Using a power bank as a 5V UPS for a clock

Discussion in 'Electronics & Electrics' started by Ratzz, May 10, 2019.

  1. Ratzz

    Ratzz Member

    Joined:
    Mar 13, 2013
    Messages:
    8,024
    Location:
    Cheltenham East 3192
    Hi guys,
    I have a specific LED clock that I'd like to use built into my custom wooden case.
    The clock operates on 4x standard AAA batteries, or USB power via the supplied wall wart. The batteries will continue to run the clock if the USB supply is removed.

    However, using a set of Energizer Advanced batteries, with the clock on constant display and the USB supply removed, the batteries last 2 days. The clock does not say (in the very limited instructions) to use rechargeable batteries, so I am going to assume that the default is the USB power, and it will switch to batteries if the power is removed, but does not actually charge the batteries.

    Since Eva is a power nazi and regularly shuts off the power to our computers at the wall, I want this (specific) clock to be capable of running on batteries alone for up to 24hrs at a time, and more than just a couple of times :D. 12hrs would be the general maximum, but a bit of headroom would be nice. I guess I could use a different clock, but most clocks with battery backup don't display when the power is removed, just keep the time settings, and this particular clock is perfect for my needs so I'd really like to use this specific clock, not a different clock, anyway.

    My thoughts are to use a power bank as an inline UPS kinda thingy, so running the clock 24/7 from the power bank and charging it simultaneously when the power is on. I'm pretty sure most power banks are not designed for this kind of constant use though, even if (and I'm pretty sure they don't?) they can charge and discharge at the same time.

    Obviously I don't want to spend a fortune on a proper UPS, so I'm hoping I can roll my own.

    Any thoughts?
     
    Last edited: May 10, 2019
  2. elcarter1

    elcarter1 Member

    Joined:
    Feb 24, 2007
    Messages:
    567
    Location:
    Adelaide
  3. OP
    OP
    Ratzz

    Ratzz Member

    Joined:
    Mar 13, 2013
    Messages:
    8,024
    Location:
    Cheltenham East 3192
    No need for it to fit into the clock, plenty of external room for a battery pack. The thing that concerns me here is not how to charge a battery pack from USB.

    I don't want to have to open the back of the case regularly to service anything - recharge the batteries,reset the time on the clock, etc.

    If its going to run on battery power alone, I will need the battery to have a passthrough.. charging and discharging simultaneously.

    I would imagine that any kind of rechargeable battery/pack is not designed to be used in this way?

    Either that, or it defaults to battery power when the USB power is off, and runs from the battery pack until the USB power comes back on, and then recharges the batteries AS WELL as providing supply to the clock.

    A 'normal' bedside LED clock uses an internal battery to simply keep the time, but doesn't display until the power comes on, due to the extra power demand of the display, I want to keep the display permanently lit, even when on battery.

    I've watched the videos on your link, but it seems to me that these circuits simply provide a charger to the batteries. I'm not sure how solves my problem, unless I am misunderstanding something here?

    Are you suggesting a dual circuit, where the USB circuit charges the internal batteries while providing power to the clock, but there is no passthrough, so when the USB power is removed then the recharged batteries take over the power supply duties using the clocks own internal circuitry?

    Some kind of diagram might be useful to me here, I am a total noob at this stuff.

    Something else that has occurred to me is using a 6V SLA battery, so at least I can get some extreme battery duration and simply have to charge the battery every 6 months :D but even this is not ideal.
     
    Last edited: May 10, 2019
  4. shredder

    shredder Member

    Joined:
    Dec 26, 2001
    Messages:
    11,215
    Location:
    Dec 27, 1991
    Sounds complicated. Why not just a 5v wall wart to USB?
     
  5. OP
    OP
    Ratzz

    Ratzz Member

    Joined:
    Mar 13, 2013
    Messages:
    8,024
    Location:
    Cheltenham East 3192
    Because Eva is a power nazi and shuts the power for our computer desk down at the wall whenever she can get away with it.

    Yeah, this means the batteries will take over.
    However, since a set of high end batteries lasts 2 days if I use only batteries (because LED display), then sharing between power and batteries means I'll be changing batteries like once a week.
    Since its being built into the case, that will mean opening the case every week and changing batteries, in a really awkward spot. I want them to charge themselves when the power is on.

