In my opinion for UPS:
1. Eaton/Powerware
2. Emerson/Liebert
3. Schneider/APC
4. ---- Stop reading this list here ----
5. Everything recommended on other computer forums like hardforum. Don't plug no-name products into mains voltage. Cyberpower and Tripp Lite are low-end brands. Heck they literally sell UPS that aren't supposed to be used with PSUs that have power factor correction... even though almost every PSU has that these days.

We use Eaton 5PX and 9PX at work and they are absolutely terrific. The battery lifespan is longer than the older APC units we had and the older APC units we had would literally refuse to use a new battery pack until you calibrated it, and to calibrate you need to turn your servers off, hook up a halogen light bulb (or other ~500 watt constant load - can't use servers because the power load of those changes with the load on the servers), and let it drain the batteries. I also have an APC SUA2200RMXL at home which does the same - I lost power for over 5 days a few years ago due to a hurricane. I had that UPS and 2 car batteries and I hooked it up and the UPS artifically shut off the load while barely touching the batteries, and yes they were good batteries that I charged. Whoever at APC made that decision clearly had never thought about having to use a battery backup in a semi-emergency situation and I'm getting downright angry just thinking about it. I still own that UPS but I currently use an Eaton-built Dell K788N which is a 1000W model that works pretty well. It's a bit loud for home use but not unacceptably so, and nowhere near as loud as my SUA.

I've never used a PW5125 (though I did consider buying one). Those are older, but should still be good units. I would have no issues buying one. You could also look up the Dell K788N; I would recommend that as well as long as you can deal with an online UPS that runs its fan all the time. You can mod it and put a variable RPM fan that uses a temperature sensor but make sure that it will still blow enough air when the machine is warm.

Do keep in mind that most UPS are rated in VA, and the actual watt rating varies depending on the unit but is generally about 70% of the VA rating. (Yes, 70.7% is sqrt(.5) but not all units use that conversion.)

There is no general conversion from VA to watts, because it depends on the power factor of the device in question. With a modern ATX PSU your power factor will usually be above 95% (heck, they'll hit about 99% under some circumstances) so that's no big deal, but you'll still have to base your UPS sizing on the watt rating, not a VA rating.

A small number of UPS like my Dell one are actually rated in watts, though, so that wasn't a mistake on my part.

Edit: Oh and as far as refurb goes, the good thing is that most UPS use one of 3 sizes of batteries: ~5.5AH, ~7AH/9AH, and ~12AH. Those are of course capacities but each of them has a standard physical size (note: I said "7AH/9AH" because typically that physical size battery was always 7Ah but some manufacturers sell batteries rated 9Ah in the same physical form factor. Similarly, the 5.5AH batteries are sometimes 5AH or 6AH as well.). And if you're willing to buy a mediocre battery brand like Gruber then you can get any of these quite inexpensively. Whatever brand you go for, make sure you get AGM batteries. Never consider flooded/wet cell (which isn't durable for use in a UPS and can also offgas) or gel cell (gel cell voltage is around a quarter of a volt off from flooded cell and AGM, and AGM is still more durable).

Thanks for the info. I was thinking of putting a different fan in whatever unit I buy. I was think something like one of noctas fiberglass industrial fans and add a temp sensor to it.

I do work on ups at work, manly cheap small Apc units, I hate those. So I know a bit about them. But not a hole lot.

Jade Falcon wrote:

Thanks for the info. I was thinking of putting a different fan in whatever unit I buy. I was think something like one of noctas fiberglass industrial fans and add a temp sensor to it.

I do work on ups at work, manly cheap small Apc units, I hate those. So I know a bit about them. But not a hole lot.

The larger UPS are pretty much the same except that they have more buttons (might take you a couple minutes to figure out how to turn one off) and you have to remove a few more screws to get to the batteries (and there are of course multiple batteries). I actually just opened the ones here this week... 2-4 screws instead of 1 screw, heh.

Also with enterprise equipment it's generally easier to find PDFs of manuals compared to some consumer stuff so you should be fine with getting the information you need.

I've only fanmodded one UPS so far, a Liebert GXT2 which was a rackmount unit, and I found that to be quite straightforward and you probably also would have no trouble with it. Just make sure you're not putting in a low-speed fan. Either stick to a fan that blows about the same air (but maybe has a higher quality, quieter bearing), or just add some sort of sensor-based speed control to it. You can buy fans with sensors built in. Not sure if Noctua sells any.

BTW if you look up APC, for cheap old-looking units you'd find probably the SU1400NET (which was my first UPS, used of course), which is OK for its age but will likely absolutely insist on new batteries being calibrated. Wouldn't recommend the unit with its age at this point, though. You should be able to find one for practically free at this point and it would look the part. I think they made some SUA* models in beige, as well. SUA is newer than SU*NET. But even the SUA stuff will be annoying about calibration. Some of the SUA stuff is also black but I think they had beige in the early lineup. You should definitely go with that Eaton over this though.

