SYSTEM DESIGN

BATTERYTYPE BATTERYTYPE Cooper Lighting and Security offer a choice of five different batterytypes:•Cock regulated lead acid (10 year design life)•Valve regulated lead acid (3-5 year design life)•Vented nickel-cadmium•High performance plante lead acid•Flat plate lead acid Each battery type has specific characteristics. In order to assist withthe choice of battery, full details of the characteristics and benefitscan be found in the Loadstar and Static Industrial inverter System productpages. The table below (fig. 2) provides a comparative guide tothese characteristicsThe most popular battery type is valve regulated lead acid with a10 year design life. This type of battery is used on approximately 90% of projects due to its competitive cost, good lifecharacteristics, ease of maintenance and compact size.
Fig. 2 Comparison of Battery Characteristics CharacteristicsValve RegulatedValve RegulatedVentedHigh PerformanceFlat plateLead Acid (10 year life)Lead Acid (3-5 year life)Nickel CadmiumPlante Lead AcidLead acid Expected Life

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Capital Cost Maintenance Resistance to damage & abuse Through Life costs BATTERYROOMVENTILATION Vented professional batteries, such as nickel cadmium, plante and flat platelead acid emit potentially explosive gases under chargeconditions. Therefore it is important when selecting rooms for emergency lighting central battery systems with these types ofbattery, to calculate the amount of ventilation required.The required number of air changes per hour (A) is given by thefollowing formula: A =0.045 x N x IV Where:N=Number of cells in the batteryV=Volume of room in cubic metres I=Charge rate in AmperesThis formula will give the number of air changes per hour requiredduring boost charge conditions. On float charge (systems are onfloat charge for most of their service life), the amount of gasemitted is approximately 1.5% of that liberated whilst on boostcharge and under most circumstances this will be dissipated bynatural ventilation, and will not present a hazard. However, we recommend that the boost charge condition is allowed for at thedesign stage to ensure the appropriate decision on ventilationrequirements is made.Although Valve Regulated Lead-Acid Batteries require littleventilation under normal operating conditions, it is good practice toapply the formula to calculate the number of air changes requiredto achieve minimum risk under battery fault or failure conditions.
Emergency - Central Battery Systems