the last place I worked where we had desktop PCs we had dozens of APC UPS's and I don't recall ever having any problems with any of those except for faulty batteries when they got older.
 

Offline nfmax

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I have emailed details of my test measurements to the local supplier, and they phoned me back. They are escalating the case to Riello - it may be a faulty unit. It still takes too much power when in idle mode, though that could be part of the fault too.

Look at the waveform - the 'on' time each cycle is much too narrow.
 

Online oPossum

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Vrms of 235 indicates that the pulse width is close to what is should be for a "modified sine" inverter.
 

Offline nfmax

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Vrms of 235 indicates that the pulse width is close to what is should be for a "modified sine" inverter.

Nooo!! For a 20ms cycle, the ON time in each direction must be about 7ms for the crest factor to come out correct, so that both the RMS and the peak voltages are the same as a sinewave. Otherwise you could equally well apply a 200 microsecond pulse of 11kV in each direction, which gives a perfectly reasonable 220VRMS
 

Online oPossum

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Peak voltage is only about 15% high. Put a load on it and you will probably see the peak voltage go down and the pulse width increase.
 

Offline Tom45

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The various Cyberpower units that I use have always been trouble free over the years.

I wonder if the 240 volt units are more prone to trouble due to marginal design at the higher voltages compared to the 120 volt units that we use in North America.
 

Offline David Hess

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I used to have a trusty old Liebert doing the same job, but that finally died after 20 years service (several battery replacements, of course).

My last three UPSes have been refurbished Lieberts.  They all still work.
 

Offline james_s

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I just did a quick check during my lunch break. This is a Tripp-Lite Internet750U which I've had in service for about 2 years. It's certainly not something I'd use to power life support equipment and like any other UPS that uses those poor little tag terminal SLA batteries I would not load it up to anywhere near the claimed 750VA rating but for what I've asked of it, it has reliably delivered. Looking at the RMS and pk/pk values they look pretty reasonable to me. It's possible that most of these things are designed for 120V and then tweaked a bit to make them kinda sorta work ok in 240V land, I really don't know. As with most things in life, YMMV but I would not hesitate to recommend one of these to somebody with a similar use case as my own, which is keeping about 60W of IT gear running long enough for me to finish what I'm doing and then get out my generator and set it up at a leisurely pace.
 

Offline NiHaoMike

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With your networking equipment it likely will run fine off 12VDC, so a simple UPS would be to have a regulated battery charger and a 12V battery, and connect the equipment to this instead. Easiest way to do this is to look for a security system power supply, which has a power supply that charges a SLA cell, and also provides operating current for the cameras and DVR from the battery. Lowest losses, though the charger/power supply will lose around 5w in operation providing the regular load.
Use 3S 18650 packs, cheaper than sealed lead acid (especially for small packs) and matches more or less perfectly with 12V - about 4V/cell.
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Offline redg

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Use 3S 18650 packs, cheaper than sealed lead acid (especially for small packs) and matches more or less perfectly with 12V - about 4V/cell.

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.
« Last Edit: May 26, 2021, 11:17:44 am by redg »
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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.
 

Offline 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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Offline 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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Offline 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.
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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!
 

Offline 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.
 

Online 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/
 

Offline 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.
 

Offline 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
 

Offline 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.
"Heaven has been described as the place that once you get there all the dogs you ever loved run up to greet you."
 

Offline 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".
 

Offline nfmax

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I think your analysis of the use case matches the mindset of most low-end UPS manufacturers!

Some background:

I have just had FTTP Internet installed to my house. I can use this for, among other purposes, VOIP telephony in place of the existing PSTN copper service. However, in that case with no local power, the phone service would stop, meaning that for example I couldn't call up the power company. So I want to be able to keep the FTTP service up for an extended period. The RasPis I'm not so bothered about, provided they shut down smoothly. The existing FTTP collection of equipment takes 18W, with no PoE load other than the WiFi access point. Obviously, VOIP phones will add to this load, and I plan to add a couple of security cameras as well. But 35W would cover it comfortably.

The classic 'enough power to shut down a PC if the power fails while I'm using it' is covered by a different UPS, in another place. In fact, the Mac Mini is low enough power to keep going for quite a while, although the monitor isn't. Nevertheless, I have this set up to just shut down after a short delay, when the power fails.

The networking equipment is in a central wiring closet, which is quite small and has limited ventilation. It's not really feasible to increase the space or move it elsewhere. There isn't space for a rackmount UPS, unless it's only 8" deep!

Mobile phone coverage here is marginal, at best

Interestingly, BT, our phone company, will stop supplying new PSTN phone lines from 2025 on - they are trialling this now in nearby Salisbury. All (new) telephony service will be VOIP over either fibre or copper DSL, even if no Internet service is provided. From this date, if a PSTN line fails, it will be replaced with VOIP, not repaired.

There are going to be millions of customers who will suddenly discover that if their power fails, so does their phone. At least some will want a UPS...

 

Offline madires

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... if the telco's DSLAM/MSAN/BNG/OLT/CMTS is protected by a UPS too. Otherwise it won't help to have a UPS at home.
 

Offline nfmax

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True, but the same applies to the PSTN Exchange/Central Office
 

Offline james_s

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I would expect any service provider to have not only UPS's on their infrastructure but a backup generator. Certainly my internet has never gone out during a power outage, even the once in 10-15 years where a power outage lasts several days after a major storm I still had internet provided I could power the equipment at my end. I don't think it's unreasonable to have a UPS set up at home providing something approaching "mission critical" reliability, I have managed to achieve that. The UPS's will keep my router, ONT (fiber terminal), switch, security cameras and NVR, and my Plex server and the Raspberry Pi that runs my home automation going for over an hour on battery power. So far that has given me ample time to get out my generator and get that going, there has only been one incident so far when I happened to not be home and a freak autumn storm knocked the power out causing about 15 minutes where my security cameras weren't working. I also don't think it's unreasonable to expect a device to not burn your house down, regardless of whether it's consumer or enterprise grade.
 

