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I got an Arduino project that need a constant source of power. Rather than dealing with batteries, I want to use a power bank like this:

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Better yet, I want to keep the power bank plugged in to the wall outlet using a wall charger like this:

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The USB wire coming out of the power bank, I can modify it and connect it to the 5V on the Arduino (Pro Mini 5V version). Is it safe to do so? The application uses a stepper motor that draws around 200mA and only runs intermittently.

Thanks

  • you will possibly kill your power bank faster, unless it has a pass thru circuit (does not discharge while plugged in and fully charged). i keep my rural Arduino PWS (weather station) powered like this all the time, because we have power outages on an almost daily basis. – tony gil Jul 24 at 15:49
  • what’s the load? is it enough to drop voltage and confuse your charge controller? if yes, it becomes a fire hazard. the USB battery needs to output 5V when plugged in, and mustn’t discharge the batteries to do this. use your multimeter to discover the truth! – user2497 Jul 27 at 3:49
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Yes you can. A promini will run very well on 5V from a wallwart. Connect 5V to VCC (not RAW or VIN). You can also find wallwarts with 2.1mm/5.5mm plugs, and a mating barrel jack adapter that ends in screw terminals so you don't have to try hacking up a USB cable.

Power bank, you will have to play games to convince it that something is connected and drawing sufficient current to keep it turned on.

Wallwart example https://www.mpja.com/5-Volt-DC-Plug-Power-Supply-4A-Regulated/productinfo/18520+PS/

Barrel jack to screw terminal adapter example https://www.mpja.com/55_21mm-Power-Jack-Screw-Terminals/productinfo/19454+PL/

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Yes, that is my standard setup for Arduino and Raspberry Pi.

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