Don't worry about the battery inside the sounder at this stage,remember to fully test the system when you have replaced the control panels battery.
All professional quality alarm systems must have a back-up battery in order to maintain the system in the event of a mains power failure. The battery is usually fitted within the control panel. The most common type of backup battery is the rechargeable (12v nominal) lead/acid type. These are usually valve-regulated sealed units, and can thus fitted in any physical orientation, although it is safer to fit them upright where possible. The battery is recharged from a fuse-protected charging circuit in the control panel.
Battery life is approximately 5 years, but the battery should be tested annually. The simplest way to test the battery without test equipment is to disconnect the mains supply and ensure that the battery maintains the alarm system in unset mode. NB: If the Battery in the system is known to be more than about 4 years old be wary using the above method especially on alarm systems over 10 years old or on low end systems sold by DIY stores as these may not be fitted with a Non-volatile Memory (NVM) or in some cases the NVM may be corrupted. Some Control Panels indicate when the battery voltage falls below a certain value and thus needs replacing.
Battery Capacity
Battery capacity is measured in Ampere hours (Ah), where 1Ah will supply 1 Amp for 1 hour. For example a battery rated at 2.1Ah will maintain a system using 1 Amp for 2.1 hours. In general the largest capacity battery that can be used should be fitted - this is usually determined by the physical size of the control panel. Control panels described as compact will only accept 2.1Ah batteries whereas large-cased panels will accept any battery up to 7.0Ah and in some cases up to 2 x 7.0Ah batteries can be fitted.
European standards recommend that the battery should maintain the system in standby (unset) mode for 12 hours. To determine the battery size required for the system, the power used by the system in standby mode should be calculated and then multiplied by 12 to give the size of battery required. For example, consider the following system with typical standby currents.
Control Panel 50mA
External Sounder 50mA
4 x PIRs (15mA ea) 60mA
Total Power (standby) 160nA
Battery required for 12 hours standby = 12 x 160 = 1920mAh = 1.92Ah
Hence a 2.1Ah battery will suffice, and as such any size control panel could be used.
Obviouly, the addition of extra powered detectors or external sounders would then require a larger battery and hence a larger panel.
Battery Replacement
WARNING
THE MAINS SUPPLY TO THE CONTROL PANEL MUST BE ISOLATED BEFORE OPENING THE ALARM CONTROL PANEL
NB: On older control panels (not fitted with a Non-volatile Memory [NVM] Chip), removing all the power (mains and battery) may result in the control panel reverting to its factory-set defaults, and it will thus require re-programming. If this is a possibility then it may be beneficial to use a qualified electrician to replace the battery. The installation manual will be required to re-program the system.
Disconnect the mains supply to the control panel - confirm that the power light extinguishes.
Remove the control panel cover - alarm will sound - enter the user code to silence the alarm.
Disconnect the leads from the battery.
Connect the new battery - observe polarity. Silence the alarm by entering the user code.
Refit the control panel cover.
Reset the control panel.
Restore the mains supply.
Note: the new battery may take several hours charging to reach its full capacity.
So in short the veritas will except up to a 7Ah (excluding the compact),battery to big for the compact :).
e manno, October 2013