• Backup power supply

    From Andriy D@3:770/3 to All on Wed Mar 13 13:18:44 2024
    Hi,

    I'm considering adding some backup power supply for my RPi2 mainly
    to avoid filesystem issues which may be caused by a short power outage.
    There are some interesting schematics online as well as some quite
    cheap 'manufactured' options. But I'm wondering, maybe someone has
    some experience / feedback to share?

    Cheers,

    \aID

    --- SoupGate-Win32 v1.05
    * Origin: Agency HUB, Dunedin - New Zealand | Fido<>Usenet Gateway (3:770/3)
  • From Mike Scott@3:770/3 to Andriy D on Wed Mar 13 14:41:04 2024
    On 13/03/2024 13:18, Andriy D wrote:
    Hi,

    I'm considering adding some backup power supply for my RPi2 mainly
    to avoid filesystem issues which may be caused by a short power outage. There are some interesting schematics online as well as some quite
    cheap 'manufactured' options. But I'm wondering, maybe someone has
    some experience / feedback to share?


    No answers - but it's something I've been wondering about off and on
    (albeit for a Pi4). All the commercial stuff I've seen much exceeds the
    base Pi in either £££ or W (or both).

    Any offers out there? Even something with a stack of AA
    non-rechargeables would be fine.

    --
    Mike Scott
    Harlow, England

    --- SoupGate-Win32 v1.05
    * Origin: Agency HUB, Dunedin - New Zealand | Fido<>Usenet Gateway (3:770/3)
  • From Vincent Coen@2:250/1 to Andriy D on Wed Mar 13 16:32:32 2024
    Hello Andriy!

    Wednesday March 13 2024 13:18, you wrote to All:

    Hi,

    I'm considering adding some backup power supply for my RPi2 mainly
    to avoid filesystem issues which may be caused by a short power
    outage. There are some interesting schematics online as well as some
    quite cheap 'manufactured' options. But I'm wondering, maybe someone
    has some experience / feedback to share?

    There are some battery powered sub systems/ card available but you are limited by the capacity of them which is not that great. For all important computer systems I use APC smart UPS's connect to a large adaptor block that hold around
    9 sockets with the APC unit being 1000Va. I did have a 2k2 VA but the batteries along with the main board failed and APC do not have spares so switch
    since then to 1000va units for my and my wife's requirements. The batteries last around 5 - years before replacement and I have found 3rd party sources for
    the batteries for around 30 pounds instead of the 100 or so for the same thing but with APC branding. It takes less than 5 minutes to swap over and you can keep the UPS running while doing it.

    Note that printers are not connected the the UPS but router and primary hubs are. I did for a while also have a Pi3B+ (plus Hard drive) also connected to it when running 24/7 but switched the jobs over to my main system and discontinued the Pi despite late last year buying at great effort a Pi4B 8Gb, 240 Gb SSD all in a Argon 40 case to act as a back up but never used it - must remember to sell in on Ebay.

    Vincent

    --- Mageia Linux v8 X64/Mbse v1.0.8.5/GoldED+/LNX 1.1.5-b20180707
    * Origin: Air Applewood, The Linux Gateway to the UK & Eire (2:250/1)
  • From Andriy D@3:770/3 to Mike Scott on Wed Mar 13 16:39:58 2024
    Mike Scott <usenet.16@scottsonline.org.uk.invalid> wrote:
    On 13/03/2024 13:18, Andriy D wrote:
    Hi,

    I'm considering adding some backup power supply for my RPi2 mainly
    to avoid filesystem issues which may be caused by a short power outage.
    ...

    Any offers out there? Even something with a stack of AA
    non-rechargeables would be fine.


    There are tons of different '5v usb ups' options on Aliexpress :)
    But if you've ever dealt with them, you know the quality ...

    I'm inclining towards DIY as I've found quite developed
    schematics online - with a charge control, signaling loop to RPi, auto-restart, etc.
    But wanted to check what others did, before diving into 'PCB ordering and resistors procurement' deeps :)

    --

    Cheers,
    \aID

    --- SoupGate-Win32 v1.05
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  • From Richard Falken@1:135/115 to Andriy D on Wed Mar 13 13:19:46 2024
    Re: Backup power supply
    By: Andriy D to All on Wed Mar 13 2024 01:18 pm

    Hi,

    I'm considering adding some backup power supply for my RPi2 mainly
    to avoid filesystem issues which may be caused by a short power outage. There are some interesting schematics online as well as some quite
    cheap 'manufactured' options. But I'm wondering, maybe someone has
    some experience / feedback to share?

    Cheers,

    \aID

    --- SoupGate-Win32 v1.05
    * Origin: Agency HUB, Dunedin - New Zealand | Fido<>Usenet Gateway (3:770/3

    Any inexpensive backup power unit from a recognized brand will do. There is no need to overthinkig it if you don't want to. The cool thing of an Uninterrupted Power Supply from a recognized manufacturer is you can get one the RPi can talk to over USB (or whatever), so the RPi will be aware of the stat of the battery and shutdown if it gets dangerously low.

