Pure sine wave UPS

[Executor_]

I've currently got a APC Back-UPS RS1000 that I bought back in late 2004. I bought a new computer in December 2009 and since then I've had issues with (probably) power surges causing the UPS to switch to battery backup, and then a second or two later my computer turning off and the UPS emitting a shrill beeping noise. Now this only happens maybe 20-25% of the time the UPS switches to battery backup, but that still means my computer turns off once or twice a week and it's kinda annoying. From what I've read it's caused by my new computer having one of these new-fangled active PFC power supplies. Can anyone recommend me a good UPS that outputs true sine wave while in battery backup mode that is in the more affordable range, say $150-200? I've heard that APC's Smart-UPS series is pure sine, but I'm not sure which of Cyberpower's, Tripp Lite's, or the other manufacturers are.

The max power draw for my computer is ~540W, as reported by my UPS while simultaneously running Furmark + IntelBurnTest on my Core i5-750 OC'd to 3.61GHz, Radeon 4890 OC'd to 950MHz/1080MHz RAM, 3 hard drives, and a 28" monitor. There's also a DSL modem and router attached to the UPS. Most of the time though, the power usage should be a lot lower, even while gaming.

 

[SunnyD]

Something like this?

I seriously doubt even that is "pure" sine wave. It's still probably simulated stepped sine, just with a lot more steps.

 

[Modelworks]

Almost all the low end ups will be modified sine wave, looks like a sine wave and a square wave had a baby

Most things are okay with that and your pc supply should have a problem with it. To get one new for that system you are going to spend about $5-700.00 .
I would look at the different online refurb dealers where you can get good pure sine ups for less than half that.

New this is the lowest I could find that seems to be a quality product. $412
http://www.newegg.com/Product/Produc...82E16842570016

$369 for cyberpower unit but I never liked their build quality as much.
http://www.tigerdirect.com/applicati...4994&CatId=234
Watch out for ones that have high output wattage but are small in size because that also means the batteries inside are small. Under heavy loads the battery lifespan will be short because you are discharging it almost completely every time. Also make sure it says PURE sine wave and not just sine wave.

 

[SparkyJJO]

You know, you may just have dead batteries too.

I have an APC Smart-UPS 1000 here, pure sine, but the batteries are weak. I actually get a longer runtime out of my old Smart-UPS ES 725 lol. So my PSU buzzes a little when on battery, since the ES doesn't have pure sine output... big deal...

 

[Meghan54]

Can anyone recommend me a good UPS that outputs true sine wave while in battery backup mode that is in the more affordable range, say $150-200?

The simple answer to that question is they don't exist.....but there's no reason a sim. sine wave UPS wouldn't work with your active PFC power supply. My Corsair 850HX works very well with my APC Back-UPS 1200, which is not a true sine wave UPS. Lasts maybe 10 min. or so at idle.

But, as Sparky mentioned, your batts are probably toast. Have yet to have an APC UPS's batts last 6 years without needing replacing. Sad, but true.

 

[Executor_]

The reason I doubt it's a problem with the battery is because 75+% of the time when the UPS switches to battery mode it does so perfectly fine. Sometimes though, I'll hear my UPS begin making the buzzing noise signifying it's going onto battery, and then a second later my entire computer turns off and my UPS is making a beeping noise. I then have to press a button on the UPS to reset it before I can turn on my computer. From what I can gather, a quarter of the time when my UPS transitions to the stepped-sine battery mode, the PSU on my computer doesn't like it or tries to draw too much power or whatever, so the UPS senses an overload and turns itself off. The UPS shutdown issue only happens within a couple seconds of a switch to battery power, never after that. There was a power outage several days ago that lasted for a few minutes, the UPS took over and my computer stayed on. If the battery was dead, what kept my computer powered? Also, this issue only arose after I bought my new computer with the active PFC PSU. The UPS never turned itself off when there was a power irregularity when my old computer was hooked up to it.