I have worked on a an large apc battery that for my works server. I agree there about the same, just bigger and with more buttons.
Personally I rather stay away from any apc backups.
As for the fan, I was going to get a retro kit that adds a temperature controled automated speed controller to the fan. I'll post a picture when I find one.

This is what's I was thinking of useing for the fan.
http://www.frozencpu.com/images/products/large/tmp-30_2.jpg

That's interesting about issues with APC units. I've had second-hand rackmount APC units as home UPSes for years and never encountered a situation where I needed to calibrate them. Just got replacement batteries, wired them up, plugged them in and good to go. Didn't even have to shut off the UPS or the connected load. My understanding is that calibration is only used to get a more exact idea of how long until the batteries go flat, but since I don't bother shutting my PCs down automatically (I just use the UPSes to ride out any short blackout) I've rarely bothered with calibration. You don't need a 500W load to calibrate, but APC recommend you load the UPS to at least 30% to do it. I never bothered and just left the PC connected during calibration (was like 10% of load) because I figured that was going to be the same load that it would see when running on battery, and never had any problems. It was a bit over cautious though and warned me about imminent power loss about 15 minutes before it actually shut off from a low battery, but I can live with that.

This was a 3000VA unit (8x 7.2Ah batteries) and it was able to power my PC, monitors, DSL modem and server for about an hour on battery.

One thing I did notice however is that as the batteries near the end of their life, they are unable to deliver a high current anymore. They eventually reach a point where switching on the inverter pulls so much current that the battery voltage drops too low, and the inverter shuts off again and the UPS powers off (if there's no mains available.) It sounds like this is what @kenrouholo may have experienced trying to get the UPS running off other batteries. If they weren't brand new, it doesn't surprise me that the peak current of switching the inverter on caused the battery voltage to sag so much that the inverter couldn't start, even though the batteries may have worked fine for supplying lower current loads. I find it kind of irritating that you have to "throw out" old UPS batteries that are still quite serviceable for low current applications, just because they can't service that peak when the inverter switches on. I'd rather see a UPS design with some large capacitors to avoid this surge, but I guess for enterprise gear they'd rather make more sales from battery replacements instead...

I've often wondered whether a dual conversion UPS would eliminate this (one where the inverter is running all the time) but I haven't seen one of these second hand so I suspect they aren't that common.

If going the APC route (which is the only one I have experience with) I'd recommend finding one with XL in the model number, as these have larger power supplies and can take up to 10 external battery packs, if you ever want to extend the run time. The non-XL units can only handle their internal batteries, and APC warn that manually increasing the battery capacity on these units (e.g. with custom cables) risks overloading the power supply.

APC units can be had for quite cheap, as they do not switch on unless there is sufficient charge in the batteries. This means many APC UPSes are sold as not working/for parts because they won't turn on, but replacing the batteries is often all you need to return them to service. If you're handy, you can also disconnect the batteries and stick 24V/48V DC (depending on the model) onto the unit's battery connectors for a minute or so to charge up the capacitors, then disconnect that, plug in the mains, and there will usually be enough charge for it to have one go at switching on. Usually there's limited use to this though, because even if you reconnect the original batteries so they can charge, they don't hold much of a charge for very long anyway. But at least it's a quick way to check whether the UPS is still good.

I have a beige 1400VA Smart-UPS XL that I bought for $6.50 because it wasn't working, but new batteries was all it took and it's been going fine for years now, currently powering the PC I am typing this on. If you're located near Brisbane, Australia I have a couple of batteryless beige 3000VA rackmount Smart-UPS units I wouldn't mind getting rid of...

they were only about 2 year old high quality car batteries (Deka Intimidators) removed from car audio cars that were sold... I mean yeah I'm sure they weren't in top condition but they were not bad or anything

my SUA2200XL as well as my Dell K788N are both online.. so was my GXT2.. only tried car batteries in the SUA2200XL though. Probably going to add some 18Ah batteries to my K788N (which happens to take 36v so 3 12v or 6 6v but 12v 18Ah are fairly cheap)

Almost any UPS that runs its fan all the time is online ("double conversion"). There are most likely some exceptions to that, but I can't think of any offhand.

Best bet is Eaton 9120, it really looks like a old server.

I use APC Back-UPS 500, beige colour. I bought this in unit in 1997 or 1998. It has gone through only two battery replacements. It has a serial cable, so it works with pre-USB computers to shutdown your computer after X minutes or with X battery juice remaining via a serial cable. Works in NT4. It used to be hooked up to my 486 file server, which I have shutdown now. It was fun to run file servers before free GB's were everywhere online. The UPS is now used to keep my AMD Opteron 185 from crashing during a power outage.