    Production servers hooked to complex power systems are able to send you an email to your smartphone if power goes out, or if battery gets dangerously low etc. because of this reason.

    Building one yourself? I have never done it but it looks quite doable. Keep in mind that starting an electrical fire or spilling the contents of your homemade battery on your carpet sucks. I'd use a self-made unit for the fun of it in a safe environment but I would not leave it running 24/7 so happily.

    --
    gopher://gopher.richardfalken.com/1/richardfalken
    --- SBBSecho 3.20-Linux
    * Origin: Palantir * palantirbbs.ddns.net * Pensacola, FL * (1:135/115)
  • From Mike Scott@3:770/3 to Vincent Coen on Wed Mar 13 18:47:00 2024
    On 13/03/2024 03:32, Vincent Coen wrote:
    systems I use APC smart UPS's connect to a large adaptor block that hold around
    9 sockets with the APC unit being 1000Va. I did have a 2k2 VA but the

    And what's the standby current of such a UPS?

    --
    Mike Scott
    Harlow, England

    --- SoupGate-Win32 v1.05
    * Origin: Agency HUB, Dunedin - New Zealand | Fido<>Usenet Gateway (3:770/3)
  • From Mike Scott@3:770/3 to Andriy D on Wed Mar 13 18:58:30 2024
    On 13/03/2024 16:39, Andriy D wrote:
    There are tons of different '5v usb ups' options on Aliexpress πŸ™‚
    But if you've ever dealt with them, you know the quality ...

    :-}


    --
    Mike Scott
    Harlow, England

    --- SoupGate-Win32 v1.05
    * Origin: Agency HUB, Dunedin - New Zealand | Fido<>Usenet Gateway (3:770/3)
  • From bp@www.zefox.net@3:770/3 to Mike Scott on Wed Mar 13 23:14:56 2024
    Mike Scott <usenet.16@scottsonline.org.uk.invalid> wrote:
    On 13/03/2024 13:18, Andriy D wrote:
    Hi,

    I'm considering adding some backup power supply for my RPi2 mainly

    No answers - but it's something I've been wondering about off and on
    (albeit for a Pi4). All the commercial stuff I've seen much exceeds the
    base Pi in either pounds [Sterling] or W (or both).

    Any offers out there? Even something with a stack of AA
    non-rechargeables would be fine.

    For one Pi a 5 volt regulator connected to a battery
    that's held on a float charger is probably the cheapest,
    though I think the combo will cost more than any Pi. The
    efficiency of such a setup is poor, but for one Pi it's
    probably better than a more elaborate scheme. Also, there
    is no need for line detection logic, which can be tricky.

    For my part I settled on a small inverter/charger connected
    to a 12 volt battery. It's even more expensive, but has extra
    capacity to run all of my computer and network equipment.
    Cost at the time was about $600, more than half of it the
    lithium iron phosphate battery. A bit cheaper now.

    Rated output is 800 W 120 VAC 60 Hz. The battery can deliver
    about half that power for about an hour, or run my equipment
    overnight. Standby loss is about 10 watts.

    HTH,

    bob prohaska

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  • From Andriy D@3:770/3 to Richard Falken on Thu Mar 14 07:57:02 2024
    Richard Falken <nospam.Richard.Falken@f1.n770.z14837.fidonet.org> wrote:

    I'm considering adding some backup power supply for my RPi2 mainly
    to avoid filesystem issues which may be caused by a short power outage. There are some interesting schematics online as well as some quite
    cheap 'manufactured' options. But I'm wondering, maybe someone has
    some experience / feedback to share?

    Any inexpensive backup power unit from a recognized brand will do. There is no
    need to overthinkig it if you don't want to. The cool thing of an Uninterrupted
    You mean full blown AC UPS, like APC used to do? Or do you know some well-known brands producing USB UPS?

    Building one yourself? I have never done it but it looks quite doable. Keep in
    mind that starting an electrical fire or spilling the contents of your homemade
    battery on your carpet sucks. I'd use a self-made unit for the fun of it in a safe environment but I would not leave it running 24/7 so happily.
    This is exactly my concern - I want this think up&running 24/7/365 and I don't want
    it to burn my house down :)
    I guess this is where you'd say 'risk' and 'price' are in a inverse relationship ;)


    --

    Cheers,
    \aID

    --- SoupGate-Win32 v1.05
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  • From The Natural Philosopher@3:770/3 to Andriy D on Thu Mar 14 09:17:20 2024
    On 14/03/2024 07:57, Andriy D wrote:
    This is exactly my concern - I want this think up&running 24/7/365 and I don't want
    it to burn my house down πŸ™‚
    I guess this is where you'd say 'risk' and 'price' are in a inverse relationship πŸ˜‰


    --
    It is entirely possible to trickle charge a lithium cell at uber low
    risk, Essentially you want to current limit the supply at at one tenth
    of the hourly capacity so e,g a 2200mAh celll would need to be charged
    at no more than 220mA, and voltage limit the charge at 4.2V.

