Low use ups - how often replace battery

[bob100]

I have a whole house backup generator. I use several be600m1 backups to cover the 30 seconds from the time the power goes out to the time the generator starts. Except for the occasional click from a power flicker, they just sit there waiting for an outage.

How often should I replace the batteries in them?

The standard internet answer is 3 to 5 years. The answer is useless as the batteries never discharge. Many anecdotal stories I read say they last longer under low use. Mine have just reached 5 years. The power chute software says they are in fine shape,

What is a realistic life span under this load? I will replace batteries when appear ready to go.

[Teken]

Perform a real world *Lights Out* event and disconnect the 120 VAC from the wall. Compare the actual runtime with the published APC runtime calculator.

If the runtime is half the stated operating state you can accept that or replace the battery cartridge / cell. If however performing the same test causes the UPS to immediately shut down / turn off.

Well, you know first hand the cells are expired and need to be replaced. 👍 Conducting a real world (lights out) test is one of the most important validation you can ever do. Keeping in mind every cell / cartridge only provides an estimated 260 full cycles! ☝️ So conducting a full cycle test must be balanced with usage, environment, and temperature.

Using a conductance tester that can measure the internal resistance of the cell is more accurate, less stressful on the cell, and provides consistent state of health of the cells. Using both (lights out & conductance meter) to validate a battery is healthy is the best industry standard.