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Re: [nslu2-linux] Rebooting the Slug after power-outage?

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  • CN
    Fred, If you remove the power connector, and assuming you have a usb hardrive, and supply power thru that one, the slug will auto powerup, at least in unSlung.
    Message 1 of 8 , Aug 1, 2006
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      Fred,

      If you remove the power connector, and assuming you have a usb hardrive, and
      supply power thru that one, the slug will auto powerup, at least in unSlung. But
      now you may not be able to powerdown using the swithches properly. There is
      some discussions on wiki how to do this with some software changes instead.

      Cordially, Chacko

      On Tue, 01 Aug 2006 13:02:06 -0700, Frederic Wenzel wrote:

      > Hey there.
      >
      > I happen to live in a town where the power goes off every once in a
      > while for like one second or so. Bigger computers make it through (big
      > capacitor in the power supply, I figure) but my slug dies.
      >
      > That's unfortunate.
      >
      > I would love to have it automatically reboot after a power outage. Is
      > there a way I can set that up?
      >
      > Thanks
      > Fred
    • CN
      ... I think a capacitor is practical only if the pwr stays off for a fraction of a second, anything past that you would need a huge capacitor. If you put 4 AA
      Message 2 of 8 , Aug 1, 2006
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        On Tue, 01 Aug 2006 22:23:40 +0200, Laurent Gilson wrote:

        > Hello,
        > >
        > > I happen to live in a town where the power goes off every once in a
        > > while for like one second or so. Bigger computers make it through (big
        > > capacitor in the power supply, I figure) but my slug dies.
        >
        > A slug takes like 5w. Get a capacitor for like 30-50 US-cent ...
        >
        > > I would love to have it automatically reboot after a power outage. Is
        > > there a way I can set that up?
        >
        > There is a always-on hack in the wiki (Basicly restarting the slug as soon
        > as the power comes back). But it may fail in your situation if the power
        > comes back too quickly ...
        >
        > cu

        I think a capacitor is practical only if the pwr stays off for a fraction of a second,
        anything past that you would need a huge capacitor.

        If you put 4 AA NiMh rechargeable batteries (about $4 in the USA) in series right
        across the output of your power supply, it will give you as much as 1 hour
        (definitely many minutes ) of operation without any problem. Since at 5 v the
        battery each will be at 1.25 volts, there is no risk of overcharging.

        In this simple arrangement, the battery will never be fully charged, otherwise
        most modern AA batteris (>2300mAHr is very common now) will give almost 1.5 to
        2 hours --- slug takes about 1Amp with a usb 2.5" notebook drive.

        Cordially, Chacko
      • vbgroningen
        ... See this page: http://www.nslu2-linux.org/wiki/HowTo/ForcePowerAlwaysOn I did Alternative 1, and got a free sample from Microchip (very nice of them!).
        Message 3 of 8 , Aug 1, 2006
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          Laurent Gilson wrote:
          > There is a always-on hack in the wiki (Basicly restarting the slug as
          > soon as the power comes back). But it may fail in your situation if
          > the power comes back too quickly ...

          See this page: http://www.nslu2-linux.org/wiki/HowTo/ForcePowerAlwaysOn

          I did Alternative 1, and got a free sample from Microchip (very nice of
          them!). Works well for me.

          PP
        • Frederic Wenzel
          ... That idea is just great. I got the parts and soldered it all together and it works. Now, when I unplug the power, the battery keeps the slug running. I
          Message 4 of 8 , Aug 5, 2006
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            CN schrieb:
            >> There is a always-on hack in the wiki (Basicly restarting the slug as
            > soon
            >> as the power comes back). But it may fail in your situation if the power
            >> comes back too quickly ...
            >>
            >
            > I think a capacitor is practical only if the pwr stays off for a
            > fraction of a second,
            > anything past that you would need a huge capacitor.
            >
            > If you put 4 AA NiMh rechargeable batteries (about $4 in the USA) in
            > series right
            > across the output of your power supply, it will give you as much as 1 hour
            > (definitely many minutes ) of operation without any problem. Since at 5
            > v the
            > battery each will be at 1.25 volts, there is no risk of overcharging.