    That will give you a cell which, off charge in UPS mode will slowly
    decay to an end point of around 3.5V.
    You will need a step up converter to deliver a sane 5V to the pi and
    some way to power it all down in case of battery going too low.

    That's probably a case for a Pi Pico.
    Or buy a unit that's already done it all :-)


    --
    Those who want slavery should have the grace to name it by its proper
    name. They must face the full meaning of that which they are advocating
    or condoning; the full, exact, specific meaning of collectivism, of its
    logical implications, of the principles upon which it is based, and of
    the ultimate consequences to which these principles will lead. They must
    face it, then decide whether this is what they want or not.

    Ayn Rand.

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  • From Joe@3:770/3 to Andriy D on Thu Mar 14 15:51:28 2024
    I'm using a cheap APC, I believe 650 or 750, with USB monitoring hookup. Also have my router connected (with VOIP) to keep
    communication possible for a little while (runtime abt 30 minutes). Battery replaced once, I believe it was some 7 years old.


    On Wed, 13 Mar 2024 13:18:45 -0000 (UTC), usenet@dolik.dev (Andriy D) wrote:

    Hi,

    I'm considering adding some backup power supply for my RPi2 mainly
    to avoid filesystem issues which may be caused by a short power outage. >There are some interesting schematics online as well as some quite
    cheap 'manufactured' options. But I'm wondering, maybe someone has
    some experience / feedback to share?

    Cheers,

    \aID

    --- SoupGate-Win32 v1.05
    * Origin: Agency HUB, Dunedin - New Zealand | Fido<>Usenet Gateway (3:770/3)
  • From Mike Scott@3:770/3 to Joe on Thu Mar 14 16:32:00 2024
    On 14/03/2024 15:51, Joe wrote:
    I'm using a cheap APC, I believe 650 or 750, with USB monitoring hookup. Also have my router connected (with VOIP) to keep
    communication possible for a little while (runtime abt 30 minutes). Battery replaced once, I believe it was some 7 years old.

    Somehow that makes no sense to me..... current 650 is Β£227 (maybe plus
    VAT) on the APC website. 5 times the cost of the Pi. I'm sure it's a
    very nice UPS, but.... ???





    On Wed, 13 Mar 2024 13:18:45 -0000 (UTC), usenet@dolik.dev (Andriy D) wrote:

    Hi,

    I'm considering adding some backup power supply for my RPi2 mainly
    to avoid filesystem issues which may be caused by a short power outage.
    There are some interesting schematics online as well as some quite
    cheap 'manufactured' options. But I'm wondering, maybe someone has
    some experience / feedback to share?

    Cheers,

    \aID

    --
    Mike Scott
    Harlow, England

    --- SoupGate-Win32 v1.05
    * Origin: Agency HUB, Dunedin - New Zealand | Fido<>Usenet Gateway (3:770/3)
  • From bp@www.zefox.net@3:770/3 to Mike Scott on Thu Mar 14 18:11:24 2024
    Mike Scott <usenet.16@scottsonline.org.uk.invalid> wrote:
    On 14/03/2024 15:51, Joe wrote:
    I'm using a cheap APC, I believe 650 or 750, with USB monitoring hookup. Also have my router connected (with VOIP) to keep
    communication possible for a little while (runtime abt 30 minutes). Battery replaced once, I believe it was some 7 years old.

    Somehow that makes no sense to me..... current 650 is 227 pounds (maybe plus VAT) on the APC website. 5 times the cost of the Pi. I'm sure it's a
    very nice UPS, but.... ???


    Sense or not, it seems to be a fact of life. The inverter/charger/transfer units
    I used have vanished from Amazon, replace by units with four times the power and
    double the price. Battery prices seem to have dropped very slightly, but are still a whisker over $200/kWH.

    A 12 volt to 5 volt stepdown converter appears to be less than $10, small 12 volt
    batteries range from $20-100 in the few AH range, a 12 volt 5 amp charger ranges
    from $11 to $50. The charger would be the iffy part, since a smart charger on a loaded battery is apt to get confused by what looks like high self-discharge..

    Something reliable for less than $100 will take both luck and ingenuity. One possibility is finding a used UPS unit in e-waste and replacing the battery.

    bob prohaska






    On Wed, 13 Mar 2024 13:18:45 -0000 (UTC), usenet@dolik.dev (Andriy D) wrote: >>
    Hi,

    I'm considering adding some backup power supply for my RPi2 mainly
    to avoid filesystem issues which may be caused by a short power outage. >>> There are some interesting schematics online as well as some quite
    cheap 'manufactured' options. But I'm wondering, maybe someone has
    some experience / feedback to share?

    Cheers,

    \aID


    --- SoupGate-Win32 v1.05
    * Origin: Agency HUB, Dunedin - New Zealand | Fido<>Usenet Gateway (3:770/3)
  • From Vincent Coen@2:250/1 to Mike Scott on Thu Mar 14 21:00:48 2024
    Hello Mike!

