DSC PC1550 Trouble: Low battery


Old 11-19-19, 11:21 AM
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Join Date: Jan 2014
Location: USA near Boston, MA
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DSC PC1550 Trouble: Low battery

I am trying to determine what to do about a low battery trouble alert on my DSC PC1550 system.

Last Friday afternoon I heard a repeating 3 beep signal from my control panel. Upon investigation I determined that it was due to a low battery trouble alert. The battery was last replaced in April 2015 but still measured 13.6 volts (disconnected). I think it replaced the original battery installed in 1996.

My alarm company technician was not in the office to help me trouble shoot and I was planning to be away for the weekend, so I purchased a new battery.

Before installing the new battery I performed a battery/bell test. When I did that the trouble signal cleared, so I did not install the new battery.

The system operated with no problem throughout the weekend.

Today I measured 13.8 V on the battery leads (disconnected), to make sure the charger is working.

Should I:

A. Install the new battery?

B. Keep the new battery as a spare due to the age of the existing battery? (How much shelf life could I expect?)

C. Return the battery?

Any thoughts about why a random low battery trouble would occur on an apparently good battery and charger? We have not had any recent power outages. Two additional smoke detectors and an EOL relay were added to the fire loop in 2013.

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Old 11-19-19, 02:57 PM
Join Date: Aug 2017
Location: United States
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If it was last replaced in 2015, go ahead and put the new one in.
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Old 11-19-19, 05:55 PM
Join Date: Nov 2009
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Perljammer is right: It's time to replace the battery.

It's not unusual for a weak battery to meter at ~13.6V immediately after it's taken off the panel. A voltage reading at that time is not an indication of how much charge (in terms of Ah) the battery can hold.

After you replace the battery, you might want to hang onto the old battery and test the voltage over the next several days. You'll probably find the voltage drops a few tenths of a volt each day until it stabilizes after about 5 days, probably at somewhere between 12.5V and 12.8V (just a guess). It still has usable life for other applications, but it isn't holding a full charge anymore is isn't reliable to keep your system operating in the event of an extended power failure.
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Old 11-20-19, 01:35 PM
Join Date: Sep 2015
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And it won't hurt to mark the new battery "Replace No Later Than Month/Year". 3 maybe 4 years is what you can reasonably expect from a Sealed Lead Acid battery.
The battery is like most 90 year old men looking at an attractive woman; the want want may be there (voltage), but the ability is gone.
2john02458 voted this post useful.
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