            That idea is just great. I got the parts and soldered it all together
            and it works. Now, when I unplug the power, the battery keeps the slug
            running. I still have to run a longer test (to see if the batteries
            don't explode ;) or discharge altogether or whatever) but for now it
            works just great.

            Including wire (which was only available as 35 ft. or more), it cost me
            25 bucks now at Radioshack.

            I will blog and wikify that soon (giving you credit for the initial idea :))

            Fred
          • CN
            ... I am reasonably sure the batteries will not overcharge. When they are discharged they have under 1.2 v each (4.8v), and when they are fully charged, they
            Message 5 of 8 , Aug 5, 2006
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              On Sat, 05 Aug 2006 13:57:19 -0700, Frederic Wenzel wrote:

              > CN schrieb:
              > >> There is a always-on hack in the wiki (Basicly restarting the slug as
              > > soon
              > >> as the power comes back). But it may fail in your situation if the power
              > >> comes back too quickly ...
              > >>
              > >
              > > I think a capacitor is practical only if the pwr stays off for a
              > > fraction of a second,
              > > anything past that you would need a huge capacitor.
              > >
              > > If you put 4 AA NiMh rechargeable batteries (about $4 in the USA) in
              > > series right
              > > across the output of your power supply, it will give you as much as 1 hour
              > > (definitely many minutes ) of operation without any problem. Since at 5
              > > v the
              > > battery each will be at 1.25 volts, there is no risk of overcharging.
              >
              > That idea is just great. I got the parts and soldered it all together
              > and it works. Now, when I unplug the power, the battery keeps the slug
              > running. I still have to run a longer test (to see if the batteries
              > don't explode ;) or discharge altogether or whatever) but for now it
              > works just great.
              >
              > Including wire (which was only available as 35 ft. or more), it cost me
              > 25 bucks now at Radioshack.
              >
              > I will blog and wikify that soon (giving you credit for the initial idea :))
              >
              > Fred

              I am reasonably sure the batteries will not overcharge. When they are
              discharged they have under 1.2 v each (4.8v), and when they are fully
              charged, they go to about 1.4 (5.6v). So with the slug power supply at 5.0 or
              very close to it, the bateeries will stop charging at some point in between (the
              voltage vs charge curve is not quite linear). The only downside I see is that
              the batteries will always be only charged to about 30% or so in your normal
              'floating' operation, but even that should provide 10s of minutes of backup.

              As for the cost, 4AA nimh batteries are routinely available for about $5 or less
              on ebay...

              This will have another significant advantage if you are running two usb
              harddrives solely powered off the slug. My observation is that the powersupply
              just does not have enough transient capacity for two drives (when the motor
              starts, or the head moves). But a battery float like this will make the two
              drives operation quite reliable --- this is a conjecture at this point, I have not
              tried this yet, but is planning to do this. In normal idle times in between
              reading or writing, there is enough extra current available form the slug charger
              to keep the battery get the lost charge during the transient heavy loads.

              Keep us posted about your experiences...

              Cordially, Chacko
            • Frederic Wenzel
              ... True, that sounds reasonable. I am done blogging it: http://en.magenson.de/2006/08/05/linksys-nslu2-battery-ups/ Guess I should donate the text to the
              Message 6 of 8 , Aug 5, 2006
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                CN schrieb:
                > I am reasonably sure the batteries will not overcharge. When they are
                > discharged they have under 1.2 v each (4.8v), and when they are fully
                > charged, they go to about 1.4 (5.6v). So with the slug power supply at
                > 5.0 or
                > very close to it, the bateeries will stop charging at some point in
                > between (the
                > voltage vs charge curve is not quite linear).

                True, that sounds reasonable.

                I am done blogging it:
                http://en.magenson.de/2006/08/05/linksys-nslu2-battery-ups/

                Guess I should donate the text to the wiki, too, hm?


                Fred
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