I have an AC3... LOVE IT!
I have a DC8 and a HighCapacity DC4 for it.
I have mine connected to my network and run Aqua Notes for trending data.
I also have it send my phone Text Messages if I have perameters fall out of normal specs. It also has 2 power inputs.
Plug the main into the wall, second into a UPS. When the main power fails, the AC3 sees that power is lost and you can have it shut down all unnecessary items so that you maximize your battery life.
For instance I will have a Air pump that will be turned on when power fails...most other pumps and equipment will be shut down (skimmer, reactors, main pumps, lights, etc) This wil ensure that I have some flow and air for the max amount of time.
Of course it will text me to inform me the power is down. (you have to have your network on UPSs too)