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Hacking APC UPS's "Master/Controlled" Feature?

Discussion in 'Electronic Repair' started by (PeteCresswell), Oct 30, 2011.

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  1. I just bought two APC ES 750s.

    The feature set touted on the box cites a "Master" outlet that
    controls several "Controlled By Master" outlets.

    My expectation was that the "Controlled" outlets would run on
    battery until the "Master" device shut down.

    The idea is that we can keep the router/switches working while
    the NAS is on backup, but that they will not drain the battery
    once the NAS shuts down.

    Reading other threads, it seems like the "Controlled" outlets are
    not really controlled by the master in the case of power loss:
    they just shut down immediately.

    Direct experience confirms this.

    The Question:

    Has anybody hacked one of these things so they actually function
    as advertised? i.e. when power is lost, the devices connected to
    "Controlled By Master" outlets stay powered up until the device
    connected to the "Master" outlet shuts down.

    My inner electronic/electrical illiterate is hoping that it might
    be a simple as disconnecting a couple of wires in there and
    re-connecting them to a different place.

  2. The specs for this discontinued product state that the five outlets across
    the top are backed up by the battery.

    These outlets will run until the battery voltage drops to where it can no
    longer power the outlets. At that point, those five outlets will all shut
    off. KA-CHOOM!

    IF the device has a "master" outlet (I don't see it in the specs or the
    photos), the "controlled" outlets turn on and off with the master, either
    for convenience, or to save energy. (My audio system is wired this way --
    the electronic crossovers turn the power amps on and off.) Once the battery
    poops out, /everything/ powered by the battery shuts off. There is no
    graceful shutdown.

    You're confusing a convenience feature with operation of the device as a
    source of backup power. The two (apparently) have absolutely nothing to do
    with each other.
  3. Nelson

    Nelson Guest

    Your understanding of how it should work is the same as the user
    Perhaps you have inadvertently disabled it? Did you try pushing the
    button as mentioned?

    You can download a copy of the user guide from the APC site.
  4. Per Nelson:
    The lawyers or some other clever souls added weasel words in the
    User's Guide | 2 Connect Equipment | Master/Controlled Outlets |
    "Note: Do not connect peripherals to the Controlled Outlets if
    you want them to continue to run when your computer is turned

    For the life of my I can't imagine why they would inflict such a
    flawed implementation on their customers. I mean... this is an
    Uninterruptible Power Supply, not a friggin power strip... it's
    all *about* function when the power fails.

    The least they could have done is put that little disclaimer on
    the outside of the box.
  5. Per (PeteCresswell):
    Sorry.... that was a non-sequitur..... I'm so pissed off over
    this that I'm not even thinking clearly any more.

    But, to answer your question, yes - I have the feature enabled.

    It's just that it does not work when the user needs it the most:
    when the power fails.
  6. Nelson

    Nelson Guest

    I don't understand what you want. Do you want the "controlled" outlets
    to continue to have power after the computer shuts down? There are
    other outlets that operate independent of the "master" which do that.
    As I understand it the idea behind the "controlled" outlets is that a
    peripheral which is only used by the computer, eg a printer, doesn't
    need power if the computer is down, so to conserve the remaining
    battery power for the useful items, these are shut down in synchrony
    with the computer.

    I have one of these and it works just fine. There are "uncontrolled"
    outlets which are supplied with power whether the computer is up or
    down, "controlled" outlets which are only supplied with power when the
    computer is up, and surge protected only outlets which are not supplied
    with backup power. I would have chosen the mix between these
    differently, but that is easy enough to get around by plugging power
    strips into one or the other types of outlets.

    In my set up, I have the external hard drives and printer connected to
    the "slave" outlets and the cable modem and VOIP modem connected to the
    "always up" outlets. When the battery is down to 25%, the computer
    shuts itself down along with the peripherals and the modem and router
    continue to provide telephone service. Isn't that the same thing you
  7. Per Nelson:
    I want the "controlled" outlets to be controlled by the "master"
    outlet - at all times, as I think most people would impute from
    what it says on the box the power supply comes in - not just when
    there is external power.

    The reason: if the power goes out, I still want connectivity
    across the LAN, but I don't want the UPS' battery tb drained
    (which shortens it's life).

    Sequence Of Events:
    - Power fails

    - UPS keeps supplying power to PC connected to "Master" and to
    devices connected to "Controlled"

    - UPS sends message to PC telling it that we're on battery backup

    - PC keeps on truckin'.... with LAN connectivity still intact

    - PC's Power Management utility kicks in and, after a preset time
    or a preset remaining battery life, commences a graceful
    shutdown of the PC

    - PC shuts down.

    - UPS then shuts down the router, switches, and whatever else is
    plugged into "Controlled" outlets.

