HD DVR dedicated inverter

I have been using a UPS to power my TV and Sat. Works great switches between AC and battery with out missing a beat. Done it for years. Last winter my UPS went up in smoke. Transformer cooked. I bought a new one in TX. seemed great while hooked to shore power. But on the trip home while charging house batteries found out it doesn't like it while charging over 14 volts. Warning alarm on the UPS goes off until charging stop or the voltage drops back down to the 13 volt range. I am going to replace it with the Samlex PST300 and a Xantrex 15amp transfer switch. The only problem I see is the time lag in the transfer switch might drop out the Sat.