Uninterruptable Supplies

I’m sure most of us who play with the likes of Raspberry Pis and other SBC boards as well as other devices, have looked at uninterruptable supplies at one point or another – I often use the little battery powered chargers you get for phones – and until recently I thought that was a universal solution – having powered my Pi in Spain for many months now on one of these and we get awful power cuts there – no problem.

Lithium chargingThen someone pointed out to me that SOME of these units turn off the output when charging. Well of course they don’t ADVERTISE that – so that’s a problem if you’re looking for cheap options.

So today I received from BANGGOOD a cheap circuit board that promises to do the job. As it happened my one and only Lithium in a torch left in storage over the winter had kicked the bucket… but I remembered I had a spare but dead battery pack for one of my laptops – and proceeded to open it up. Sure enough half a dozen Lithiums in there.

I took one out that looked clean – dead. Put it on my big power supply for a couple of minutes at 2 amps – it looks ok.  So now I’ve attached it to this little board and plugged the board into a decent USB supply. one of the little chips is getting a little hot as it pumps power into the board but I think it will be fine (update once the battery ha some charge this cooled off – then running a FriendlyArm SBC nothing at all got warm).   So after it had been on for a while to give the battery a chance to get some power, I plugged an SBC into it’s output. You can see all of this in the picture above. Worked a treat and the little board settled into a blue-flashing-light mode after a few seconds.   I repeatedly disconnected the incoming power – no difference, the SBC just kept going.

So if you want something new to play with…. and you’re aware of the dangers of going within 100 miles of Lithium batteries – you might want to give this a shot. At £2.37 inc shipping – you can’t really go wrong provided you give it a damn good test before doing anything serious with it.  I think I may make a little bank of them with the remaining Lithium batteries from my power pack.



31 thoughts on “Uninterruptable Supplies

  1. I was looking for a cheap solution for a long time 🙂
    I order from this module and will try
    Thanks for the sharing

    1. There's a 4056 and several other chips on the board. The 4056 is presumably the one that handles charging - I'm not sure what handles voltage conversion to bring the output up to 5v - whatever it is, it does a good job.

  2. Would this be a reasonable option for solar charging?
    I'm looking to power a project with a couple of 18650 cells, with a solar panel to charge them, but I was running into the "no output while charging" situation you described.

    1. I see no reason why not but there is a pair of input pads - I'm wondering if they'd be better suited to variable input voltage than the usb input. Perhaps someone familiar with the 4056 could comment?

      1. I'll rephrase that - it seems like the chip is expecting something around 5v input... so you'd need an extra stage - a switching downconvertor - mind you, they're only around £1.50 - I've seen them handle an amp output - taking in anything from 5v to 30v - might check the same supplier. Each of these stages of course reduces efficiency but if you have a big enough solar panel (as, funnily enough I do - I've a couple of 12v (generating up to 18v) 40w panels... I dare say this board and one of those step down boards together would do the job for solar.

          1. Agreed on that tiny solar cell. I have one from Ray-o-Vac, made for outdoor trail cameras, that I want to use. Just took it outside with my meter and it did a steady 11v at 105mA, so with a step-down converter, I should be in good shape.

  3. Does the 'Mini USB To USB A Power Supply Module' have a status pin that you can connect up to one of the GPIO pin's on the SBC and shut it down after x seconds when it is on battery, like a normal ups?

  4. I have something similar for my projects for recharging but I've found I can power my project at the same time I'm charging although the device is battery powered and the mains just tops it up.

    I'm using to power my remote temperature display so that I just keep it on top of a QI wireless charger pad and it will run for around 4 days when removed. (I'm sure I could get it to run longer if I revisit the code)

  5. I'm still searching for my perfect Pi UPS. For something so simple, it seems many people want to make it really complex. I think I'll end up running one of them from one of the little switchmode "buck" regulators that you can get for a few dollars from China. I can then diode or a 9v power supply and a pack of 8 x 1.2v NiMH batteries onto the input to the regulator.

    I came across this project - I'd be interested to see if anyone else is using one? https://pi.gate.ac.uk/pages/mopi.html

    1. The most likely cause here is that you did not install as user Pi and/or you were not sitting in the /home/pi/.node-red directory when you installed it.

      The folder should be in /home/pi/.node-red/node-modules folder. Just delete the folder and try again.

  6. This is a great little board. It's been working well for me for the last 3 weeks.
    I noticed one potentially troubling behaviour, though:
    I have a bank of three 18650 cells connected in parallel, with an Arduino and sensor shield.
    I left it running overnight to drain, which it did. The Arduino, of course, shut down.
    I connected it to power to charge, which it did, however, the power to the Arduino did not restart until the Arduino was disconnected and reconnected.
    I need to do some more testing to see if I can reproduce it.

      1. Wired up another module, this time to a single 18650 and attached my Arduino and shield (about 1.8 A load) and let it run down.
        When I plugged in charging power, once again the Arduino did not come back to life automatically. I let it charge for a bit and it still did not. I pressed the Arduino's reset button and this didn't work, but disconnecting and reconnecting the USB *did* let it restart.

  7. Thank you for posting about this little power supply board, Peter. Just what I was looking for...

    Cheerful regards, Mike

  8. An outstanding share! I've just forwarded this
    onto a friend who has been doing a little research on this.
    And he in fact ordered me dinner simply because I found it for him...
    lol. So allow me to reword this.... Thanks for the meal!!

    But yeah, thanx for spending time to discuss this issue
    here on your web page.

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