    There is fuck all standby power in use, but that doesn't convince her. Its a fucking pain, I use my wireless headphones for many hours a day, and I often get flat batteries because they didn't get a chance to charge during downtime. Phones too.

    Hell, she even insists on switching the toaster and electric jug off at the wall when not in use (she even unplugs them !! ), and they use zero power when off.
     
    Last edited: May 11, 2019
  6. mjunek

    mjunek Member

    Joined:
    Apr 1, 2003
    Messages:
    863
    Location:
    Ashfield, Sydney
    Related, but not quite - Put a real UPS on all your kit. It'll scare the shit out of her when it starts beeping every time she turns off the wall power, and the only way to shut it up is to turn the wall power back on :)

    Re: USB Power Banks - one of mine shuts off the external power when charging, and the other one will keep charging whilst supplying power. I think it's luck of the dice. Note, that if it goes flat, when turning the incoming feed back on, the power bank needs to be turned back on for it to work again, it won't just come live again.
     
  7. OP
    OP
    Ratzz

    Ratzz Member

    Joined:
    Mar 13, 2013
    Messages:
    8,024
    Location:
    Cheltenham East 3192
    Could you post the brand and model of the one which will keep charging while supplying power mate? That would suit my purposes perfectly I think, provided it has overcharge protection. Would the batteries suffer using it as a permanent inline feed?
     
  8. mjunek

    mjunek Member

    Joined:
    Apr 1, 2003
    Messages:
    863
    Location:
    Ashfield, Sydney
    Oh it's some yum-cha thing that I got off ebay. I dont think it has a brand. But I'll double check.

    Honestly - I'm not sure how the batteries would go - given they are all lithium style, I would imagine it's no different to keeping a mobile phone or laptop plugged in and running all the time.
     
    Ratzz likes this.
  9. dakiller

    dakiller (Oscillating & Impeding)

    Joined:
    Jun 27, 2001
    Messages:
    7,794
    Location:
    Gippsland
    So instead of confronting your partner, you want to rig some elaborate setup? Is she that bad that you can't talk to her about this?

    (Fix the root issue)
     
    Jazper likes this.
  10. elcarter1

    elcarter1 Member

    Joined:
    Feb 24, 2007
    Messages:
    567
    Location:
    Adelaide
    Sorry should have mentioned it wasns't do this and this would work post. Just a push in a possible direction.

    In essence yes, that would be my preference. One usb cable to the clock as per usual and all you use the already internal battery area to house the 5V pack.

    Think of the battery as a 5V float that is just in top up charge mode until the power drops and then provides the power until the 5V lines re-activated (eva goes away) and then recharges.

    If you don't want to open the clock and happy to have some sort of pack somewhere you could just permanently power the clock from the battery and then use the wall charger to maintain the battery pack but the lithium USB power pack option trumps this for simplicity, power depth, recharge cycle and compactness.

    That said you loose point for no DIY :) and it will cost more.
     
    Last edited: May 11, 2019
  11. OP
    OP
    Ratzz

    Ratzz Member

    Joined:
    Mar 13, 2013
    Messages:
    8,024
    Location:
    Cheltenham East 3192
    Habits of a lifetime, women, not worth the angst :lol:

    That I think I can do. I think this is the best option, my only concern is potentially overcharging the batteries. I'll do some googling and find something with overcharge protection.
     
  12. shredder

    shredder Member

    Joined:
    Dec 26, 2001
    Messages:
    11,215
    Location:
    Dec 27, 1991
    Understood! You're quite right - the compromises of a long term partnership.

    You can alter the person or alter the clock. The clock won't engage in a massive protracted argument with you and hold it against you for the next 3 days, then just go back to what it was doing in the first place anyway. :lol:
    Sounds good. I was looking at the Xiaomi 'Mi' range (e.g. excuse the nz link, that's my turf), they seem to have the necessary specs.

    "Bypass charging" or "pass through charging" is the Google-able term for the ability to simultaneously charge the bank and the clock.
     