How decent are these two UPSes? I think they're cheaper versions of the Cyberpower UPS ModelWorks suggested.
CyberPower Smart App PP800SW 800VA http://www.onhop.ca/catalog/product/10285556 Can$220
CyberPower Smart App PP1100SW 1100VA http://www.onhop.ca/catalog/product/10285558 Can$260
The second one has bigger batteries, but for only $40 extra it might be worth it. They both seem reasonably priced considering it says their output is pure sine.

 

[Mark R]

Your UPS is only a 600 W UPS - if you are running 540 W of load off it, then you may well be exceeding the capability of the UPS.

A low-end UPS like the back-UPS waits for the power to go out, and then activates battery power. This leaves your PC and other equipment unpowered - during which time they drain their capacitors. When the battery kicks in, the capacitors have to recharge - and the combined load for the first second or so, may be too much for the UPS.

True sine wave isn't that big a deal - but it is an expensive, industrial grade feature - and so tends to be found only on better quality UPS units. It's not a necessity, as good quality modern PC PSUs are incredibly tolerant of very noisy and poor quality power (they just don't cope with interruptions).

The active PFC is a bit of a red herring, I think. APFC is very tolerant of non-sine waveforms. However, one of its advantages is that it allows a significant increase in the energy storage capability of the PSUs capacitors, so this could mean a higher temporary surge after a power interruption (like when the UPS changes to battery mode).

 

[Executor_]

Your UPS is only a 600 W UPS - if you are running 540 W of load off it, then you may well be exceeding the capability of the UPS.

The 540W is the maximum possible power draw for my entire computer, but I noted that was hardly normal since that involved running Furmark and IntelBurnTest at the same time. While websurfing, for instance, the UPS only reports a 220W power draw, and even while playing Crysis Warhead it's only around 420W.

 

[SparkyJJO]

The simple answer to that question is they don't exist.....but there's no reason a sim. sine wave UPS wouldn't work with your active PFC power supply. My Corsair 850HX works very well with my APC Back-UPS 1200, which is not a true sine wave UPS. Lasts maybe 10 min. or so at idle.

But, as Sparky mentioned, your batts are probably toast. Have yet to have an APC UPS's batts last 6 years without needing replacing. Sad, but true.

So, are you saying APC or others are lying when they say "true sine wave output" ? Now I wish I had an O-scope so I could test the output of this Smart-UPS 1000 I have sitting here.

6 years is a long time for any UPS battery, IMO, especially if it gets used a lot. I'm at 4 years with mine so far, runtime is reduced a little but not bad, yet.

 

[Modelworks]

So, are you saying APC or others are lying when they say "true sine wave output" ? Now I wish I had an O-scope so I could test the output of this Smart-UPS 1000 I have sitting here.

6 years is a long time for any UPS battery, IMO, especially if it gets used a lot. I'm at 4 years with mine so far, runtime is reduced a little but not bad, yet.

I think what he is saying is that they do not exist in the $150-200 price range. I have looked at outputs of higher end ups with pure sine wave and they are perfect in that regard.

Almost every ups I have seen that is 3 years + have failing batteries for the same reason. The batteries dry out. The batteries in a ups are normally SLA or sealed lead acid, but they are not totally sealed for safety reasons. If you look at a SLA battery on the top you can see plastic covers that conceal each cell in the battery. You can pop those off with a knife, they are usually glued in place. Under that is a small rubber cap. The cap is in place to keep the acid in the battery. When the battery is charging it produces gas. That gas floats to the top of the cell where the cap holds it in. Once charging is over the gas is re-absorbed into the electrolyte. Over time and multiple charge and discharge cycles the rubber caps start to not seal so well. Each time after that the battery is charged a tiny amount of gas is released. Eventually the electrolyte level falls too low and the cell becomes weak. Since the cells are wired in series , one cell failing can cause any cell after that to lose current. An ideal battery would be totally sealed but that isn't possible because if a battery were overcharged it would explode because the gas cannot get out. So they design SLA with a threshold where if it does overcharge, the rubber cap lifts, the plastic cap comes off and the battery vents. Unfortunately over time it also leads to dry cells.

