UPS starts on battery

[Dom_apc]

I have a Back-UPS RS1500 and replaced the battery around 5 years ago. The unit has been working just fine. I recently went out of town for a few days and turned the unit off. After I returned, the unit now starts up and goes directly to the battery. The circuit breaker is not tripped. I've tried different sensitivities, but nothing seems to work.

Also, this is running in a Mac system so I don't have Powerchute. The OS readout in Energy Saver is pretty basic and only says the battery is fine.

What can I try now?

[JonPro]

Hi @Dom_apc 

Apologies for the inconvenience this has caused.  Let me assist you with this, based on the description, the UPS fails to detect the input power source which could be caused by an internal component failure.

In a situation like this, we suggest adjusting the sensitivity of the UPS which you already did.  You can bring the UPS and plug it into a different place to rule out any voltage or frequency issues. 

You can also perform a logic reset on the UPS, if all of these steps wouldn't resolve the issue.  It is recommended that the US be replaced.

Please see the FAQ article below for our perusal.

How to Brain Dead a Back-UPS unit. (Full UPS Logic Reset) - FA158947