If you know of a more vintage beige UPS with batteries still available for them, please post a photo.

I also second the older APC units like the Back-UPS 500. You can find a LOT of half decent old UPS units available often for their (batteryless) weight at scrapyards. Finding replacement batteries is not that hard.

Any ups + deep cycle golf cart batteries. Use standard charger to top the batteries off and the ups will float them. Till they are needed

kenrouholo wrote:

Almost any UPS that runs its fan all the time is online ("double conversion"). There are most likely some exceptions to that, but I can't think of any offhand.

In my experience some of the bigger APC SmartUPS units (2200VA and larger) will run the fan all the time, and those are line interactive just like the smaller units. Probably to keep the inverter or batteries cool while it's maintaining the larger batteries.

FesterBlatz wrote:

kenrouholo wrote:

Almost any UPS that runs its fan all the time is online ("double conversion"). There are most likely some exceptions to that, but I can't think of any offhand.

In my experience some of the bigger APC SmartUPS units (2200VA and larger) will run the fan all the time, and those are line interactive just like the smaller units. Probably to keep the inverter or batteries cool while it's maintaining the larger batteries.

Well, damn, you're right. I was told the 2200XL was online when I bought it; it's actually line interactive as you said. I can't believe I fell for that BS :( Well at least it's pretty darn quick to transfer to battery. Good thing I got it for a great price, used of course.

It's like they can't do anything right. I like APC less and less every time I actually look more into them. This UPS was about $1000 new and it's friggin line interactive. Argh.

Glad to be using my Eaton UPS primarily.

For power we use APC almost exclusively at work, including a 3-phase Symmetra PX in the datacenter as well as a 150KW standby Cummins generator I got from Schneider Electric that's bundled with an APC ATS. They've all been workhorses!

The Symmetra is great, everything except the static switch is N+1 and hot-swappable. And the capacity can be upgraded in 10KVA increments by sliding in additional power modules. Even the matching PDU's in the racks are cool, there's a digital LED readout that shows exactly how much current you're drawing on each phase to help keep things balanced and you can monitor them with SNMP over Ethernet as well.

For cooling, I'll only use Liebert though. 😀

And yes, EATON is definitely a top-knotch name in UPS as well. I've been in several telephone company switch buildings that have dozens of Volkswagen sized EATON's protecting their equipment, as well as their co-located customer's racks as well. So I definitely have lots of respect for EATON. Heck, the breaker panel in my house is made by EATON.

FesterBlatz wrote:

And yes, EATON is definitely a top-knotch name in UPS as well. I've been in several telephone company switch buildings that have dozens of Volkswagen sized EATON's protecting their equipment, as well as their co-located customer's racks as well. So I definitely have lots of respect for EATON. Heck, the breaker panel in my house is made by EATON.

haha... I actually swear by Square D (owned by Schneider Electric) panels and breakers (particularly the QO line) - same company that owns APC. I would be fine with Eaton equipment too, though.

Didn't APC go downhill after Schneider Electric acquired them?

feipoa wrote:

Didn't APC go downhill after Schneider Electric acquired them?

I don't know but I've used APC UPS from around the mid or late 90s to the late 2000s (and newer, but only the super entry-level "chunky power strip" type ones lately, as we buy those at work for use at workstations) and I'd take the newer ones for sure. More intelligent charging, better battery life, though still not as good as Eaton or Liebert in my experience.

Let's not forget, also, that APC has actually had to recall power strips (not UPS, literally just power strips / surge protectors) in the past. http://recall.apc.com/en - not aware of this being an issue with Liebert or Eaton power protection stuff. Honestly I don't let this scare me very much, though. They're old models and honestly the actual risk on them is not that bad. But still, a recall on a power strip does not instill confidence in the brand.

Thank you for sharing that recall link. I have one of the surge protectors featured in that list. This is a lot of surge protectors manufactured before 2003. I've used that surge protector for 15 years without incident.

feipoa wrote:

Thank you for sharing that recall link. I have one of the surge protectors featured in that list. This is a lot of surge protectors manufactured before 2003. I've used that surge protector for 15 years without incident.

Oh damn, that was quite unexpected. I was worried I was being a bit "too negative" talking crap about them but glad to know it's useful info.

Maybe they'll send you a replacement but if not I personally like Furman and Panamax, but especially the Furman models that have both MOVs and series-mode protection (Series-mode can also be found in Brickwall, Zerosurge, etc.)

You should be fine with it as long as you don't overload it but, eh, it's getting about time to replace it anyway (components inside such as MOVs can wear out over time slowly even without major lightning incidents)

It so happened that I pulled that surge protector out of operation about 18 months ago. I wanted to have battery backup power for my network's server closet (router+modem+switches+NAS hard drives).