What you can do if you catch it in time is refill the cells with distilled water. Pop off the plastic covers, remove the rubber stoppers and use a flashlight to see what the levels are. Top it off with just enough to bring the level back to where it was . Replace the rubber cap and then the plastic cover. I like to use clear tape to re-attach the plastic cover. That lets me see the status of the rubber cap , if it is loose or bad.
I have batteries that are going on 8 years old and working great. Some that only read 9volts when I pulled them. I refilled them and put them on a battery charger and re-attached to the ups and they work fine now.

 

[SparkyJJO]

Interesting. Maybe I should check the batteries in this Smart-UPS I have, since they still work, just weaker. They say sealed so I didn't think it could come apart.

Project!

 

[OrigRalph]

i realize this is an old thread, but figured i'd post this for others doing what i was, researching pure sine wave UPSs. I've got an APC-1000 Smart UPS (1000va, 670W) - their smart series is the upscale line with pure sine wave power. The Backup series is the low end with modified or square sine.

I discovered my APC-1000 is drawing 93 watts constantly with nothing connected - i'm on a "slim down" my electric bill kick, and 93W constant is almost $14 monthly here on my electric bill and ironically, more than my desktop's total draw of 50-53W when browsing or loading heavy programs.

Did quite a bit of research, and it seems the smart APS line is doing an inverter thing, ie even when it's simply supplying power straigth thru from the receptacle, its still doing a line AC to DC to AC out and tha'ts where the power consumption is going. The Backup series, when not on batt power, are simply letting line AC pass straight thru, unfiltered and basically unregulated (or no AVR) - measured a APC 550 draw at 5 watts with no load which is economical to operate even if it's "dirty" power.

when you go to APC's site, on the Smart series UPSs, they show a power efficiency graph - you'll notice the higher the load on the unit, the higher the efficiency. My desktop's draw is 50-53W, which is only .075% of the 670W capacity, so the eficiency is at 63%.

btw, when i called into APC tech svc, they confirmed the APC-1000 normal current draw at .9 Amps / 115V which works out to be 103W

so far the lowest i've found is the Cyber line some linked above, at 510W

in case the above is a consideration for some

i'm in the process of looking for a low watt (250-300W) pure sine UPS - if power goes out, i don't need the desktop to run for more than a few minutes, and considering i just installed a SSD, it shuts down in 15-20 seconds. I've got the APC management program set to shut the system down after 3 minutes to give line power a chance to come back on.

i agree with the earlier comments on battery life - and the deeper you discharge a battery before recharging, the shorter the battery's life. Hadn't thought about checking the level in the SLA batteries, suspect that isn't a bad idea - mine are 4 years old (two 12V 6 AH batteries in series), but checking em with a multi-reader, i registered 14V across each, and 28V across both, so 4 years old they're still in pretty good shape.

 

[Modelworks]

i'm in the process of looking for a low watt (250-300W) pure sine UPS - if power goes out, i don't need the desktop to run for more than a few minutes, and considering i just installed a SSD, it shuts down in 15-20 seconds. I've got the APC management program set to shut the system down after 3 minutes to give line power a chance to come back on.

i

I don't think that low a wattage is made in pure sine wave UPS. Pure sine wave targets larger systems like servers and so they have higher watt ratings. The thing to keep in mind about UPS sizing is that you want at least 15 minutes run time for the load it powers. The reason for that is so that the UPS isn't being stressed and the drain on the batteries will not be excessive. When you purchase a UPS and only have something like 5 minutes run time chances are the batteries for that system are too small and not likely to hold up in the long term.

When you are measuring battery voltage the only way you can tell if the battery is good is to put a load on the battery when you take the reading. A really easy load is a standard 60watt + 110Volt light bulb. Wire up an old lamp or socket across the terminals and then measure the voltage. Ham radio operators have used light bulbs for loads for decades because they work so well and are easy to get.

 

[bryanl]

Every real sinewave UPS or back-up I've seen had that information prominently advertised, but you may want to check for the distortion rating since stepped squarewave models will be rated for about 48% total harmonic distortion (THD), while real sinewave units should be rated for 10% or less distortion. Of course a pure sinewave UPS would put out 0% distortion.