While the observatory has mains power, our area is prone to blackouts from time to time. I have experienced 3 outages while imaging in the past 3 years.

This is a DIY online UPS. It comprises a DC regulated, variable voltage PSU (running off mains power) connected to a 54 Ah AGM battery and a 300w sine wave inverter (connected in parallel). To see how it's used currently see: http://www.pbase.com/gailmarc/image/153621600

In the event of a blackout, without the PSU, my current system will continue running from the battery (without any switching transients during the cutover) for approximately 1 hour. During normal operation, the PSU is set to a float charge of 13.8V ensuring the battery is maintained at full charge.