AT&T Central Controller Battery

Indication of trouble:  You probably need a new lead-acid battery in your Central Controller if your system gives you trouble beeps (twice every 40 seconds), displays "CC" and the "Low Battery"  light is on.  

Comments.  Note that we would usually install the replacement lead-acid battery and take away the old one.  These must be recycled.  It is illegal to discard them in household trash.

While we are there, we usually do a number of other tests and spot-checks that are very important, including especially, cleaning the smoke detector(s).  Therefore, since the Central Controller battery typically last 2-1/2 to 4-1/2  years, it's best to have us do this job, unless you are able and have the time to do all of the other other system checks.  

General Information.  These batteries are permanently sealed and use a jelly type electrolyte.  They are rechargeable.  If your utility power goes out, the system switches over to the standby battery automatically.  They recharge during the 24 hours after power is restored.  The number of hours that the system can continue to operate on the battery depends primarily on the size of the battery, its condition and state of charge at the beginning of the outage, and the overall system size.  

Many of our systems will report a "Loss of AC Power" to the Central Station, typically an hour or so later.  However, most of the AT&T 8000 systems Do Not.  After a few hours of operation on the battery, the voltage gets down to a preset level where the system will report a "Low Battery."  (This is different from a "Transmitter Low Battery" signal.)  Because there are several types of communicator modules used in the AT&T 8000 system, many of these systems Do Not report "System Low Battery."  If notification of these two supervisory conditions is important to you, call us to discuss it.  

These batteries are not widely available at consumer outlets, but they can be found if you know exactly what you need and if you know where to shop.  Because this is a critical component of your system (and I'm not ashamed to say it's also an important source of income to us), we prefer to supply the replacement battery.  

They are reasonably safe for a consumer to handle, but on the other hand, you can still get in trouble or injure yourself with one of these if you don't know what you're doing.  

Warnings

My most urgent safety precaution is "Don't drop a battery on your foot."

Next, be careful not to get the wires on backwards.  The red wire goes only on the red terminal.  I'm not saying where the black wire goes.  If you need to ask, you need us to do the job.

Procedure

Put the system on "No Action" at the Central Station before you touch anything.

Open the Central Controller.  The battery is on the bottom tray, to the left.  It is about the size of half a brick.  It will have a red and a black wire coming from it.  

Check the connections before you condemn the battery.  Once in a while we find that a wire has simply come off the battery due to vibration or pressure from closing the case against it.  Loose lugs, errant hands and feeble minds are other known causes.  (Who, me?")

Note that the battery gets progressively weaker as it ages due to electrolyte evaporation caused by constant "float charging."   Look at the install date that was written on it by the installer.  The 4.0 through 5.0 amp hour battery will usually last about three or four years.  The 7.0 amp hour battery may last longer, but I'm not saying exactly how much longer.  If the battery is more than five years old, just get a new one, don't even bother with any further tests.

If you see chalky corrosion on either of the battery terminals, that's really bad.  The cell connections inside the sealed battery case may be too weakened to sustain the current when required, even though the cells might be fine.  Get a new battery for sure, and also get new pigtail wires if the old ones can't be cleaned and reused.

If the battery case is cracked or bulging, it's over.  Just get a new one.

If the battery is noticeably warm to the touch (say, 120 degrees or more), that's bad.  [Don't be confused, note that the plug-in power transformer is normally warm.]  It suggests a possible shorted cell.  It would usually be hottest around that cell itself.  (There are six cells inside a 12-volt battery.)  There could also be a device somewhere in the system that is shorted.   

This could be a casualty in progress, call us at once. 

If the battery passes all the above spot checks, disconnect the wires and take it out.  Without clunking yourself in the head, hold it near your ear and give it a shake (the battery, that is).  If it rattles (the battery, that is), the electrolyte is dried out.  You need a new one.

Use a voltmeter to check the voltage on the battery while nothing else is connected to it.  Assuming the system has had AC power for the few hours just prior to this incident, it should be greater than 12.6 volts.  If it's 10.5 to 11.1 volts, it probably has a shorted cell or is discharged by a lack of AC power.  If it's any other voltage under 12.0 volts, it may be discharged by a lack of AC power.   

The battery needs to be able to deliver its power to the system.  Even though you have the correct terminal voltage, the battery could still be bad if the internal cell connections are corroded or the electrolyte inside is dried out.  If a battery has passed all of the above checks, we then usually conduct a brief load test.  Such a test should only be undertaken by a person who is skilled with electrical things.  Having said that, you can use some alligator wires to light up a spare tail light bulb for a couple of seconds.  It should be nice and bright.

Many of our systems have two or more main batteries in them, but only one battery will fit into a standard AT&T 8000 Central Controller.  Call us, we can schedule a service visit.  We don't recommend it for most system owners, but if you prefer, we're agreeable to ship you a fresh one at a nominal cost.  If you are one of our subscribers, we'll also assist you for free by phone to get it installed.  You will need to give us the part number off the old one so we can send the correct size.  (Most are 4.0 to 5.0 amp-hours.  Some cabinets have been modified to accept a 7.2 amp-hour battery.)  You need to be somewhat handy to do this particular job, and you will need a screwdriver with a 1/4-inch flat blade to open the Central Controller cabinet.  Safety glasses and steel toed shoes are recommended when working with batteries of this type.