After a recent power outage I realized that while all our main computers are laptops with battery power, the WiFi and modem are not. Cable service to the area continued working fine, but without power to my modem I couldn't get online.
All the guides and ratings I've seen for UPSs are for powering a PC. A modem and WiFi base consume significantly less power, does that mean that a UPS rated at 20 minutes for a computer would power the network equipment much longer?
I would like to find out how to select a good UPS for my network hardware. How will I know which one fits my needs?
Answer
Your two devices probably consume about 10 watts each, so your assumption that a UPS could keep the modem and wireless router powered longer than a PC is true. In one hour your two devices would consume about 20 Watt-hours. So a small 200 Watt UPS would optimistically backup these devices for a whole work day.
The problem with a low-wattage UPS is that they tend to be built cheaply. The electrical output is typically not a sine wave like the power from the utility company, but rather a square wave which may introduce electrical noise in some devices. The switch-over time from loss of main power to providing power from the battery can be another weak point. The best (and expensive) UPSes have zero switch-over lag by always supplying the power from the batteries.
UPS typically use one or more sealed lead-acid battery, which last for 3 to 5 years. I just had to replace a battery the other day after 4.5 years life.
BTW do not test the UPS by simply unplugging the UPS! That would also remove the (electrical) ground connection and create a shock hazard. If you want to test the backup capability of a UPS (after the internal battery has been fully charged up), have a power strip (with a switch) installed between the wall outlet and the UPS. Test the UPS by switching off at the power strip, which will maintain the electrical ground connection.
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