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Do I Have Issues With Watts? ...Between Power Supply & Battery Back-Ups?

By montecarlo1987 ยท 16 replies
Mar 11, 2010
  1. Hello. I have a question. I have a BFG power supply for my desktop that is rated at 800 Watts ATX 12V 2.2/ EPS 12V 2.91 [BFG model: BFGR800WPSU]. I have a APC Back-Ups power supply/battery backups that is rated at 450 Watts / 725 VA (the rating both for output power capacity & max. configurable power) [APC model: BE725BB]. Obviously, the desktops power supply cord is connected and drawing power from the power supply/battery backups for battery backup reasons. My 19 inch LCD monitor is also connected to this power supply/batter backups as well. My desktop computer has Intel Core 2 Quad processor, only 1 NVIDIA graphics card, 1 Creative X-Fi Sound Card, 6 other PCI cards installed, 2 DVD burner drives, 1 floppy drive, 5 hard drives, 5 internal fans + 1 CPU fan.

    Now this is my concern: Do I have issues here concerning my Watts? ...even serious issues? I am not trained and know very little about electricity, but the Watts of my power supply/battery backups is almost half that needed for the Watts for my desktop power supply. Just tonight I have discovered this possible issue. I have been using this BFG power supply for a long time now and have had it plugged into this battery backup system for a long time as well. To date, I have not had any issues. The computer has run just fine. I may be overreacting or I may be NOT! Please comment and state facts about my situation if I do indeed have an issue. Also, if you have any solutions to an issue, please help me! Thanks!
  2. captaincranky

    captaincranky TechSpot Addict Posts: 12,017   +2,054

    Why don't you go here (Antec PSU calculator) , ,plug in your system specs, and you'll likely be able to answer your own question.
  3. Ritwik7

    Ritwik7 TechSpot Chancellor Posts: 1,672   +9

    There should be no problem. However, if you overclock your CPU and GPU and the PSU actually has to pump out over 450 Watts the UPS will start beeping. I had a Powercom UPS rated at 360W / 600VA and everything runs fine on it unless I OC. However, only my PSU is connected to it, not the monitor. I removed the monitor load from the UPS because with my current setup the UPS would beep while playing Crysis / Modern Warfare 2 when the monitor was connected to it.
  4. captaincranky

    captaincranky TechSpot Addict Posts: 12,017   +2,054

    Now Rit, if you don't hook the monitor to the UPS, then you will not be able to see to save any open files, should you have a power failure. This, to me at least, seems to negate the purpose of the UPS in the first place.
  5. CMH

    CMH TechSpot Chancellor Posts: 2,039   +9

    Actually, I think the whole idea of a UPS seems useless to me in such a setup.

    I have a similar powered UPS, and I get about 30 secs of backup power (tested by yanking the cord out :D). And I don't have half as much stuff plugged in, although I admit my computer is OCed quite aggressively.

    Maybe you should evaluate your UPS needs, and upgrade as needed. Yank the cord while running something, and see how much time you actually do have. If its not long enough, then the whole idea of backup power would be pointless.

    However, a low power UPS is still usefull in brownouts, and is still protective against spikes and power blips.
  6. Ritwik7

    Ritwik7 TechSpot Chancellor Posts: 1,672   +9

    Absolutely Cap. That's why I said I had a UPS. Currently not using it since I've OC'd my system. And a good UPS that will serve my purpose is too expensive for me to afford right now. The only power backup I have is an inverter but I've been told on these forums that it does not provide the same amount of protection a UPS can.
  7. SNGX1275

    SNGX1275 TS Forces Special Posts: 10,715   +397

    You are fine montecarlo1987, the UPS shouldn't care how much your peak current draw is when it is plugged into the wall and there isn't a power outage.

    Just FYI Watts = Volts * Amps

    But your UPS won't be able to supply more than 450W (likely more like 420ish) in the event of a power outage. The good news is, unless you are gaming or otherwise heavily taxing your components you won't be pulling more than 420W anyway despite having an 800W PSU. That just means your PSU is capable of delivering 800W (again more like 720ish) if it is required, it doesn't mean its pulling 800W continually.