    Wednesday March 13 2024 18:47, you wrote to me:

    On 13/03/2024 03:32, Vincent Coen wrote:
    systems I use APC smart UPS's connect to a large adaptor block that
    hold around 9 sockets with the APC unit being 1000Va. I did have a
    2k2 VA but the

    And what's the standby current of such a UPS?

    Standby ?

    Assuming it is fully charged which would be normal (assuming no outage in the preceding 2 - 3 hours 95% or better.

    Otherwise do you mean the estimated run time if so then system under power in watts per
    hour under the rated size - 25% so lets say :

    750 w
    ---- = 150 = long time :)
    5 w


    Also e.g., my desktop / server system with an estimated consumption of 250w (and it is lower as using modular PSU, 85% eff or better ) would be around 3 hours but that assumes there is nothing else under load and there is such as:: Router
    Baby Hub
    Monitor ( but only when I am using it )
    Telephone systems including VOIP adaptor
    Residual loading - not known as no means to test it.

    Total time with a 25% battery remaining around 90 minutes allowing for 7 minutes to shut down and battery remaining of around 22-23 % approx.

    If I am present when power goes I can shutdown the monitor and let it does its thing if battery drops to predetermined amount of 25%.
    That said during the cold months (UK wise) and I am around I will manually shutdown after 15 minutes and transfer the UPS o/p to the C.H. and turn it on in which case over 24 hours runtime, but so far has never got any where near it
    before power is restored. My old house in a village power outs could be longer and hence the reason for 2 x 2.2Kva UPS's. ( Also smart models ).

    Gave me enough time to power up my ex-mil generator if needed but it was a petrol model so did go through it - petrol I mean so had to keep a few jerry cans filled with fresh fuel as a JIC.


    Vincent

    --- Mageia Linux v8 X64/Mbse v1.0.8.5/GoldED+/LNX 1.1.5-b20180707
    * Origin: Air Applewood, The Linux Gateway to the UK & Eire (2:250/1)
  • From Computer Nerd Kev@3:770/3 to Andriy D on Fri Mar 15 07:45:32 2024
    Andriy D <usenet@dolik.dev> wrote:
    The Natural Philosopher <tnp@invalid.invalid> wrote:
    On 14/03/2024 07:57, Andriy D wrote:
    This is exactly my concern - I want this think up&running 24/7/365 and I don't want
    it to burn my house down :)
    I guess this is where you'd say 'risk' and 'price' are in a inverse relationship ;)
    --
    It is entirely possible to trickle charge a lithium cell at uber low
    risk, Essentially you want to current limit the supply at at one tenth
    of the hourly capacity so e,g a 2200mAh celll would need to be charged
    at no more than 220mA, and voltage limit the charge at 4.2V.
    Majority of the schemes I've found so far suggest use of NiMH cells as
    they are less 'combustive'.

    Indeed, but if the power requirements are low (a Pi Zero without any power-hungry USB/HDMI connections) then supercaps might be an easier
    option. Since then you don't need to worry about over-charging,
    which will still wear out NiMH, even if it doesn't then burn your
    house down.

    Here's one project that came up in a quick search: https://hackaday.com/2020/11/05/a-super-ups-for-the-pi/

    However cheap AliExpress devices do use Li-ion cells. Confusing :)

    Confusing? Not at all, those Chinese sellers know you're not going
    to be able to sue them if their junk burns your house down. If you
    buy a mains powered device from them I think you're lucky if the
    secondary doesn't short right through to the mains and kill you
    when you touch it - it's happened before with phone chargers. It
    was recently in the news here in Aus that Li-Ion batteries had
    caused over 1,000 fires in the past year. I'm highly suspicious
    even of cheap locally-distributed Li-Ion products and wouldn't
    consider buying one from an unaccountable AliExpress seller unless
    I was prepared to sit near it the whole time it charges on a
    fire-proof surface.

    --
    __ __
    #_ < |\| |< _#

    --- SoupGate-Win32 v1.05
    * Origin: Agency HUB, Dunedin - New Zealand | Fido<>Usenet Gateway (3:770/3)
  • From Andriy D@3:770/3 to Computer Nerd Kev on Fri Mar 15 08:45:46 2024
    Computer Nerd Kev <not@telling.you.invalid> wrote:
    Andriy D <usenet@dolik.dev> wrote:
    The Natural Philosopher <tnp@invalid.invalid> wrote:
    On 14/03/2024 07:57, Andriy D wrote:
    This is exactly my concern - I want this think up&running 24/7/365 and I don't want
    it to burn my house down :)
    I guess this is where you'd say 'risk' and 'price' are in a inverse relationship ;)
    --
    It is entirely possible to trickle charge a lithium cell at uber low
    risk, Essentially you want to current limit the supply at at one tenth
    of the hourly capacity so e,g a 2200mAh celll would need to be charged
    at no more than 220mA, and voltage limit the charge at 4.2V.
    Majority of the schemes I've found so far suggest use of NiMH cells as
    they are less 'combustive'.

