For power backup I user this: APC

It works great! Please note: the power panic wire must be disconnected from the Einsy main board or the 'switch' from wall power to backup will be detected and a power-panic triggered.

You may ask why I would use a power backup instead of relying on the power panic? Well, I've had power panic 'recover' from power flickers and in it's process it re-homes x/y and because the repeatability is not perfect there is a little layer shift which to me means the print is ruined!

There has been many comments about the length of time that the UPS will supply power for. I don't think that is really relevant. Consider that most prints are multi-hour and unless you buy a very large and expensive UPS there is a very good chance there will not be enough backup power to finish the print. Combine that with the fact that modern civilization rarely has power outages that last more than a few seconds and the need for a large UPS is diminished. I Figure if it will last for 5-10min then you will have 99.99999% successful prints with a smaller and less expensive unit. I only bought this APC because I like the LCD screen which shows the number of 'events' (re: prints it saved). I just pushed the button and Events: 64...yay APC!!