    So if the power does go out, normally you should have a couple to a few minutes to shut down. This is assuming you don't have a CRT monitor connected to it as well.

    To get a better idea on how much current you are pulling at times I'd recommend picking up a Kill-a-Watt meter, its pretty handy for things under about 1600W (it says its rated to 2000W, but I partially melted mine somewhere around 1700-1800W).

    Also, you can 'hack' your UPS to fit a bigger battery, all it needs to be is 12V. Although for safety reasons I recommend a sealed battery as opposed to a typical car battery.

    And for you guys that don't see the point of UPSs, consider this.. My main PC is connected to mine, and I've got somewhere around 4 minutes of life with it, but in situations where the power has a chance of going out I have it shut off anyway. And I don't leave unsaved files open when I'm not around the computer in case of an unexpected outage (thats just smart in general). But the real beauty of my UPS is that my wireless router and cable modem are connected to it, so in the event of a power outage I still have internet access from my laptops, and the router and modem aren't pulling much at all, so the UPS will last a long time.
  8. Archean

    Archean TechSpot Paladin Posts: 5,682   +86

    @Rit & Captain:

    I have a 500W UPS, with 550W PSU, a case which is slightly like our OP. Interestingly this UPS is now almost 6 years old, and still gives me about 4-5 minutes of backup (monitor is not attached).

    I thought of doing exactly what Rit did, that is to do away with it, but then I found a slightly better use of it, that is, if power fails, I can hit the power off button and system shuts down normally at least. Usually I do most of my critical work on notebook so I need not to worry about what I may loose :)
  9. jobeard

    jobeard TS Ambassador Posts: 9,669   +673

    My setup is similar to SNGX1275; it's a Cyberpower 800AVR with all the network devices, a Mac desktop and my laptop;
    The UPS cable goes to the Mac for early shutdown and the laptop survives on its own.

    Save all files before you walk away or close the laptop is just S.O.P. (std operating procedures).

    The UPS provides two major services;
    1. power conditioning ( removing voltage variations, both +/- )
    2. controlled shutdown
    but is not intended to keep you live when the area has an 8hr brown-out.
  10. captaincranky

    captaincranky TechSpot Addict Posts: 12,017   +2,054

    This is the sort of thing that might happen when you test a 15 amp power saw while cutting a wet pressure treated 2 X 4. In cases such as these, I humbly suggest you take the power saw label's word for it.
    Here, at least consider the possibility that the UPS's onboard charger may not be up to the task of keeping a much larger battery up to snuff.

    I rather do see the point of a UPS, just not for me. Since the worst that could happen to me, is perhaps losing a 100 or so tabs of "art" photography. Meh, I'd find them again rather quickly. Or, perhaps losing the current edits on something I have open in Photoshop. There are two forces at work in my case, I'm not much of a "power user", a one of the only "benefits" of living in the awful place I do, is that even 30 inches of snow rarely knocks out the electricity.
    "The best laid plans of men and mice often go astray". That said, suppose you're in the bathroom, the lights aren't on, cause you've got a skylight, and you're reading this month's "PC World magazine" when the power fails. What then.....? :rolleyes:
    1. A well designed PSU will a least bring the ripple well into toleerance With a forced shutdown my more neanderthal recovery approach of F-8 >Safe Mode >> Boot into last known good, works miracles.

      However, with the advent of Windows 7, a forced shutdown brings all the powers of Hell to bear. Windows 7 blasts up a "shame on you dummy warning", then magnanimously offers to repair itself while you of course "wait". And "wait" you do. This is by itself, almost enough of a reason to buy a UPS, so as you don't have to listen to all of Windows s***.
  11. Archean

    Archean TechSpot Paladin Posts: 5,682   +86


    Well XPS provided an control interface for this thing, through which I've set the auto-shutdown in 3 minutes ;)
  12. jobeard

    jobeard TS Ambassador Posts: 9,669   +673

    Yes, but there's that question of "what's left to recover?"

