Yuasa 2DH4-0L4 2.4V 4Ah NiCd Emergency Lighting Battery, High Temperature D Cell Stick Pack with Leads

Overview

An emergency light keeps an escape route lit when the mains fails, running from its own rechargeable battery until the power returns. This pack is that battery for luminaires designed to take a 2.4 V NiCd stick of D cells.

It comes from the YU-Lite nickel cadmium range, made for industrial applications such as emergency lighting.

How it works

• Nickel cadmium: NiCd cells store charge chemically and take repeated charging well, which suits a battery that is kept topped up for years and called on only in a power cut.
• Cell construction: the cells use foamed nickel technology and a 3D mesh structure, a design aimed at higher capacity in a smaller can.
• High temperature cells: the H in the code marks the high temperature D cell, the version tested to ICEL 1010.

What the figures mean in practice

• 4000 mAh at the 5-hour rate: capacity is measured over a 5-hour discharge. The rated duration of the light also depends on its lamp and electronics, not on the battery alone.
• 2.4 V from 2 cells: the cells are joined to give 2.4 V nominal, so the pack only suits a luminaire designed for that voltage.

Installing it

• Match the pack: as a rule, replace like with like: same voltage, chemistry, cell count, pack style and connection. A different shape may not sit in the battery compartment.
• Connections: note the polarity of the old battery's connection before removing it, and keep the leads clear of hot parts.
• After fitting: in most emergency lights a new NiCd battery needs a full charge before a duration test gives a true result.

Planning your system

The job also needs a record of tests. A monthly function test and an annual full-duration test are the usual routine, and the emergency light testing guide sets out the steps.

For where emergency lighting is needed and how long it must run, read the emergency lighting regulations guide.

Test switches, legend plates and spares sit with the emergency lighting accessories, while other specialist batteries have their own range. The wider range of Yuasa batteries covers sealed lead acid blocks for alarm and standby use.

Standards and ratings explained

• ICEL 1010: ICEL is the UK industry committee for emergency lighting, and its scheme numbered 1010 is the test applied to the high temperature versions of these cells.
• Maintenance free: there is nothing to top up or service on the cells themselves, but the light still needs its regular tests.