UPS to provide backup power to remote controllers

I purchased a 300 watt UPS from Office Max for $60.00 installed it in a remote pump station control panel that has a AD PLC, radio (for communicaton) and ultra-sonic level control. I thought this would be a cheap way to provide data (tank level etc.) for at least an hour or so during a power failure.

The problem with this I have come to find out is that the UPS battery output on most of the cheaper units is a step wave (square wave) that will not provide enough voltage for the plc to see a 120v input, the battery output will only read 80 to 90 volts on a volt meter even though the spec's on the UPS read 115v +/- 8%.

The UPS that I bought was an APC and after talking with their tech support was told that I would have to buy the more expensive one for about $320.00 to do the job correctly and that is would be larger in physical size which is harder to fit in the panel. I was told by a friend that PK electronic's out of Arizona made one for around $100.00 that would do the job (called the Blackout Buster) but I have now found out they are out of business at least temporarily.

Would anyone have any suggestions for where I could find a UPS that provides true sine wave for around $100.00 as I would eventually need about 50 of these units and at $300.00 a piece that adds up to lot of money.

APC

Try this address, they advertise 90% discount and they have a couple hundred of the APC SU650. I have used this model to power A-B PLCs and Panelviews. As I recall it lasted about 40min for the PLC but a lot less for the PV.

http://www.logicbox.com/catalogue.phtml?cat=POWR

Roger

Just a Thank you to rogerhollingsworth

I wanted to thank rogerhollingsworth for directing me to Logic Box, a company that sells refurbished UPS's (new batteries). Just like you stated thier prices are very low and in addition the company is easy to deal with. You were the only reply to my request but you hit the bulls eye, thanks again!