    Scenario: reads are for free (ie no risk at all), but during writes (eg save file or even a paging event) the head typically
    1. seeks to proper cylinder
    2. latency wait for rotation
    3. and then enables write to the block.
    now risk the brown-out during the write

    I've personally seen hardware fail where multiple heads get enabled during this scenario and
    while one block is correctly written, one or more others are clobbered.

    A controlled shudown is much preferred -- especially where there's far more at risk, like business data.

    but then I'm just chicken - - - cluck cluck ;)
  13. captaincranky

    captaincranky TechSpot Addict Posts: 12,017   +2,054

    I quit, you win, that's way more better than my "plan", wherein I would simply place the UPS on a long extension cord, and drag the desktop into the bathroom with me. :rolleyes: :haha: :wave:

    Is this risk as great for single platter drives?

    Although, it pains me to do so. I admit that your probably correct.

    I hope that admission, doesn't mean that we still can't have fun with this topic, does it?
  14. jobeard

    jobeard TS Ambassador Posts: 9,669   +673

    not the object "to win" ;)

    not clear ... what happens if the arm is moved to the parking location and write is still enabled ..
    (we do have a failure so normal timings and controls are ALL suspect imo)

    :wave: :0 ;) :wave:

    imo, the object is to make informed choices with known risk

    best to all our readers
  15. SNGX1275

    SNGX1275 TS Forces Special Posts: 10,715   +397

    I would think (and this is just a guess) that most low cost UPSs use a trickle charger. I know almost all use the 12V Sealed Lead Acid battery types that are something around 3" wide, 4" tall and 6" long, so they can charge pretty quickly even with a .1A charge current. Trickle chargers are also sold for boat batteries to 'keep them topped off' and I think you can actually charge one with it from dead to full if you have a long time (like days-weeks) to wait. So if the battery came with a decent charge in it, the onboard trickle charger on the UPS shouldn't have any issue with keeping it charged, and I don't think it would have any problem charging it back up after the power comes back on, but it might be a very slow process.

    All of this is making the assumption it doesn't have a fancier charger that gets pretty hot while its charging the little battery, but doesn't take long enough to do any damage from the heat. If it gets hot and has to charge for many hours like a marine battery, there might be problems.

    There are quite a few links online about hooking up a car battery to them, and I think even a episode on it. Its just dangerous if you don't have a sealed battery, both for spills, and hydrogen gas buildup if you have it in an enclosed area.

    There is also the fairly real possibility the monitoring software for the amount of time remaining for power won't work if you 'upgrade' the battery, esp if you change types/chemistry.
  16. jobeard

    jobeard TS Ambassador Posts: 9,669   +673

    When I was writing system code, we used redundant controls during exceptional conditions, like getting subprocesses to quit.

    The normal way to stop a process is to send it the SIGTERM condition, so we would write a loop
    while procCnt > 0 {
        SIGTERM $pid; procCnt--;
    On the SIGTERM, the process should give up resources and close files and quit,
    but then not trusting that the process could or would obey, we would do it again using
    while procCnt > 0 {
       SIGKILL $pid; procCnt--;
    which blows the process away regardless and that's the best effort we could do. If the process could not cleanup by the time we went around,
    then it was just hung-up. Did you ever see "Process Not Responding"? Now you know how it gets cleared.

    On SIGTERM, there's never a "mother may I" dialog and the process cleanup is just forced 'cleanly', whereas the SIGKILL is just brutal.

    When the UPS detects the A/C drop, it signals the UPS driver of that fact and the host software trigger is fired;
    wait X minutes, Poff immediately, wait for UPS power reserve to lapse ...

    When the final condition occurs w/o the UPS recovering the A/C, the final shutdown sequence is initiated, very similar to the samples shown above
    followed by System HALT.
  17. montecarlo1987

    montecarlo1987 TS Rookie Topic Starter

    Hello. Thank you for your responses.
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