    Indeed, but if the power requirements are low (a Pi Zero without any power-hungry USB/HDMI connections) then supercaps might be an easier
    option. Since then you don't need to worry about over-charging,
    which will still wear out NiMH, even if it doesn't then burn your
    house down.
    I had this thought as well, as all I need is to have enough power to
    cover for a few seconds of a power outage or gracefully shutdown RPi if
    it's longer than that. Thanks for that link!

    --

    Cheers,
    \aID

    --- SoupGate-Win32 v1.05
    * Origin: Agency HUB, Dunedin - New Zealand | Fido<>Usenet Gateway (3:770/3)
  • From Andy Burns@3:770/3 to Vincent Coen on Fri Mar 15 09:40:16 2024
    Vincent Coen wrote:

    Mike Scott wrote:

    And what's the standby current of such a UPS?

    Standby ?

    Assuming it is fully charged which would be normal (assuming no outage in the preceding 2 - 3 hours 95% or better.

    Otherwise do you mean the estimated run time if so then system under power in watts per
    hour under the rated size - 25% so lets say :

    750 w
    ---- = 150 = long time :)
    5 w

    I think he means what's the vampire load of just keeping a UPS warm :-)

    --- SoupGate-Win32 v1.05
    * Origin: Agency HUB, Dunedin - New Zealand | Fido<>Usenet Gateway (3:770/3)
  • From Ahem A Rivet's Shot@3:770/3 to Vincent Coen on Fri Mar 15 10:51:40 2024
    On Thu, 14 Mar 2024 21:00:49 +1300
    nospam.Vincent.Coen@f1.n250.z2.fidonet.org (Vincent Coen) wrote:

    Assuming it is fully charged which would be normal (assuming no outage in
    the preceding 2 - 3 hours 95% or better.

    Otherwise do you mean the estimated run time if so then system under
    power in watts per
    hour

    You have units confusion. Watt is a unit of power, a rate of
    movement of energy. Watt-Hours and similar units are units of energy. Watts
    per hour is meaningless.

    under the rated size - 25% so lets say :

    Assuming you are talking about an APC SMT750I or similar they are
    rated for a power output of 750VA or 500W. At full power the battery is
    good for about five minutes.

    750 w
    ---- = 150 = long time :)
    5 w

    Make that 5 minutes * 500W/5W or 500 minutes which is indeed a long time but a lot shorter than the 150 hours you were expecting.

    Also e.g., my desktop / server system with an estimated consumption of
    250w (and it is lower as using modular PSU, 85% eff or better ) would be around 3 hours but that assumes there is nothing else under load and

    No it would be maybe 15 minutes.

    --
    Steve O'Hara-Smith
    Odds and Ends at http://www.sohara.org/
    For forms of government let fools contest
    Whate're is best administered is best - Alexander Pope

    --- SoupGate-Win32 v1.05
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  • From Joe@3:770/3 to Mike Scott on Fri Mar 15 12:55:24 2024
    On Thu, 14 Mar 2024 16:32:01 +0000, Mike Scott <usenet.16@scottsonline.org.uk.invalid> wrote:

    On 14/03/2024 15:51, Joe wrote:
    I'm using a cheap APC, I believe 650 or 750, with USB monitoring hookup. Also have my router connected (with VOIP) to keep
    communication possible for a little while (runtime abt 30 minutes). Battery replaced once, I believe it was some 7 years old.

    Somehow that makes no sense to me..... current 650 is £227 (maybe plus
    VAT) on the APC website. 5 times the cost of the Pi. I'm sure it's a
    very nice UPS, but.... ???

    It's a APC Back-UPS ES 8 Outlet 700VA 230V, paid 70 eur for it (clearance sale). Replacement battery was 54 eur. Like mentioned
    it's NOT just for the Pi but also for the fiber router/VOIP as cell phone is unreliable here.

    Since then for other purposes I've also got an Eaton Ellipse ECO 1600 @ 184 eur (Amazon daily sale).

    SO I guess looking around for reasonable prices may make sense....

    This one https://www.amazon.co.uk/Eaton-850B-UPS-Uninterruptible-Type-Black-white/dp/B0B3RQN8QT @ (today) 126 UKP is similar to the
    APC, includes shutdown & monitoring via USB + software. I trust Eaton as much (or more) as APC.

    --- SoupGate-Win32 v1.05
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  • From Andriy D@3:770/3 to Joe on Fri Mar 15 13:28:28 2024
    Joe <none@nowhere.whereo> wrote:

    I'm using a cheap APC, I believe 650 or 750, with USB monitoring
    hookup. Also have my router connected (with VOIP) to keep
    communication possible for a little while (runtime abt 30 minutes).
    Battery replaced once, I believe it was some 7 years old.

    Somehow that makes no sense to me..... current 650 is 227 (maybe plus
    VAT) on the APC website. 5 times the cost of the Pi. I'm sure it's a
    very nice UPS, but.... ???
    ...

