Is it dangerous or not advisable to change the UPS battery while it is plugged in? We have an APC Smart-UPS 1500 and we need to replace its battery. I have the new battery but the UPS powers a few machines that I would rather not turn off for the replacement procedure.

Would something bad happen if I just replace it while it's still plugged in and powered on?

  • 9
    Check the manual. Some UPSes support hot-swap, some don't.
    – womble
    Jul 2, 2012 at 14:27
  • @womble - thanks, the manual that was in the replacement battery box did not mention anything about power. The instructions only show how to open the battery compartment etc. That's why I thought the "real" UPS manual would not contain the info as well. Obviously I'm glad to be proven wrong :)
    – Siim K
    Jul 2, 2012 at 14:45

4 Answers 4


According to the manual:

Replacing the Battery Module

This UPS has an easy to replace, hot-swappable battery module. Replacement is a safe procedure, isolated from electrical hazards. You may leave the UPS and connected equipment on for this proce- dure.

  • 4
    I've hot swapped the batteries on several smartUPS models including the 1500 without any problems.
    – Rex
    Jul 2, 2012 at 15:25

The Smart-UPS 1500 battery is hot-swappable. You do not need to unplug or power down the UPS before changing the battery.

Of course, it is essential to refer to the product documentation and take all appropriate measures to protect yourself from the shock/electrocution hazards associated with live batteries and charging equipment. Under the right (wrong) circumstances, even a 12-volt lead acid battery can deliver a fatal shock.


I "Hot Swapped" 3 APC Smart UPS 1500 batteries at three different power plants here in southern California. These UPS systems are used to power the CAISO RIG (California Independent System Operator Remote Intelligent Gateway). It is a critical system for our electric power grid in the State of California.It took me less than ten minutes to perform this task! This is the first time I ever had to change a battery in a UPS system. The tools I used were just one Phillips screw driver


Apparently most APC UPS's, not just "smart" ones, support battery hot swapping.

The manual for the Back-UPS ES 525 advises:

Do not replace the battery when the UPS is On Battery (amber indicator is lit).

-- but that dumb warning is obviously applicable to "smart" UPS's as well.

The manual proceeds telling:

NOTE: Small sparks may occur during battery connection. This is normal.

-- can't remember if sparks fly during an offline UPS battery connection.

Not the answer you're looking for? Browse other questions tagged or ask your own question.