Why are online UPS so expensive?
"The basic technology of the online UPS is the same as in a standby or line-interactive UPS. However it typically costs much more, due to it having a much greater current AC-to-DC battery-charger/rectifier, and with the rectifier and inverter designed to run continuously with improved cooling systems.
How many years will UPS battery last?
Cause / Resolution: Most APC batteries should last three to five years. There are many factors which affect Battery life including environment and number of discharges.