    This one https://www.amazon.co.uk/Eaton-850B-UPS-Uninterruptible-Type -Black-white/dp/B0B3RQN8QT
    @ (today) 126 UKP is similar to the
    APC, includes shutdown & monitoring via USB + software. I trust Eaton
    as much (or more) as APC.
    Speaking of Eaton, I've found they have Eaton 3S Mini UPS which seems to
    be good a match for my original purpose. And price of around 50 eur makes
    it a cheapest brand-name option so far :)

    --

    Cheers,
    \aID

    --- SoupGate-Win32 v1.05
    * Origin: Agency HUB, Dunedin - New Zealand | Fido<>Usenet Gateway (3:770/3)
  • From druck@3:770/3 to Ahem A Rivet's Shot on Fri Mar 15 13:43:52 2024
    On 15/03/2024 10:51, Ahem A Rivet's Shot wrote:
    Make that 5 minutes * 500W/5W or 500 minutes which is indeed a long time but a lot shorter than the 150 hours you were expecting.

    If you want 150 hours, you need to be looking at a backup generator, so
    your UPS only needs to last as long as it takes for your generator to
    fire up.

    That's usually a couple of minutes for professional diesel ones, but as
    its home setup it might take you a few minutes to connect it up and pull
    the starter cord on a cheap petrol one.

    It might then take a few more minutes to drain the tank of the sludge
    that used to be fuel last time you used it, and to run to the garage to
    get some fresh petrol.

    It might take a few more minutes if your spark plugs have been fouled as
    you didn't clean it after use, and your air filter has a hundred
    different types of bugs living it.

    So make sure the UPS lasts an hour or 2.

    Oh and once you've managed to get it going, and it's making a tremendous racket, just remember everyone else in the neighbourhood who is without
    power will be turning to look in your direction...

    ---druck

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  • From Ahem A Rivet's Shot@3:770/3 to druck on Fri Mar 15 14:30:40 2024
    On Fri, 15 Mar 2024 13:43:53 +0000
    druck <news@druck.org.uk> wrote:

    On 15/03/2024 10:51, Ahem A Rivet's Shot wrote:
    Make that 5 minutes * 500W/5W or 500 minutes which is indeed a
    long time but a lot shorter than the 150 hours you were expecting.

    If you want 150 hours, you need to be looking at a backup generator, so
    your UPS only needs to last as long as it takes for your generator to
    fire up.

    Of course - but I don't think anyone wanted 150 hours they were
    just confused about Watts and Watt-hours and seemed to think that's what
    they would get.

    --
    Steve O'Hara-Smith
    Odds and Ends at http://www.sohara.org/
    For forms of government let fools contest
    Whate're is best administered is best - Alexander Pope

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  • From The Natural Philosopher@3:770/3 to Ahem A Rivet's Shot on Fri Mar 15 16:13:46 2024
    On 15/03/2024 10:51, Ahem A Rivet's Shot wrote:
    Watts
    per hour is meaningless.

    Not as a ramp rate for a power station :-)

    --
    β€œThe urge to save humanity is almost always only a false face for the
    urge to rule it.”
    – H. L. Mencken

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  • From Ahem A Rivet's Shot@3:770/3 to The Natural Philosopher on Fri Mar 15 16:44:06 2024
    On Fri, 15 Mar 2024 16:13:46 +0000
    The Natural Philosopher <tnp@invalid.invalid> wrote:

    On 15/03/2024 10:51, Ahem A Rivet's Shot wrote:
    Watts
    per hour is meaningless.

    Not as a ramp rate for a power station :-)

    <grin> Fair enough.

    --
    Steve O'Hara-Smith
    Odds and Ends at http://www.sohara.org/
    For forms of government let fools contest
    Whate're is best administered is best - Alexander Pope

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  • From Mike Scott@3:770/3 to bp@www.zefox.net on Sat Mar 16 15:27:04 2024
    On 14/03/2024 18:11, bp@www.zefox.net wrote:
    Mike Scott <usenet.16@scottsonline.org.uk.invalid> wrote:
    On 14/03/2024 15:51, Joe wrote:
    I'm using a cheap APC, I believe 650 or 750, with USB monitoring hookup. Also have my router connected (with VOIP) to keep
    communication possible for a little while (runtime abt 30 minutes). Battery replaced once, I believe it was some 7 years old.

    Somehow that makes no sense to me..... current 650 is 227 pounds (maybe plus >> VAT) on the APC website. 5 times the cost of the Pi. I'm sure it's a
    very nice UPS, but.... ???


    Sense or not, it seems to be a fact of life. The inverter/charger/transfer units
    I used have vanished from Amazon, replace by units with four times the power and
    double the price. Battery prices seem to have dropped very slightly, but are still a whisker over $200/kWH.

    A 12 volt to 5 volt stepdown converter appears to be less than $10, small 12 volt
    batteries range from $20-100 in the few AH range, a 12 volt 5 amp charger ranges
    from $11 to $50. The charger would be the iffy part, since a smart charger on a
    loaded battery is apt to get confused by what looks like high self-discharge..

