Another case of won't work with new batteries--Back-UPS NS 1250 LCD

[BillP]

I have a Back-UPS NS 1250 LCD that is several years old. The batteries were shot so I replaced them with new Werker batteries, but it will not run on batteries for more than 2 minutes. The UPS passes all self tests and shows the batteries fully charged (on both the LCD and via PowerChute) after several hours. I did select "Replace Battery Date" in PowerChute. With a 30% load, it goes from full charge to no charge in only 2 minutes and shuts down. When connected back to power, it takes several hours to recharge again.

I have tried the manual recalibration technique several times--no change. Because it has no serial port (USB only), I cannot try the serial-based recalibration techniques.

Am I missing something? Is there some kinds of tests I can run to see what it might be doing or not doing (I do have voltmeters/scopes)? It there another way to accomplish the recalibration via a USB port?

Edit: voltage measured at the battery leads with the batteries disconnected is 27v.

Thanks in advance.

Message was edited by: JeffinMD

Message was edited by: JeffinMD

[BillP]

As I'm sure you know, we don't recommend using 3rd party batteries although many customers have and they usually work. Besides voltage, what other specs do these batteries have? What about AMP hours

[BillP]

The replacement batteries are WKA12-8F2 12V 8Ah, slightly smaller amperage than the originals which were 9 Ah. I also replaced the batteries in Back-UPS XS 1300LCD at the same time with the same batteries and they work fine.

The OEM batteries in the 1250 were Center Power Tech 1290
The OEM batteries in the 1300 were B.B Battery HR1234W

Thanks.

[BillP · Accepted solution]

SOLVED--one of the new batteries was defective

I checked the voltage of each battery--more than 1 volt difference--not expected. I took the batteries back to BatteriesPlus, and they did a load test on each. The one battery with lower voltage did not pass the test. They handed me two new batteries and the UPS is now functioning correctly.