Standby Batteries (and Test)

Removing the mains supply to the control box can cause problems. If the control unit battery (usually a FLOAT CHARGED 12 volt, sealed lead-acid unit or two 6 volt batteries wired in series) is low or weak, some older control units will revert to factory settings of all its facilities, including the operating code needed to set and unset the system. Most outside sounders will sound from 20 minutes to a number of hours, if not fitted with an integral cut-off timer, and will not stop! If you do not have the handbook-you are in trouble!

Change the control unit rechargeable battery after 5 years at the latest.

If you do not, you will only find out you have a problem if there is a power cut! The external sounder will probably start sounding, and your security code may not work. This event will inevitably occur at a weekend or public holiday, when finding an alarm engineer willing to attend is almost impossible. Another compelling reason to take out a maintenance contract on the system!

You should at least try to find out the factory default code, before you have a problem. The handbook for the control unit will also give the programming procedures for restoring all zone types and timer settings etc.

STANDBY BATTERY TEST

A standby battery in good condition should power an alarm system, without a mains supply for about 8 to 24 hours. When the mains supply is restored, the battery should recharge within 24 hours. The European standard will require a 24-hour standby facility.

Practically all stand-by batteries are of the sealed lead acid type. They are usually 12 volt, or 2 x 6 volt with a capacity of 1 to 6 ampere-hours. They do not take kindly to high current charging, or being left in a discharged state.

Do not charge with a standard lead acid battery charger-they will overheat, swell and maybe explode!

The charging voltage from the alarm control unit should be close to 13.8 volts. This will ensure that the battery will recharge, or float charge without problems.

A "Rule of thumb" Battery Test

Disconnecting the battery from the control unit and connecting a suitable car bulb across the battery contacts can make a rough test of battery condition. A 6 or 12 watt bulb at 12 volts will draw a current of 0.5 and 1 amp. If the battery can keep the bulbs properly lit for 5 minutes the battery is in at least a reasonable condition. DO NOT DO THIS TEST WITHOUT EYE PROTECTION AND KEEP WELL CLEAR OF THE BATTERY.

IMPORTANT WARNING

DO NOT SHORT OUT THE BATTERY TERMINALS, THEY CAN SUPPLY A VERY HIGH CURRENT. BE CAREFUL OF METAL WATCH STRAPS SHORTING THE TERMINALS.

THEY CAN RAPIDLY BECOME VERY HOT! REMOVING A RED HOT METAL WATCH STRAP IS A ONCE IN A LIFETIME EXPERIENCE!

Do not tamper with any system covered by a current maintenance contract.