Hello:
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Almost 2 years ago I purchased a Battery Backup unit.
  <! variously identified as ES650, BE650MC(FL1206), 3B1147X38747.> </!>
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When I installed it, my connections were ..
<br>  .- desktop computer tower connected to "Master" outlet
<br>  .- monitor connected to "Controlled by Master" outlet
<br>  .- USB alert connection and software not used
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When I initially tested it at that time,
<br>   then I observed the following mode of operation ...
<br>  .- when the city power was shut off,
<br>      then the computer tower stayed running and the monitor went off;
<br>  .- when the city power was turned back on,
<br>      then the computer tower was still on and the monitor came back on.
<br> These were the expected results.
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While we have had power interruptions over the intervening period, the computer was never on at those times.
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Just recently, the city power failed and came back on within a few seconds.
<br>Two of our household digital clocks reset to 1200 and then continued running from that time. The analog clocks were NOT noticeably changed.
<br>HOWEVER, BOTH the computer tower and the monitor went off and did NOT come back on when the city power resumed.
<br> These were NOT the expected results.
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Pressing the power-on button on the computer tower then re-booted it and turned  the monitor back on.
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My immediate analysis at the time was that the backup battery had gone weak and thus the computer shut down resulting in there being no load on the "Master" outlet and this keeping the monitor off. It seemed like a simple explanation at the time.
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BUT, the next day I set out to test the system and learned that the mode of operation was the SAME as had been experienced when it was new.
<br> They were the expected results.
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My second thought was that there was something unique about the characteristics of the city power failure; perhaps the short period of being off; but that makes little sense.
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Further testing indicated that the normal line voltage was 122vac and the voltage from the battery backup was 113vac.
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<br>So my third thought was that perhaps the computer sensed the voltage decrease and shut down. That would have explained its not coming back on and also the monitor's not coming back on; that made pretty good sense EXCEPT for the fact that the testing showed that the results were as expected and initially experienced.
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Have always enjoyed the peace-of-mind feeling of having a battery backup in case of a power failure, BUT ....
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At this point I'm at a loss for thoughts about a possible explanation for the UNEXPECTED result when the REAL power failure occurred.
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Your thoughts appreciated.
Thanks,,