Back UPS and PFC Power Supplies

[Anonymous user]

I am quoting Erasmus from a post made almost a year ago, on 4/27/2009:

"Starting in mid 2008 all of our Back-UPS products being manufactured were revised to better handle load requirements for PFC devices, both through small firmware and hardware revisions. This allows the majority of Back-UPS being manufactured now to handle most (not all) PFC loads within their wattage range much better than older units. Their output is still stepped-approximated, however, and we still find the occasional PFC device that they have trouble with, especially those with high inrush currents or those that are just plainly "oversized" in relation to the UPS."

For the full discussion, see: http://forums.apc.com/spaces/5/smart-ups-symmetra-lx-rm/forums/general/2271/couple-questions-just-go...

Does this mean that APC will honor its warranty when a properly-sized Back-UPS is used with a PC that has a PFC power supply?

"This allows the majority of Back-UPS being manufactured now to handle most (not all) PFC loads within their wattage range..."

Which specific models of Back-UPS are not included in "... the majority of Back-UPS being manufactured now..."?

[BillP]

There isn't a comprehensive list of power supplies that are considered "compatible" with the Back-UPS products. Your best bet would be examining the power supply's requirements in terms of step-approximated vs pure sine waves - that seems to be the latest obstacle. Some computers will work fine with a Back-UPS product until it's had time to "break in," at which point the step-approximated sine wave offered by the Back-UPS won't suffice.

Using a PFC PSU with a Back-UPS won't void your warranty or anything, but it isn't considered a product defect if it doesn't keep your computer on (assuming it DOES power other things for testing, like lamps, radios, etc). The units are better designed to attempt to handle newer technology and PFC requirements, but at the same time, PSU manufacturers are doing the same by making units that have higher demands for proper functionality.

Personally, I've heard Enermax PSUs don't like anything less than a pure sine wave... Along with some HP systems (I've had issues with the HP DC5800 in particular) and some Dell XPS systems. And, of course, servers. My OCZ 600w PSU works fine - it's on a BR800BLK. I know someone with an Antec that buzzes obnoxiously but otherwise works fine (also on a BR800). The PSU manufacturers would be the best source, though.

I wouldn't suggest a BE model. They've got the longest transfer times and the smallest capacities. I'd recommend something in the BR line for a PFC unit, though still, some PSUs don't like the step-approx sine wave, so it may not work for sure.

[Anonymous user]

"Why rule out the Back-UPS as an option for everyone when it works for many users..."

For many users...but not for all. Don't you feel that APC has a responsibility to inform consumers that a Back-UPS unit may not power their computer or cause it to reboot if the computer has a power supply that requires a pure sine wave UPS? Otherwise, do you feel APC is misleading consumers by recommending Back-UPS units?

If a customer buys a correctly sized Back-UPS from APC, tests the UPS on their PFC-equipped computer, and discovers that the Back-UPS either does not provide power or causes their computer to reboot, will APC issue a full refund upon return of the unit in re-saleable condition?

[Anonymous user]

Increasingly, home and small office computers are shipping with power supplies that are not compatible with the UPSes that APC markets to home and small office users. This trend is not going away.

Where does this leave the consumer?

I have yet to read a statement from APC saying: "Attention - If your computer has a PFC power supply, do not purchase a UPS from the Back-UPS product line. Only a Smart-UPS product will protect your computer."

Instead, I have read a lot of hemming and hawing and hedging...yes, the Back-UPS were improved in mid-2008 to work better with PFC power supplies, but we're still seeing problems, sometimes...yes, your warranty is still good, even though Back-UPS was not designed for your power supply/no, your warranty may not be good...

When is APC going to step up to the plate and tell consumers the straight story?

[BillP]

Like I said, it depends on the PSU manufacturer - it's not just whether or not the PSU has PFC. The PFC factor alone mostly just requires a bit of oversizing to allow for inrush current. The issue is the sine wave. If a manufacturer says "this PSU is not designed to work on a step-approximated (or otherwise modified) sine wave," then it won't work with a Back-UPS. My PSU IS PFC and it works fine with a Back-UPS. Why rule out the Back-UPS as an option for everyone when it works for many users and is not a flaw with the UPS itself?

I kind of doubt people would be happy stepping up to a $300 Smart-UPS for their home computer simply because APC assumes no PFC PSU can operate with a step-approx sine wave, especially since that isn't the case. And the Smart-UPS (and higher) models are the ones that produce a pure sine wave.

I think it leaves the consumer in the position most find themselves when trying to make the "right" purchase - having to do a bit of research to make sure it's what they want/need. I can't speak for everyone, but I hope people don't just grab a random camcorder off the shelf and wait to ask questions until they're on vacation trying to use it. APC's number is 800-890-4272 for anyone who wants a recommendation, or help getting started in the right direction to know what questions to ask.

[BillP · Accepted solution]

Don't you feel that APC has a responsibility to inform consumers that a Back-UPS unit may not power their computer or cause it to reboot if the computer has a power supply that requires a pure sine wave UPS?

Yes, definitely. Anyone who calls into APC for sizing will field questions about the equipment going on the UPS, one of which is about the pure vs modified sine wave. Hopefully customers are willing to take the time to do the research with APC, either knowing this beforehand, following through with PSU manufacturers to find out, or working with APC on the phone to find out the specs needed.

Otherwise, do you feel APC is misleading consumers by recommending Back-UPS units?

If someone at APC recommends a Back-UPS product for a computer knowing that it needs a pure sine wave, that would obviously be misleading. I don't think anyone would do this intentionally, though not asking the right questions could pose an issue.

If a customer buys a correctly sized Back-UPS from APC, tests the UPS on their PFC-equipped computer, and discovers that the Back-UPS either does not provide power or causes their computer to reboot, will APC issue a full refund upon return of the unit in re-saleable condition?

As long as it's still within the 30 day return period, of course. There's usually a 15% restocking fee on returns, but it's possible for that fee to be waived. It's not the customer's fault if someone at APC recommended the wrong unit (though a case number - provided for every sizing call - would help back up your story). I'm assuming by "correctly sized," you meant it was recommended by APC. However, if the customer bought it without contacting APC to ask about compatibility, the fee wouldn't likely be waived.