Testing a Pi UPS module

Conclusion

Equipping the Raspberry Pi with an emergency power supply is a good idea, especially for those who are using the Raspberry Pi in a way that could lead to a hard shut down – for example, when the Raspberry Pi draws electricity from the ignition of a car or via the USB port on a television. The Pi UPS gives the Raspberry Pi the necessary time to shut down properly; however, the manufacturer currently offers this software only for Raspbian. Thus, users will need to experiment with the software to run it on other distributions.

Everyday use of the Pi UPS reveals a number of weaknesses, in large part because of the design (see the "In Brief" box for more details). The battery provides energy to the Raspberry Pi in the event of a power loss, but the electricity only flows in one direction. Pi UPS does not offer a charge function for the battery.

In Brief

During the course of this test, I used a Raspberry Pi model B on which Raspbian had been newly installed. I observed that the UPS triggered a shutdown after the power supply was removed. However, then I saw an immediate restart driven by the battery. This was followed by a signal from the UPS to shut down, after which the computer did a restart. In other words, I observed an ongoing cycle of shutdowns and restarts that continued until the battery was empty. This behavior stopped when the board was exchanged.

Additionally, those who have purchased the UPS complain of a continuous discharge of batteries within just a few weeks of use  [5]. To guarantee a fully charged UPS, the Pi UPS would do better to work with lithium ion batteries, as do other UPSs [6].

Infos

  1. "Using the Raspberry Pi to Control Digital Information Screens" by Wolfgang Dautermann, Raspberry Pi Geek, Issue 6, 2014, pg.  42: http://www.raspberry-pi-geek.com/Archive/2014/06/Using-the-Raspberry-Pi-to-control-digital-information-screens
  2. Installation instructions: http://www.piups.net/support/
  3. Pi UPS: http://www.piups.net/
  4. Pi-UPS monitor app download: http://www.piusv.de/support/piusvmonitor.deb
  5. Poor battery life: http://piusv.de/forum/viewtopic.php?f=27&t=21905
  6. Uninterruptible power intelligent supply (UPiS): http://www.pimodules.com/_pdf/UPiS%20Module.pdf

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