    Something reliable for less than $100 will take both luck and ingenuity. One possibility is finding a used UPS unit in e-waste and replacing the battery.

    bob prohaska

    Seems the rechargeable bit is the issue. For my part, and purely to use
    as a short-term standby for the Pi until mains resumes or the system can
    shut down cleanly - I'd be happy with something with a bundle of AA
    cells or similar. I doubt a clean switchover circuit would be difficult
    to design, but my electronics knowledge is decades out of date :-{


    --
    Mike Scott
    Harlow, England

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  • From bp@www.zefox.net@3:770/3 to bp@www.zefox.net on Sat Mar 16 17:56:30 2024
    bp@www.zefox.net wrote:
    side, you could put it all downstream of the Pi power supply
    and skip line detection entirely. That's a big advantage.

    On second thought, this is probably wrong. If one connects
    to a Pi a 5 volt supply in parallel with a blocking diode
    and a 6 volt battery, the diode is still forward biased
    and will drain the battery eventually. Some kind of switch
    is needed, controlled by line detection.

    Maybe a three terminal regulator set for 5 volts out powered
    by a 9 (or higher) volt battery pack could be substituted.
    Still, one has to consider the idle draw of the regulator.
    TI's LM340 takes 6 mA roughly. Still, that's a smallish
    supply for a Pi. You'll likely want something larger.

    Apologies for the red herring!

    bob prohaska

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  • From bp@www.zefox.net@3:770/3 to Mike Scott on Sat Mar 16 17:35:24 2024
    Mike Scott <usenet.16@scottsonline.org.uk.invalid> wrote:

    Seems the rechargeable bit is the issue. For my part, and purely to use
    as a short-term standby for the Pi until mains resumes or the system can
    shut down cleanly - I'd be happy with something with a bundle of AA
    cells or similar. I doubt a clean switchover circuit would be difficult
    to design, but my electronics knowledge is decades out of date :-{

    Since I started mucking about with inverters the complexity of line
    detection has gradually dawned on me. I started out thinking of a
    simple SPDT relay with coil across the line. Line drops, relay
    goes to normal contacts, job done. With enough filter caps on
    the Pi to sustain it through a few line cycles maybe that would
    work. For a larger load the caps get big, if you want (as I do)
    to back up several different devices (DSL modem, router, switches)
    that amounts to a custom DC supply interconnecting all devices.

    If you want significant endurance (minutes or hours) capacitors
    become impractical. Primary cells in series with a blocking
    diode (6 volt battery with one silicon diode in series) would
    get you close to 5 volts with the diode drop. Maybe that's
    your ticket. The key is finding the right battery chemistry
    to give the voltage you need. Still, it's a handmade gadget.
    And, whatever voltage matching device you select must not
    drain the primary cells. I think a three-terminal regulator
    would cause at least some trouble on that count. On the good
    side, you could put it all downstream of the Pi power supply
    and skip line detection entirely. That's a big advantage.

    When line voltage drops (and returns) it's often noisy, dropping,
    returning and dropping again. Much better if the UPS takes over
    with a hair trigger and waits for a period of quiet before retiring.
    That's where the logic gets intricate.

    I puzzled over the custom DC supply versus off-the-shelf AC UPS
    approach and settled on the latter. For a single Pi, that no
    longer looks so attractive.

    Thanks for reading,

    bob prohaska

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  • From David Higton@3:770/3 to bp@www.zefox.net on Sat Mar 16 20:32:36 2024
    In message <ut4mge$30t2r$1@dont-email.me>
    <bp@www.zefox.net> wrote:

    bp@www.zefox.net wrote:
    side, you could put it all downstream of the Pi power supply and skip
    line detection entirely. That's a big advantage.

    On second thought, this is probably wrong. If one connects to a Pi a 5 volt supply in parallel with a blocking diode and a 6 volt battery, the diode is still forward biased and will drain the battery eventually. Some kind of switch is needed, controlled by line detection.

    Maybe a three terminal regulator set for 5 volts out powered by a 9 (or higher) volt battery pack could be substituted. Still, one has to consider the idle draw of the regulator. TI's LM340 takes 6 mA roughly. Still,
    that's a smallish supply for a Pi. You'll likely want something larger.

    It is possible to switch between mains and backup using MOSFETs, so you
    can get the voltage drop of the switching device arbitrarily low, and a switchover time of a microsecond or so - it doesn't need to be quite
    that quick, but it probably wants to be quicker than a mechanical relay.
    /If/ you want the negative line to be common, and the switch to be in
    the positive line, you need to use P-channel MOSFETS. And remember the presence and direction of the body diode, so you'll want to connect
    source and drain the opposite way round from what you might imagine.

    You'll need a reliable detector of the presence of mains, and probably
    also that the output is high enough before you swap back to mains.

    Most people are accustomed to working with N-channel devices and not
    thinking about the body diode, so you might find the mental gymnastics
    very hard, but it can be done!

