“But my battery is basically Brand new !”

Since the first round of Eskom loadshedding in 2008, alarm companies, and gate automation companies all over South Africa have been hearing the above refrain. After all, alarm batteries last for minimum 3 years, dont they?

Typical lead acid alarm battery construction

BB_batconst

In fact, the life of the battery in your alarm system depends on a whole host of factors. Heat, overcharging, undercharging all hasten the end of your battery. Since this isn’t a technical article, i’ll stick to the factor which is the most dramatic, and the most current .(ok, little techie giggle there ¬†ūüėČ ¬†)

The rechargeable Sealed Lead Acid battery, or SLA fitted in your home alarm system or driveway gate motor is made up of plates, lead, and lead oxide with a 35% sulfuric acid and 65% water solution. Charging and discharging coats the plates with sulphur, and removes the sulphur from these plates. Throughout the life of your battery.
Until load shedding comes along.

Each time a SLS battery discharges completely, the plates inside corrode and little pieces break off. This is called¬†Deep discharging.¬†Most modern gate motors and computer UPS’s ( Uninterruptible Power Supplies) have built in circuitry to prevent its battery from discharging below a certain point. Generally alarm systems lack this protection. Security systems normally report, either visually or via a signal transmitted to a control station, that the mains power to your alarm system has been lost. And then you go and remedy the situation. Plug the alarm transformer back into the socket your domestic worker removed it from, or top up the prepaid electricity.

With Eskom’s load shedding programme, we unfortunately don’t have these¬†options.
Battery manufacturers estimate that 5 to 10 such deep discharges can occur before the battery sustains serious damage.
Of course this depends on the number of sensors and keypads drawing power from your alarm system battery, but the sad news is that yes, load shedding does send your alarm battery to an early grave, so be prepared to replace your battery much earlier than a few years of use. Depending on Eskoms schedule, perhaps after only a few months.