Back UPS ES 750 chirps once and shuts down.

[droid714]

I have a Back UPS es 750 that has given me many years of problem free service. During that time, I have had to replace the battery a few times.

In February 2026, I replaced the battery and resumed normal, trouble free usage.

Then suddenly, in late May 2026, while I was sitting at my computer I herad a quick chirp from my unit and every thing shut down. I was able to power it back up and everything seemed normal.

The next day, the chirping and shutting down was practically constant. Sometimes it would start back up on it's own and sometimes it would not. There was never any log information in my Power Chute software. 

I tried the power off test and the hard reset to no avail. I crimped the battery connectors to ensure a tight connection. 

Then, for no apparent reason, it worked fine for about a week. Then today, it started failing intermittently again.

I know the battery is good, it measures 13.6 V. Right now, all I have plugged into it is a singlw low wattage LED lamp and it still fails.

Any ideas?

[Teken]

When the RBC is replaced the following action items must be completed in sequence. Keep in mind the unit should be (Brain Dead) reset three times before proceeding!

Date: The battery (RBC) installation date must be updated via Power Chute. Doing so resets internal counters and adjusts charging tables if applicable.

Self Test: Manually initiate a self test via Power Chute Software and let pass. Allow the RBC to return to 100% SOC (State of Charge).

Calibration: Manually initiate a battery calibration via Power Chute Software with a minimum of 30% connected load or higher. Once this procedure has completed allow the RBC to recharge 100% SOC. 

This procedure will help the system learn the current RBC Health / Capacity. This will allow the system to better reflect the true operational runtime on the LCD, Power Chute.

If Power Chute does not have a calibration option. Simply remove AC Mains from the wall outlet and allow the system to shutdown by itself.

NOTE: In the above scenario unplug the USB cable that runs Power Chute Software. Otherwise the system will prematurely shutdown the unit and negate the calibration process.

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