    The prize is that normal running will definitely be from mains, even
    if the output voltage of the mains supply is slightly lower than that
    of the backup regulator.

    David

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  • From The Natural Philosopher@3:770/3 to bp@www.zefox.net on Sat Mar 16 23:53:28 2024
    On 16/03/2024 17:56, bp@www.zefox.net wrote:
    bp@www.zefox.net wrote:
    side, you could put it all downstream of the Pi power supply
    and skip line detection entirely. That's a big advantage.

    On second thought, this is probably wrong. If one connects
    to a Pi a 5 volt supply in parallel with a blocking diode
    and a 6 volt battery, the diode is still forward biased
    and will drain the battery eventually. Some kind of switch
    is needed, controlled by line detection.

    Maybe a three terminal regulator set for 5 volts out powered
    by a 9 (or higher) volt battery pack could be substituted.
    Still, one has to consider the idle draw of the regulator.
    TI's LM340 takes 6 mA roughly. Still, that's a smallish
    supply for a Pi. You'll likely want something larger.

    Apologies for the red herring!

    bob prohaska

    I think the chances of finding an 'ideal' battery are relatively slender.
    You are likely forced into some sort of 5v switched mode regulator - and
    its probably wisests at least for a single Pi - to have that permanently delivering power and just have the battery on permanent mild charge
    --
    The New Left are the people they warned you about.

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  • From Richard Falken@1:135/115 to Andriy D on Sun Mar 17 14:40:06 2024
    Re: Re: Backup power supply
    By: Andriy D to Richard Falken on Thu Mar 14 2024 07:57 am

    You mean full blown AC UPS, like APC used to do? Or do you know some well-kn brands producing USB UPS?


    Yes, I was thinking a full UPS with an USB port for control. APC has some models that would do. Cyberpower also does have some very nice ones for domestic purposes.

    --
    gopher://gopher.richardfalken.com/1/richardfalken
    --- SBBSecho 3.20-Linux
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  • From Richard Falken@1:135/115 to Mike Scott on Sun Mar 17 14:46:52 2024
    Re: Re: Backup power supply
    By: Mike Scott to Joe on Thu Mar 14 2024 04:32 pm

    Somehow that makes no sense to me..... current 650 is Β£227 (maybe plus
    VAT) on the APC website. 5 times the cost of the Pi. I'm sure it's a
    very nice UPS, but.... ???


    Well, any battery (without controllers or anything, just the battery) is going to be expensive as heck. I think the trick is using the same battery for a bunch of mini-appliances so you don't feel stupid spending many hundred bucks for backing a single machine worth 30 bucks...

    --
    gopher://gopher.richardfalken.com/1/richardfalken
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  • From Kees Nuyt@3:770/3 to usenet.16@scottsonline.org.uk.inval on Sun Mar 17 21:42:00 2024
    On Sat, 16 Mar 2024 15:27:05 +0000, Mike Scott <usenet.16@scottsonline.org.uk.invalid> wrote:

    ... For my part, and purely to use
    as a short-term standby for the Pi until mains resumes or the system can
    shut down cleanly

    Please note that the Pi still draws power after shutdown,
    because it has no power-off circuit of any kind.
    There is a small but significant stand-by current (not just any
    LEDs) that will eventually drain the UPS/batteries/whatever.
    A dumb power source should at least be over-discharge protected
    (think of protected Lithium batteries) or not be damaged by
    total discharge.

    Another issue: If grid power is restored before the UPS is
    empty, the pi will not boot automatically. It only knows how to
    handle unplug - replug the USB power.

    So a good solution should remove power from the Pi after
    shutdown, and switch it on again once the grid power is back.

    Like David Higton suggests, MOSFETS are great for that.

    --
    Regards,
    Kees Nuyt

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  • From bp@www.zefox.net@3:770/3 to The Natural Philosopher on Sun Mar 17 22:24:48 2024
    The Natural Philosopher <tnp@invalid.invalid> wrote:
    I think the chances of finding an 'ideal' battery are relatively slender.
    You are likely forced into some sort of 5v switched mode regulator - and
    its probably wisests at least for a single Pi - to have that permanently delivering power and just have the battery on permanent mild charge

    It's certainly the simplest solution from off-the-shelf parts.
    Standard dc-dc converter, standard battery, standard charger.
    No need for a handmade line power loss detector.

    Efficiency won't be great. For one, or even several, Pis
    that's not a problem. But it will likely be somewhere close
    to $100 for a halfway decent battery and charger.

    bob prohaska

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  • From Lars Poulsen@3:770/3 to bp@www.zefox.net on Fri Apr 5 14:13:34 2024
    On 3/13/2024 4:14 PM, bp@www.zefox.net wrote:
    For one Pi a 5 volt regulator connected to a battery
    that's held on a float charger is probably the cheapest,

    That is what I used for my CPAP which has a 12V input for use when
    camping. A motorcycle battery and a trickle charger.

    But since then, I installed a backup generator for the whole house, so
    the wife wanted the jerry-rigged UPS out of the house.

    -- Lars

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