Hao Jie Arduino Uninterruptible Power Supply (UPS) | Chan's Kingdom
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Saturday, December 12, 2015


Arduino Uninterruptible Power Supply (UPS)

Recently a friend of mine asked me to design a simple Uninterruptible Power Supply for Arduino using some handphone battery ( Li-ion) and handphone charger.

I decided to use a TP4056 charger board to charge the battery, while using a P-MOSFET to control when will the battery provide power to a 5V Step Up Converter.

The schematic shows the 5V from a handphone USB charger feeding a 5V Boost Converter, which powers an Arduino Uno. The 5V will also charge the Li-Ion via TP4056 board. If the USB Supply is gone, the P-MOSFET will be switched on and the Li-Ion battery can power the Boost Converter.

( on second thought, now I am thinking about the usefulness of the P-MOS. I was thinking of switching the battery on and off but now I think it serves no purpose... LOL)

Anyway, the 2 diodes are 1N5158 , I forgot to change it on the schematic. I think the P-MOS can be eliminated because the 5V from the USB would have prevented the battery from supplying power anyway.

This is my end result on a perf board. My friend says that it is working fine, at least until now. (I have no confidence in my design).


p/s :for the improved design, go to http://chanskingdom.blogspot.my/2016/10/arduino-uninterruptible-power-supply.html


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Author: Chan HJ
An enthusiast in papercraft. Paper model designing sounds fun too! More about me at my Blog Bio or


  1. I'm glad you like this. I have since then improvised the design. The P-MOS is not necessary.

  2. This is amazing. I would have never thought of building my own ups. Is this the best uninterruptible power supply maker online today? Thanks for sharing! Have you posted your improved design?

  3. Surely it is not the best. :)
    No, I didn't really improve it, I merely removed the PMOS from the circuit as it serves not purpose.

  4. Could you share your improved design with us?

  5. Hi, I just wrote a new post about the new design. You can view it here.
    Cheers :)

  6. This comment has been removed by a blog administrator.

  7. What if you just added the switch without removing the P-MOS? The switch version you currently have, has the option to keep switch ON while connected to USB, and so you have 2 different voltages meeting after diodes.

    1. Hi, with the diode only the higher voltage would be powering the converter. So the PMOS is really not needed.