Central Battery Emergency Lighting Systems
A Central Battery System (CBS) provides emergency power from a single, centralized source to multiple emergency luminaires. This contrasts with self-contained systems, where each fitting has its own battery. Central systems are ideal for large buildings or complex installations where centralized monitoring, control, and battery maintenance are preferred.
How Central Battery Systems Work
- The central battery unit powers all emergency lights via dedicated wiring.
- Under normal conditions, the system monitors power and keeps the batteries charged.
- On mains failure, the central battery activates and supplies power to all connected luminaires instantly.
- Systems may supply AC or DC power depending on the luminaires used and system design.
Types of Central Battery Systems
| Type | Description |
|---|---|
| AC/AC | Outputs alternating current. Allows use of standard mains luminaires. Offers high light levels and greater flexibility. |
| AC/DC | Outputs direct current. Requires DC-compatible emergency fittings. Common in purpose-built systems. |
Applications
Central battery systems are especially suitable for large or high-occupancy buildings where consistent, reliable emergency lighting is essential:
- Hospitals & healthcare environments
- Universities & schools
- Large office complexes
- Shopping centres & commercial buildings
- Warehouses & industrial sites
Advantages of Central Battery Systems
- ✅ Centralized Maintenance: Easier to monitor and test a single battery bank rather than individual luminaires.
- ✅ Extended Battery Life: Batteries typically last 5–10 years depending on the type (vs 3–5 years in self-contained).
- ✅ Higher Output: Supports greater lighting performance and larger numbers of fittings.
- ✅ Improved Monitoring: Many systems offer fault reporting, remote diagnostics, and testing automation.
- ✅ Cleaner Aesthetics: Luminaires can be sleeker since they don’t require onboard batteries.
Disadvantages
- ❌ Higher Initial Cost: Installation involves more infrastructure (cabling, central unit, space allocation).
- ❌ Single Point of Failure: If the central battery fails, the entire system could be affected—redundancy is recommended.
- ❌ Complex Installation: Requires specialist design and electrical planning.
- ❌ Space Requirements: Battery rooms or cabinets may be needed to house central units safely.
Maintenance & Testing Requirements
(As per BS 5266-1 and BS EN 50171)
| Check/Test | Frequency | Details |
|---|---|---|
| Visual Inspection | Daily (manual systems) | Check control panels, LEDs, ventilation, and system status. |
| Functional Test | Monthly | Simulate power failure to confirm emergency lights activate. |
| Full Duration Test | Annually | Lights must remain illuminated for full rated time (usually 3 hours). |
| Battery Inspection | Quarterly | Check voltage, connections, and signs of degradation. |
| Battery Replacement | 5–10 years | Varies based on battery type and manufacturer. Replace proactively, not only on failure. |
Battery Types & Lifespans
| Battery Type | Typical Lifespan |
|---|---|
| Vented Lead-Acid | 5–10 years |
| Sealed Lead-Acid (VRLA) | 5–7 years |
| Nickel-Cadmium (NiCd) | 7–10 years |
| Lithium-Ion (where used) | Up to 10+ years |
🔋 Regular checks on charge/discharge cycles and ambient temperature help prolong battery life.
Use Case Scenarios
| Environment | Why CBS is Ideal |
|---|---|
| Hospitals | Consistent lighting across wards and corridors. |
| Shopping Centres | Centralized control over a large number of lights. |
| Schools & Colleges | Simplifies routine testing across campus buildings. |
| Multi-Storey Offices | Minimizes battery clutter across floors. |