UPS Power: Pure Sinewave or Stepped?

Discussion in 'iMac' started by Bryan Bowler, Aug 16, 2010.

  1. Bryan Bowler macrumors 68040

    Sep 27, 2008
    I am getting ready to purchase an UPS for my 27" i7 iMac. After a considerable amount of research using mRoogle and Google, I'm still left with a decision to make. Perhaps the experts here can help me decide.

    For my personal needs, all I need is enough power to save my work and perform a graceful shutdown. I found the models with the right wattage that will suit this need. Check.

    The real problem lies in the power that is supplied once the battery kicks in. Cheaper models, such as the APC BackUPS ES 750G ($84.99 on Amazon) provide a "stepped approximation to a sinewave". Some folks claim that the iMac power supply doesn't care for this type of input as it is not as efficient as a pure sinewave that is delivered every day by the power company. As a result, some people recommend getting a Smart-UPS, which provides a pure sinewave when the battery power kicks in. A Smart-UPS will also condition the regular everyday power ensuring that your computer always has clean power, whether it's coming from the power company or the battery. The problem is the cost. A Smart-UPS costs $350-$500 new or $200 +/- for a refurbished model.

    As mentioned above, I don't have a need to run my computer for an extended period on battery power. I just need to save my work and power down. If my computer is asleep, then the UPS will simply power it down. So I'm thinking that I can get away with the cheaper option and that it's no big deal if my iMac runs on a "stepped approximation to a sinewave" for the 2 minutes (or so) that it takes to power down. But then again, I'm not sure.

    I would appreciate opinions from everyone in the crowd. Extensive searches have left me scratching my head.

  2. Argon21 macrumors member

    Jun 25, 2010
    Алейск, RUSSIA
    I recommend not buying APC. I know I'll never buy any of their products again. They set their float voltage too high which cooks the battery in about 3 years. A sealed gel cell battery should last 6+ years, which it does in other manufacturers products. Also they have shitey inverters that overheat easily. I prefer Tripp Lite myself, they make a better quality product IMO and also sell higher end Medical grade devices. APC is like Monster Cable... over priced junk.

    As for square vs. sine, I say go for Sine. I paid a few bucks more for Sine after testing them both. Square wave made some hideous noise from any powered speakers or audio amplifiers I had plugged in. Plus I've heard it does bad things to certain types of power supplies.

    Also consider that there are all different UPS architectures. The cheapo ones are just pass-thru for the power, until it goes out, and then inverter and battery take over. Better ones perform line conditioning on the power instead of just pass through. The best ones run the inverter at 100% duty cycle, so you're always running off it, but those are more for medical use and server rooms rather than personal home usage.
  3. Bryan Bowler thread starter macrumors 68040

    Sep 27, 2008
    Thanks for the input. I guess the real question is, at least in my mind, does it really matter if the iMac gets a stepped approximation to a sinewave for 2 minutes when it switches over to battery power? Sure, it's not a pure sinewave, but most casual users just need enough time for a graceful shutdown.

    Is it really a big deal for a few minutes?

  4. Btom macrumors 6502a

    Nov 19, 2009
    Grid power can be very dirty (I mean it in a good sense) with a lot of garbage (noise) on it, short outages and phase jumps and we don't hear about electronic things blowing up around. Most likely there is no problem, but is the Amazon model specified as a computer grade (to be able to blame somebody)?

    Tom B.
  5. mindquest macrumors regular

    Oct 25, 2009
    Which model Tripp Lite do you like?
  6. rworne macrumors 6502a

    Jul 23, 2002
    Tell that to my collection of TrippLite OmniLCD 1000 units. Worked great for a couple of years, now they suffer from random shutdowns - precisely what they are supposed to prevent. 2 out of three failed with the same issue and complaints about them can be found on the 'net. The APC 1500 from 2006 is still running strong (thank you Staples for closing them out for $60 :) ).

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