I found out the hard way, do not plug your laser printer into the battery side of your surge protector. It drains the battery.
Even if a UPS battery is large enough, manufacturer still quietly recommends not powering a laser printer. A UPS in battery backup mode is some of the 'dirtiest' power inside a building. Since electronics are so robust, then that 'dirty' UPS power is also ideal power. But 'dirty' UPS power can damage small electric motors and power strip protectors.
For example, this 120 V sine wave UPS outputs 200 volt square waves with a spike of up to 270 volts. Again, ideal power to electronics. And a problem for protectors and motors.
A utility also demonstrates how 'clean' AC mains sine waves are replaced with 'dirty' power when the UPS switches to battery:
http://www.duke-energy.com/indiana-business/products/power-quality/tech-tip-03.asp Connecting to 'surge protector' outlets is electrically same as powering the laser from any other receptacle on the same branch circuit. No magic device is between a wall receptacle and those surge protected outlets. Open it up. It remains a direct (hardwired) connection. No magic exists inside that UPS.
