EP3556 – 4 CELL 4.8V 3AH NI-MH SC 2+2 Emergency Lighting Battery, With a Higher Capacity For Greater Reliability

Other information for the EP3556

Cross referenced with other manufacturers part numbers:
4/1SCM3-C-C008F

Other Eaton alternatives that are stocked:

EP3514
4/1SC2-C-C008F

NIMH Batteries

NiMH (nickel-metal hydride) batteries are rechargeable power sources that use a hydrogen-absorbing alloy at the negative terminal and nickel oxide hydroxide at the positive terminal.

They offer higher energy density than older NiCd batteries and are more environmentally friendly, but they have a higher self-discharge rate than newer technologies like lithium-ion. NiMH batteries are commonly used in household electronics, cordless phones, and some hybrid vehicles.

How they work

During a discharge cycle, the negative electrode (metal hydride) releases stored hydrogen, and the positive electrode (nickel oxyhydroxide) absorbs hydroxide ions, generating electricity.

During a charge cycle, the process is reversed, with electrons flowing from the charger to the positive electrode and then to the negative electrode, storing energy.

Advantages

Higher capacity: Typically have two to three times the capacity of NiCd batteries.

Environmentally friendly: Contain fewer toxic elements than NiCd batteries, making them safer to dispose of and recycle.

Less prone to memory effect: Less sensitive to the memory effect than NiCd batteries.

Good performance: Can operate well at a wide range of temperatures and are efficient at high-rate discharges.

Disadvantages

Higher self-discharge: They lose their charge faster than some other battery types when not in use, though low self-discharge (LSD) versions are available.

Shorter lifespan: Generally have a shorter cycle life and lifespan compared to modern alternatives like lithium-ion batteries.

Susceptible to heat: High temperatures can degrade their performance and reduce their service life.

Lower energy density: Have lower energy density than lithium-ion batteries, limiting their use in high-performance or very compact devices.

Considerations for use

Voltage: The nominal voltage for a single NiMH cell is 1.2V, so for systems requiring higher voltages, multiple cells are connected in series. Always check the required voltage for your fixture.

Capacity (Ah): Check the amperage-hour (Ah) rating to ensure it meets the backup power needs of the lighting fixture.

Compatibility: NiMH batteries can often be used to replace NiCd batteries in existing electronics, as they are compatible with similar charging systems.

Maintenance: While they are low-maintenance, they are still rechargeable batteries and should be stored with a partial charge if not in use for a while.

https://data.energizer.com/pdfs/nickelmetalhydride_appman.pdf