RS 1200 Running in Battery Mode Only

[BillP]

We have 3 RS 1200 units, two are working fine. Batteries were replaced in all 3 in fall 2010.

Today, the third unit switched to battery power and ran until battery ran out. It emitted 4 beeps every 30 seconds. The "Replace Battery" light is NOT on.

Technical information on the problem unit (according to PowerChute):

Model: Back-UPS RS 1200
Serial Number: JB0618020782
Firmware: 8.g1. D

We have tried plugging the unit into multiple AC jacks in multiple rooms, that are known to have good AC power. This does not help, the unit always run in battery-power mode.

I downloaded and installed PowerChute Personal Edition for Windows XP. After installation, first run of this program claimed that the battery "is more than 3 years old". This is not true, the battery was replaced last fall.

PowerChute:

- "Run Self Test" option: reports "Cannot complete self-test as there is no battery backup connected"
- "Voltage" page: UPS is set to intervene if voltage goes over 132 volts, or under 97 volts. "The current voltage" is shown varying between 91 and 96 volts. Although we don't have a voltmeter to check, there's no way the wall AC voltage is actually that low
- "Current Status" page: agrees that input voltage is in the low 90s

What is the most likely cause of this error? Could it be caused by a bad battery pack, or is it likely that some other part of the UPS has failed? Any ideas or comments appreciated.

[BillP · Accepted solution]

Good day Al,

If you do have a domestic UPS model that runs on 120V AC and was previously working and all of a sudden it stopped, most likely that one of the components failed. As per your post, you made sure that the UPS has been tried on known good working outlets and I presumed that the other UPSs that you have there has been tried on the same outlets as well.

If the other UPSs are working fine and this particular UPS detects that there is around ~90V AC that is being fed to it, the voltage sensor could be damaged already. If let's say the UPS was reading around ~100V or higher, we could try changing the sensitivity and transfer voltages.

On PCPE, if I am not mistaken there is a battery icon that you can click and it will ask you if you would like to change the battery replacement date to the current system date of your PC.

[BillP]

Thanks for your comments. I've since confirmed that the input AC is close to 120V but that UPS reports in the low 90s, looks like its voltage sensor is not working properly.

Just for grins I removed the upper front panel and blew out the upper interior of the unit with a compressed gas duster. There wasn't much dust considering over 4 years' continuous use. That had no effect on the problem.

I think I have to disagree with your idea of playing with the unit's voltage sensitivity if it had happened to read ~100V. The whole reason to have a UPS is to improve reliability. Using settings like that to try to compensate for a wonky sensor would just come back to bite you, likely in the very near future.

So, off to get a new UPS 🙂

[BillP]

You are very much welcome and it is okay if you do not want to change the sensitivity. I've put it on my post thinking that there might be other posters who might be experiencing some power problems, this might help them.

If you are planning to get a new UPS, you can use this UPS and go after our TradeUPS program. Our TradeUPS program offers you new UPS models on a discounted price. To know more, feel free to call our APC Tech Support Hotline at 800-800-4272.