Re: Ademco 50P - Unable To Disarm

[Frank Olson <Use_the_email_links@xxxxxxxxxxxxxxxxxxxxxx>]

Robert L Bass (the "Putzmeister") wrote:

> I always did my battery calcs as follows:
>
> 1.  Add up mA ratings of all devices that will be operational during an
> alarm condition.  Deduct the drain for 1/4 hour of alarm sounding from the
> available Amp-Hours.
>
> 2.  Add up mA ratings of only those devices which run when the system is not
> in an alarm state.  Divide into the remaining AmpHours.
>
> By calculating the current drawn in an alarm state first you allow the
> system to run 24 hours (72 hours for some facilities) and still have enough
> juice to sound the alarm for fifteen minutes.
>
> I don't recall if that's actually required but it's the way I learned to do
> it.  I never had a submittal turned down for battery calcs so I guess the
> inspectors like it that way.  I've tried a few Excel battery calc
> spreadsheets over the years and though they're quicker than using a hand
> calculator they tend to be cumbersome and none of them cover all of the
> different types of hardware you might use on any given job.
>


We aren't talking "battery calcs", and your method doesn't address the
issue (which is the maximum allowable current draw from the auxiliary
power supply).  You can have correctly sized batteries for the
application but can still exceed the maximum allowable current draw.  It
leaves little doubt in my mind that many of the installations you've
involved yourself with are compromised using the method you're
advocating here.  The OP provides us another classic reason why any
DIY'er should employ a local industry professional to check his work
before powering up the system.  Spending "two hours on the phone
teaching someone how to install an alarm system" just doesn't cut it.
One small comfort, he will have the right size battery for the job
though (that's *if* your supplier ships the correct unit).

Frank Olson
http://www.yoursecuritysource.com