Using a UPS is highly recommended because power that fluctuates or occasionally spikes can damage anything electronic. Although we try to minimize writes to the flash card, if power is lost in the middle of a write then there can be sector damage to it.
We are really sorry for the FlightFeeder corruption problems and mitigating them has been the #1 priority of our FlightFeeder development the last several weeks. With version 5.0 of the software, which almost all FlightFeeders now have, the SD cards are run in a read only mode for normal operation. However it is still possible that a card in read only mode can become corrupted if power is cut at the wrong time.
We are wrapping up version 5.2 of the FlightFeeder software and will be rolling it out to all the FlightFeeders in the next few days. This will add keystrokes that can be sent from a USB keyboard to trigger a halt or a reboot, and a web-based thing as well that will work through the FlightAware status page for your FlightFeeder. Using one of these mechanisms to shut down the FlightFeeder before moving it or whatever should basically eliminate the risk of corruption from removing power.
We highly recommend that the FlightFeeder be run on a UPS if possible. Our prototype has been running since March of 2013 without any problems, but it’s been on a UPS the whole time.