Offline nightfire

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About quite exactly 20 years ago, in the demise of the then so called "new economy bubble" I worked at a internet company that also did some transmission stuff (read: fiber lines).

Usually back then, telco equipment was powered by 48V, and every repeater in a container in a field would have some small battery unit to cope for 4 hrs. In bigger Centers (usually built as a POP (Point of presence) you had bigger batteries, but in lots of cases no diesel backup generator due to a variety of reasons.
In germany you had those POP build in commercial buildings some years after the building had been built, so equipping with some diesel generator is/was in lots of cases no option.
Also maintenance and setup of the whole switching gear is expensive, and mostly a POP runs unattended.

 

Offline fordem

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I think your analysis of the use case matches the mindset of most low-end UPS manufacturers!

If that was in response to my post, then you would be incorrect - it's more a matter of stating what is obvious to someone who is in the business of supplying & maintaining UPSs - and for the record, I don't supply low-end UPSs - I do 6kVA and upwards, all the way out to 250kVA - and those generally don't come as anything other than double conversion.

Quote
Some background:

I have just had FTTP Internet installed to my house. I can use this for, among other purposes, VOIP telephony in place of the existing PSTN copper service. However, in that case with no local power, the phone service would stop, meaning that for example I couldn't call up the power company. So I want to be able to keep the FTTP service up for an extended period. The RasPis I'm not so bothered about, provided they shut down smoothly. The existing FTTP collection of equipment takes 18W, with no PoE load other than the WiFi access point. Obviously, VOIP phones will add to this load, and I plan to add a couple of security cameras as well. But 35W would cover it comfortably.

I've had FTTP internet at home since 2017 - my ISP supplied an ONT (Optical Network Terminal) with it's own DC supply which includes a backup battery, the sole purpose of which is to keep the ONT and it's associated VoIP phone(s) & wireless access point working in the event of a power outage, I believe the estimated runtime on battery is in the region of seven hours, the longest I've seen it run without power, I believe, has been four hours - I should point out here that there no inverters to be concerned about, this thing runs on DC power, fed from a battery which is charged when there is utility power.

Perhaps you should check with your ISP to see the ONT they use can accept a similar DC supply, most of them can - that is the nature of telecom equipment.

For what it's worth - my network equipment is mounted in a standard 19" rack, powered by a 1400VA rackmount UPS, with SNMP card, configured to shutdown all connected loads after fifteen minutes on battery, which gives me enough time to walk out back and turn the key on the standby generator.  My desktop is powered by it's own 750VA UPS, again, with SNMP card, again configured to shutdown the connected loads.  These two UPSs, by the way, are eighteen (18) & fifteen (15) years old respectively, and apart from needing the occasional battery change have been phenomenally reliable, they may be installed in a home environment, but they are not 'bottom of the barrel' consumer grade.

As I've been saying, you get what you pay for, and if you need something better, then you can expect to have to pay for what you want, and that includes the operating cost.
 

Offline james_s

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My old ONT had a backup battery although it only powered the part of the ONT that handled the phone which was useless to me once I no longer had a landline. The new ONTs that Ziply (FIOS) is installing now don't have a battery by default although you can get a hokey battery box that takes a pile of D cells.

There's a significant range between true NEED as in mission critical, someone might die or be greatly inconvenienced by downtime and "need" as in really nice to have but not life or death critical. I "need" my internet to be reliable and ride out a power outage, giving me ample time to set up my little generator. If it does go down that is annoying but not a major catastrophe, thus a freebie (plus cost of a new battery) consumer UPS was a perfect fit for me, so far it has done exactly what I expected of it and my router uptime was over 300 days when I last rebooted it to change some settings. That was over the winter when I experienced 3 power outages of a few hours each and numerous brief glitches during storm season which would have been just enough to reboot everything which is annoying. It has given me perfect uninterrupted service while drawing only 2.5W standby, I can't see why I'd want to consider anything else. There are diminishing returns on additional operating expense.
 

Offline nfmax

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Which manufacturer and model is that?
 

Offline james_s

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The one on my router (and ONT, switch and security cameras) is a Tripp-Lite Internet750U, pretty typical inexpensive consumer UPS but it does the job. Only thing I don't like about it is you have to take it apart to change the battery.
 

Offline David Hess

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The FCC has regulations requiring backup power for various public systems, which has become more important with the advent of cellular communications, but I suspect the regulation do not actually require upkeep because I now see a lot of systems with battery backup and worn out batteries.

When I had landline phone service provided through AT&T U-Verse, they included a battery backed up power supply but no instructions for battery maintenance.
 

Offline james_s

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FIOS (Verizon sold to Frontier, sold to Ziply) used to provide a battery backup unit that used a 12V SLA batter, customer is responsible for maintaining it, the unit will start to beep periodically when it fails. Verizon would happily sell you a battery for around double the cost of purchasing one anywhere else but I don't know how many people actually replaced it. At some point they stopped offering the battery backup unit, probably because people would call support every time the thing started beeping. I removed the beeper from mine and plugged the whole thing into a UPS when the original battery failed. I have the UPS anyway because it keeps my router powered, otherwise a momentary power glitch results in several minutes delay while it all reboots.
 


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