    - The UPS battery does not get totally drained.

    Maybe I'm the only one.... But this seems so obvious that I just
    can't imagine any other implementation in the context of an
    Uninterruptible Power Supply.

    The power-saving thing sounds nice, but I go back to the fact
    that this is an Uninterruptible Power Supply, and not just a
    power strip.
    This may sound like nit picking.... but it's not quite true that
    they are only supplied with power when the computer is up. What's
    true is that they are only supplied with power when the computer
    is up *and* there is external power.
    Where are they getting power, if not from the UPS?
  8. Jerry Peters

    Jerry Peters Guest

    And would you want your laser printer to keep running from the
    battery? The design seem sensible to me.

  9. Nelson

    Nelson Guest

    You're right. I did some plugging and unplugging and checking. If you
    look at the top line of outlets they say "Backup Power + Surge" while
    the bottom line says "Surge Only". The three "Controlled Outlets" are
    on the bottom so I guess that's intended to make it obvious that they
    are surge only (although my initial impression was the same as yours).

    I guess the thinking is that you wouldn't want to be running printers,
    scanners, etc. when you are on backup power as that would shorten the
    amount of time the computer would be able to run. And when you are not
    on backup power, it is convenient to shut off peripherals automatically
    when you shut off the computer. But I agree it is confusing to include
    surge protection only outlets in a UPS.

    Another set of outlets which run on backup power but are controlled by
    the computer would be useful for attached external hard drives, for
    example. That's how I would use them anyway.

    I find it a good little UPS for the money. I bought it to get through
    short duration outages and it does a good job of it. I don't find the
    lack of computer controlled, back up power outlets to be that much of
    an issue, certainly at this price point. Not worth getting upset over
    anyway :)
  10. Per (PeteCresswell):
    Oops.... "uncontrolled" SHB "surge-only"
  11. Per Nelson:
    Agreed - I just have this tendency to go ballistic when I see
    (according to me.... -) especially-egregious violations of
    common sense.

    The thing about avoiding the router/switches draining the UPS
    battery seems to me tb totally basic to the power loss situation.

    I'd been using one of these guys with
    a conventional UPS and I guess I'll try to find a couple more.
  12. Nelson

    Nelson Guest

    So I'm guessing you are going to plug the Belkin into the Master on the
    UPS, the computer into the Master on the Belkin, and the things you
    want to stay up as long as the computer does into the controlled
    outlets on the Belkin.

    You must have really shitty power if you worried about draining the
    battery. My outages are generally not long enough to cause the
    computer to shut down much less discharge the battery completely. I
    doubt if completely discharging the battery once or twice over it's
    lifetime will have much of an impact.

    On a side note, I think obsessing over "standby power" to save the
    planet is absurd in the greater scheme of things. More of a "feel
    good" effect than anything meaningful. And some equipment relies on
    the standby power to maintain its state. For instantce, my external
    speakers reset their volume to zero whenever they are powered down.
  13. Nelson

    Nelson Guest

    I hear ya :) Fooling around with my UPS as a result of this thread
    has reminded me of what a mess all those little transformers are. I
    have a Mac Mini, 6 external Firewire or USB drives, a scanner, a
    printer, a router, a cable modem, a wireless access point, an external
    DVD burner, a cell phone charger, and a telephone. All have different
    geometry transformers which block at least one adjacent socket. I
    bought some 6 inch pigtails that were supposed to fix the problem...
    but the pigtail plugs are so fat that you can't plug _them_ into
    adjacent sockets. And it must be a rule that the plugs on the
    transformers are orthogonal to the slots on the power strip outlets so
    that you end up blocking multiple outlets. Underneath my desk is a
    rat's nest and a fire hazard.

    I have two power strips hanging off the UPS and 6 pigtails just to
    manage to plug everything in... and the result is well under the UPS'
  14. Per Nelson:
    Our outages are rare (as in 1-2x per year max) but when they
    happen they can be a day or two. The one we just had was a
    couple hours short of two days for us, about 4 days for the guys
    across the street.

    Within those outages, of course, are many mini or micro outages
    where some high-startup-current device kicks in and the lights
    dim for long enough to trip a UPS. But in those cases my concerns
    are moot.

    I don't know enough about batteries to have an authoritative
    opinion, but what I've always heard is that total discharge
    damages lead-acid batteries from the get-go. I'm pretty sure
    I've cooked a couple of batteries on my automobiles by totally
    discharging them two or three times. I think that is what's
    behind the special "Deep Cycle" marine batteries: they're
    specially made so that deep or total discharge will not harm them
    as much.

    But, to address what I perceive is the real issue: yes, I might
    be over-thinking this and yes, it's much more theoretical than
    practical.... but that's just my inner obsessive.... -)
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