On backup power after removing main power from Efis, I get the message to press any key to keep from shutting down which I know us normal since its switching initially to backup power to give the option. Then it seems consistently about five minutes later will get the same message about shutting down. Is this normal? Didn't see anything in manual regarding this. Backup volts/volts 2 shows 12 volts, is wired to pin 6 of expansion cable.