  13. mjunek

    mjunek Member

    Joined:
    Apr 1, 2003
    Messages:
    863
    Location:
    Ashfield, Sydney
    Only 3 days? Damn, I wish I had it so lucky :D
     
  14. OP
    OP
    Ratzz

    Ratzz Member

    Joined:
    Mar 13, 2013
    Messages:
    8,024
    Location:
    Cheltenham East 3192
    So in the end I bought one of THESE TL-PB10000 Power Banks from Umart. Has passthrough and all the necessary protection circuits, I'll simply use it inline from the USB power.
    OK, lazy I know... but hopefully it will do the job. Cost more than the damn clock did though :lol:

    I'll report on how well it works when it arrives and I've tried it for a week or so.
     
  15. dakiller

    dakiller (Oscillating & Impeding)

    Joined:
    Jun 27, 2001
    Messages:
    7,794
    Location:
    Gippsland
    I got a similar clock. Bigger version that shows temp as well as time. Worst UI on a device ever, there are so many features that the buttons and display make no sense to what you are doing to it. Every DST time change has me fucking it up, hard resetting it and trying to google a manual to set the thing back up, only to have it alarm and beep at 3 in the morning.

    Also, it can’t keep the time for shit either, runs slow by about a minute every other week.

    At least it looks nice and was cheap

    (Wonder if there would be a market for them to be made better?)
     
  16. OP
    OP
    Ratzz

    Ratzz Member

    Joined:
    Mar 13, 2013
    Messages:
    8,024
    Location:
    Cheltenham East 3192
    The clock displays temp too. It can be set with the LED display sound activated, but I prefer it with the display permanently on. The sound activation is a joke, doesn't work well at all.

    Every minute or so, it displays temp for about 3 seconds and then goes back to time. It seems to be keeping pretty decent time so far but the temp is suspect, it appears to display temp about 2° higher than our gas heating thermostat. Of course that could be due to location though.

    Fuck it, near enough is good enough. You are right about the UI, it sucks, but once I have it mounted with the battery backup, I hope I'll rarely touch it again. Just for DST changes I hope.

    The temp function will be displaying the case temp in the highest part of the case, where it will be mounted, so it won't be showing room temp anyway. The sensor will be within the case.

    The main reason I bought it is because it will be permanently mounted in my custom MDF computer case, beside the monitor which is also built into the case. It's exactly the size I want, has a bright and reasonably large display, and is totally flat on the display surface.

    I've taped some of the veneer I'll be using for the case over the display, and its bright enough to clearly shine through the veneer :thumbup: so I'll be installing it with the display flush on the front of the case then ironing the case veneer over the clock too, for a really cool integrated look I hope. It will basically be like a wall clock for our main living area, where the computers are located.

    I'll have reasonably good access to the back, where the buttons are, it will only require removing the case back, which will be very easy. No big deal to change time occasionally for DST. UI defaults to main time as the first option, with both up and down buttons, so DST changes will be literally 3 clicks, and I wont even need to cycle through other options, so the alarm/s won't be accidentally set.

    I'm looking forward to seeing it mounted, sometime this week I hope. I'll report as to how well the battery backup works, and post pix of the mounted and veneered end result.
     
    Last edited: May 11, 2019
  17. caspian

    caspian Member

    Joined:
    Mar 11, 2002
    Messages:
    9,891
    Location:
    Melbourne
    are you married at all?
     
    Ratzz likes this.
  18. dakiller

    dakiller (Oscillating & Impeding)

    Joined:
    Jun 27, 2001
    Messages:
    7,794
    Location:
    Gippsland
    Yes. Maybe not long enough?
     
  19. caspian

    caspian Member

    Joined:
    Mar 11, 2002
    Messages:
    9,891
    Location:
    Melbourne
    until I got married I didn't even realise there *was* a way to put milk into the fridge wrong.

    I have only been married coming up on 10 years but one thing I learned fairly rapidly was to pick my conflicts with care. you'll still lose most of the time, too. :lol:
     
    Ratzz likes this.
  20. Privatteer

    Privatteer Member

    Joined:
    Mar 19, 2006
    Messages:
    796
    I invested in 2 similar with rechargable Li-ion battery due to all the power outages I get about 2 years ago.
    This one is not too bad UI and I can set it without a manual. The other is horrible.

    At least both alarm even if the power is off and wake me.
    The temp reads about 2 degree high due to internal location.
     
    Last edited: May 15, 2019

Share This Page