Two backup batteries in my system?

[walter]

My ADT Safewatch 3000EN system has two big lead-acid backup batteries type
ca 1240, instead of just one backup battery! I understand this system is
similar to the Vista 15P.

I cancelled my monitoring contract with ADT and I am now on my own. The
system is about 4 years old, all hardwired. I thought of changing the system
backup battery preemptively. Then I found two identical big batteries in the
panel. It also has two wall wart transformers, both for 16.5V AC.

Battery leads (red and black) go from battery A into the Main Circuit Board
without terminals. The leads from Battery B go to (come from) a small
sub-panel marked Altronix AL 624 Power Supply/Charger. The two batteries do
not seem to be interconnected (such as being in series or parallel).

What is the second battery for and how do I replace both batteries?

http://img854.imageshack.us/img854/87/1000871.jpg
http://img402.imageshack.us/img402/2883/1000874d.jpg

Thanks for any input.

 

[Bob La Londe]

An AL 624 is a 1 amp power supply board (at 12V). Probably added because
the load of all the stuff on your system kept blowing fuses with just the
onboard power supply. If changing batteries change both. Also the PS has
no battery monitoring capability so you should date your batteries and
change them at regular intervals. Three (3) years as long as you have no
power issues used to be a good interval, but I have had a lot of Solex and
DSC (probably the same crap battery) fail in a year to a year and a half.
If you go with a top brand name like Yuasa then three years should still be
a good never a problem interval.

 

[Bob La Londe]

Battery going to big (main) circuit board is the security panel
battery. Other battery (Altronix) is for secondary power, probably
used to power motion detectors or such. Take info to batteries plus
or Google/order online. Disconnect leads. Reconnect. Voila!

Jewellfish

Not familiar with panel, but some may require full power cycle to reset
trouble displays then reset time and date. Op said preemptive so if he is
quick no trouble display should appear.