I'm collecting prices on some good UPS's. Since I am tailoring this for momentary outages, I was hoping SuperCapactitor UPS's would work well, but it seems their price points are still quite high. I found one that is tailored to run for 15 seconds or less, I hope perfect for dealing with a PowerWall cutover for my computer server that has a large power supply:
Marathon Power, SuperCap UPS System, made up of two parts: part# ARTE-3000-01, SuperCap 3kVA (2100W) NEMA IN/OUT Electronics Module (the inverter) (they also have a 1kVA (700W) model), and part# ACPR-1058-96-120, 3kVA SuperCap Energy Storage Module (the capacitors). (They also sell hardwired (no plug) or plug (NEMA), 120VAC or 240VAC (single phase), 700W or 2100W.) I got a quote from Arrow.Com for those for $1,350.38 for the ARTE-3000-01 plus $2,575.29 for the ACPR-1058-96-120 for a total of $3,925.67 (not including sales tax and shipping). I'm waiting for a quote back from my official distributor which may or may not be much different. Literature at
Marathon Power - Supercapacitor UPS - Battery-less True On-Line UPS
Marathon Power told me "The initial cost (for the SuperCap UPS System) is higher than a comparable (battery UPS) of the same VA rating, but there is no battery replacement, major system maintenance or hazard waste disposal." Also, I think the supercacitors are supposed to last longer than the batteries, but we don't have a lot of data on that yet.
I might be looking at the above solutoin with capacitors, or try going with an exsting battery brand UPS from somewhere. I would want high quality, a fairly healthy KVA rating, and handling only very short outages of seconds in length (as opposed to the old UPS battery regimine of "enough time to do a proper shutdown and transfer all clients to another cloud provider off-site"). I think requirement begs more for capacitors than batteries.