Secware_Tech6 Posted April 23, 2020 Share Posted April 23, 2020 We get this question in support quite a lot. A Panel doesnt come with a battery as it needs to be sized to suit the demand of the system. Plus you need to consider recharge time and battery recharge load. Its never best practice to load a panel or power supply up to its maximum. Its like driving at maximum speed of the vehicle everywhere or having the music at full volume all the time. EN norms (the current UK standard for Intruder Alarms is EN50131 There are differing requirements for standby at Grade 1,2,3 and 4. Grade 2 and 3 systems are the majority of professional systems installed in the UK. Grade 2 requires a 12 hour standby time. Grade 3 24 hours (unless signalling AC fail to the ARC) I would always advise a tolerance for battery age and never use really cheap batteries. Quality batteries are essential. Once you have either calculated your standby current or checked with a meter that will give you a reading. We also need to calculate / measure Alarm current. If we assume a few readings for a typical system. Control Panel, 1 x Keypad, 1 x External Sounder, 1 x Internal sounder, 4 x PIR detectors, 2 x Vibration and a door contact. Lets assume a 380mA standby current. This gives us a standby current of 380mA per hour. Lets also assume an alarm current of 800mA. Most quality control panels are going to be rated at 1A min total current. As we have a limit of 15m Bell time under EN 50131 we can safely use half of the 800mA Alarm current (30 mins = 400mA) so 380mA x 12 (hours) = 4560 mA total current Lets add the 400mA of alarm current in (30 minutes of the 800mA per hour in alarm) gives us a total required for 12 hours of standy plus 30 mins of alarm of 4960 mA As batteries are sized in A/h (Amps per hour) we know we need a minimum of 5A/h battery Now id add a 10% age factor. The battery is only going to give its stated rating for a period of time. The older the battery the lower this output will be. That is why we should all be changing batteries at the latest every 5 years. Some will fail sooner or wont give the output required to meet the 12 hr standby requirement, so will need replacing sooner. so back to the maths, 4960 mA + 10% = 5456 mA 5456 mA or 5.5Amps The closest 12v alarm battery is a 7Amp unit Its a little more complicated as standby battery ratings are calculated on a 24 hour discharge not 12 hours. ie you cant put a 7A load on a 7A/h battery and expect it to last an hour. Also as a lead acid battery discharges its voltage drops. This will eventually become too low (problem will start to occur below 10.8v) and crashes etc will happen. Now you can see why those picking batteries on cost (using a 1.2 A/h) or just whatever fits isnt the best way to go! Quote Link to comment Share on other sites More sharing options...
chalky Posted October 22 Share Posted October 22 How often do current reading be done on a intruder alarm Quote Link to comment Share on other sites More sharing options...
Secware_Tech6 Posted October 23 Author Share Posted October 23 Should be taken on service and any works Quote Link to comment Share on other sites More sharing options...
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