sure, ASIN B00EAIG17E "DROK 110V 220V UPS Battery Backup Uninterruptible Switching Power Supply 12V 120W 110V-240V to 13.5V DC 50/60Hz with Battery Interface fo

sure, ASIN B00EAIG17E "DROK 110V 220V UPS Battery Backup Uninterruptible Switching Power Supply 12V 120W 110V-240V to 13.5V DC 50/60Hz with Battery Interface for Charging" When you remove mains power it switches over instantly enough that the computer doesn't notice. There's no serial port on it so the computer has no way of knowing that it's on battery - but it was also only $26 shipped. No wires or battery or anything. I happen to have a few of the trimpot breakouts specifically for setting voltages, so i just made sure that when the PC was powered it was getting the correct voltage without sagging below 12.2ish under load at the output terminal of the PSU. It also has a little trimpot on the board for adjusting the voltage. P.S. I'm not sure if Drok has a lot of knockoffs or not, i do know that i like that brand well enough, never had anything bought from them break in a weird way. I have slagged a few of their "waterproof" 24VDC boost converters, though!