When an emergency lighting battery fails, it can be hard to know exactly what replacement is needed.
Sometimes, choosing a battery with the same voltage might seem sufficient — but in reality, it’s not always that simple.

Common types include:
Ni-Cd (Nickel Cadmium); NiMH (Nickel Metal Hydride); Li-ion

These are not interchangeable unless the control gear is designed for it.

Typical voltages include: 3.6V; 4.8V; 6.0V
Voltage must match exactly unless advised otherwise by a specialist.

Capacity determines how long the luminaire will operate in emergency mode.

The replacement battery must meet or exceed the original while remaining compatible.

Bigger is not always better if the charger is not designed for it.

Length; Diameter; Stick vs block configuration.

Older luminaires often have very limited space, especially bulkheads and downlights.

JST; Molex; Flying leads; Polarity orientation.

A correct battery with the wrong connector still won’t work safely.

The number of cells affects: Voltage; Charging profile; Heat generation.

This is critical when substituting batteries in older fittings.

1-hour vs 3-hour systems.
Regulatory and site requirements.
A replacement must maintain the required emergency duration to remain compliant.

Emergency Batteries