Will it be possible to provide short term power to the B2+ model with the following setup?

5V 2A 44W Uninterrupted Power Supply Alarm System Security Camera Dedicated Backup Power Supply 6-10 Hours


Micro USB 5 Pin Male To DC 5.5x2.1mm Female Power Supply Charging Cable Adapter

Will the micro-USB power adapter work for the pi?


I ended up getting a slightly different model which is directly pluggable into the socket, includes the rechargeable battery. Everything works fine in combination with the listed coaxial to micro-USB adaptor.

Yet, the question was not about specific products, it was more about a certain class of configuration, so the technical wording of the question would be Is it possible to power the PI with a mini UPS which is not built specifically for the PI and has a different power plug. Searching for mini UPS was what led me on the right track.

The answer is yes, it works with the given combination, and in unplugged state I get roughly 90 minutes of continuous MP3 playback with a connected 32GB USB flash stick.

  • 1
    Yes - IF the polarity is correct in both the UPS and the adapter and it all works happily (it provides enough current etc, 2.5A is sort of recommended for newer models though 2A should work mostly). The problem is there are lots of vaguely similar products on the market so users here may not have had experience with that exact product, probably why this usually not counted as on-topic
    – Wilf
    Jun 10, 2018 at 11:30
  • 2
    Actually asking if a specific product can be used for a specific purpose is okay -- what's off-topic is asking for recommendations for a specific product. E.g., "What UPS should I buy?" is off-topic, but "What should I look for in a UPS for the Pi?" is also okay. At least, this is how we've been enforcing it since forever (probably I should go edit that help page...)
    – goldilocks
    Jun 10, 2018 at 11:49
  • 1
    @goldilocks that would be awesome, other sites are a bit more trigger happy on flagging! Anyway, See also raspberrypi.stackexchange.com/questions/1360/… raspberrypi.stackexchange.com/questions/35/… (more for custom building)
    – Wilf
    Jun 10, 2018 at 12:15
  • It looks nice, except for the extremely long charging time, "If long time did not use this mini UPS, suggest 3--5months to charge it once." This is one of the funniest translation errors I've seen on that site.
    – NomadMaker
    Jun 10, 2018 at 12:17

1 Answer 1


There are several considerations for choosing UPS supplies for the RPi.

Surprisingly, one of those is safety. The RPi is small, portable and frequently used outdoors in areas subject to wet contact. National electrical codes (e.g., US NEC) often restrict voltages subject to wet contact. This means that using an indoor UPS to power your RPi would "work" but not be safe if the UPS was outdoors (e.g., in the rain).

Another important consideration is the output voltage of the UPS. Since an RPi in the field can be some distance from a line voltage power supply, the length of the wiring between the Pi and the UPS matters significantly. Although a 5V UPS can nominally power an RPi, it will fail to do so over long thin wires outdoors because the wire resistance will cause a voltage drop below the 5V required by the Pi.

For uninterruptable indoor power supply, your options are many given the ready availability of line voltage. Do be safe and consider electrical code (e.g., putting a UPS next to the bathroom sink for your RPi smart mirror would be shockingly bad). Although UPS products are available and marketed as such, you may find the convenience of rechargeable batteries more compelling (e.g., 12V lithium battery with USB outputs) if portability is important.

For uninterruptable outdoor power supply, consider using batteries (e.g. 12V LiPO with USB output) and wiring that comply with national electrical codes. Not all rechargeable batteries support simultaneous charge/discharge. Consult SE Electronics for more information.

Always consider RPi power limitations

  • it's meant for indoor use, as a motion sensor, close to the power outlet
    – ccpizza
    Jun 10, 2018 at 13:56
  • Thanks for the clarification. I've broadened the indoor advice to include my own solution which is a lithium battery. I use 12V lithium batteries because sometimes I have 12V as well as 5V needs. There are also 5V rechargeable batteries which would also work. Note that not all rechargeable batteries can serve as UPS because UPS requires simultaneous charge/discharge.
    – OyaMist
    Jun 10, 2018 at 14:14
  • For really low power stuff you can use 3.7V batteries and a boost converter - they can be got with handy little boards like adafruit.com/product/2465
    – Wilf
    Jun 10, 2018 at 18:00

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