Planning on buying a battery backup; could use some advice

Discussion in 'Buying Tips and Advice' started by bpetruzzo, Jun 10, 2009.

  1. bpetruzzo macrumors regular

    Oct 22, 2005
    Planning on buying a battery backup for my MacBook Pro, four external drives and 28" monitor. Obviously the notebook doesn't need the backup, I'm more concerned about power failure on the drives and screen. I figured that I wouldn't need a very big one, but I really am not sure how to decide. I just need it to buy me enough time to do a soft shut down on the hardware.

    Any help would really be appreciated.
  2. old-wiz macrumors G3

    Mar 26, 2008
    West Suburban Boston Ma
    I think the monitor would be too much for the UPS. The UPS devices tell you how much power they can provide for how long a time. Unfortunately I don't remember the figures.
  3. bpetruzzo thread starter macrumors regular

    Oct 22, 2005
    I just can't figure out how to add it all up. But I could pretty easily bypass the monitor if I need to. It is a notebook, so if the power cuts, I'll just shut everything down with the built in display.

    I'm just not sure how to figure out how big a ups I'd need.
  4. m85476585 macrumors 65816

    Feb 26, 2008
    I can't think of any reason to put the monitor on a UPS. If the power goes out for more than a few seconds, go back to the built-in LCD, save your work, and unmount the drives.

    External drives would really benefit from a UPS, but make sure they can stay on long enough for it to switch over to battery. Regular UPSes take a few milliseconds after the power goes out to switch over to battery power. There are "online" UPSes that have no delay, but they are very expensive.

    I recently experienced very bad corruption of a drive when the power flickered while I was working on it. The computer (a Desktop with no UPS) stayed on, the monitor (a CRT) flickered a little, but the drive cycled completely off and back on. the corruption was so bad that Windows crashed trying to format the drive, and my mac wouldn't mount it. I had to download the manufacturer's low level format utility, which restored the drive to a usable state. I don't know if a UPS would have switched fast enough to keep the drive on during the brief power failure. I might add some big capacitors to the drive's external power supply to make its own mini online UPS to give it time for a regular UPS to kick in. Of course, I don't have a UPS yet, so I can't test if the switching time is fast enough.
  5. bpetruzzo thread starter macrumors regular

    Oct 22, 2005
    I suspect that it's probably okay. The power has flickered before without the drives going off. Although, I guess there's no real way to know, right?
  6. m85476585 macrumors 65816

    Feb 26, 2008
    The only way to know for sure if a UPS is fast enough for your drives is to test it. When the UPS is charged, unplug it from the wall and see what happens. If the drive(s) stay on, you are probably fine. If they click off then spin back up, you have a problem.

    You could always make your own online UPS (though I don't really recommend it). You need a large deep cycle battery, an inverter big enough to handle everything that you might have plugged in, and a charger for the battery that can also supply enough power to charge the battery and power anything you might have connected to it at the same time. Hook up the inverter and the charger to the battery, turn both of them on, and you should be all set. I don't recommend it because most battery chargers are not designed to charge a battery and run an inverter at the same time. They usually have 2-4 distinct modes (constant current, constant voltage, trickle charge, etc) that might or might not be able to power the inverter, and the mode detection circuitry might be confused by the extra load. Also, cheaper inverters put out noisy power (modified sine wave) that might not be suitable for some devices and will cause your magsafe adapter to get very warm.
  7. dukeman macrumors member

    Feb 5, 2007
    If the monitor is an LCD you should be fine with around a 500VA unit. You would probably get 20-30 mins of run time.

    My MacPro at home with external drive sits on a tripplite 1500 and I haven't had any issues with the external drive when it clicks over, which it does very frequently.

    On a side note an APC 1500 runs my 36" CRT TV / DVR in my living room for a good 30-40 mins. Its fun to watch TV in a blackout :)
  8. bpetruzzo thread starter macrumors regular

    Oct 22, 2005
    As it turns out, I happened upon a UPS on clearance at a local Radio Shack for $20 (like, 85% off or something). It's 600VA, 300w. I have four external drives plugged into it and I have the monitor and notebook on the surge protector side. A quick test with one of the drives earlier tonight was successful. But I'll have to check it again once it's fully charged to see how it likes all four of them.

Share This Page