APC smart ups 750 says Battery Not connected

[Anonymous user]

The unit was manufactured 2010 in use since about that time, second battery was installed Jan 2016.

This morning I found the UPS beeping with the message : battery not connected on the panel.

Disconnected the unit, extracted and connected the batteries back - same message.

Batteries are slightly warmer then room temperature, measured as disconnected read 25.8V on my multimeter, in 15 minutes came to 26.09V. with the two elements at 13.03V, 13.05V

I am pretty sure there was no power outage last night.

Did the UPS gave up the ghost or should I consider replacing the batteries again (different message as I know).

Thanks! 

[BillP]

Hi Kamen,

You are right the typical alert to replace the battery is a Replace Battery display message with the Replace Battery LED on (depending if the model has LCD display / LEDs or both). However UPS units can also report battery disconnected in similar scenarios with weak/old batteries.

What is the UPS model number? Most 750VA UPS units will have a 24VDC battery, the expected float voltage for this would be 26-27V and will decrease slowly to 24V when the battery is under load. Considering you measured 25.8V on the battery right after disconnecting it, chances are high it's only the battery that requires replacement. 

[Anonymous user · Accepted solution]

Thanks Szabi, 

Indeed, seems you are right, we found a new battery lying around in the office. Replacing the old one fixed it. 

It's nice when some of your colleagues don't use their UPSs replacement batteries ..

Single problem - due to that failure all my virtual machines died on my ESXi  have to rebuild them. Ah well, I remember flashing firmware once and that particular UPS saved me, so something for something.

Cheers!