Nickel Battery Technologies
Nickel-Cadmium & Nickel-MetalHydride

Nickel based batteries are available in various battery chemistries. Each battery pack system offers unique advantages but none provide a fully satisfactory solution. Here at Epec, we focus on the 2 most popular chemistry's.

Nickel Cadmium (NiCad)

The nickel-cadmium battery (commonly abbreviated NiCd or NiCad) is a type of rechargeable battery using nickel oxide hydroxide and metallic cadmium as electrodes. The abbreviation NiCad is a registered trademark of SAFT Corporation, although this brand name is commonly used to describe all nickel-cadmium batteries. The abbreviation NiCd is derived from the chemical symbols of nickel (Ni) and cadmium (Cd). There are two types of NiCd batteries: sealed and vented.


  • Low internal resistance
  • High rate charge and discharge rates are possible
  • Up to 10C discharge rates for short periods typical
  • Flat discharge characteristic (but falls off rapidly at the end of the cycle)
  • Tolerates deep discharges - can be deep cycled
  • Wide temperature range (Up to 70°C)

NiCad Battery Pack for Commercial Lighting Application
NiCad Battery Pack for Commercial Lighting Application


  • Susceptibility to memory effect
  • NiCad batteries are also prone to damage by overcharging
  • Environmental Concerns of Cadmium

Nickel-MetalHydride (NiMH)

A Nickel-Metal Hydride cell, abbreviated NiMH, is a type of secondary electrochemical cell that uses a hydrogen-absorbing alloy for the negative electrode instead of cadmium. As in NiCd cells, the positive electrode is nickel oxyhydroxide (NiOOH). A NiMH cell can have two to three times the capacity of an equivalent size nickel-cadmium battery. However, compared to the lithium-ion cell, the volumetric energy density is lower and self-discharge is higher.

Useful discharge capacity is a decreasing function of the discharge rate, but up to a rate of around 1×C (full discharge in one hour) it does not differ significantly from the nominal capacity.

The specific energy density for NiMH material is approximately 70 W•h/kg (250 kJ/kg), with a volumetric energy density of about 300 W•h/L (360 MJ/m3).

Ni-MH Battery Pack for a Medical Device
Ni-MH Battery Pack for a Medical Device


  • High energy density (W/kg), about 50% better than Nicads, but only about 60% of Lithium ion
  • Low internal impedance
  • Typical cycle life is 3000 cycles
  • Can be deep cycled. (80% to 100% DOD)
  • Robust - NiMH batteries also tolerate over charge and over discharge conditions and this simplifies the battery management requirements
  • Flat discharge characteristic (but falls off rapidly at the end of the cycle)
  • Wide operating temperature range
  • Environmentally friendly (No Cadmium, Mercury or Lead)


  • High self-discharge rate
  • Suffers from memory effect though not as pronounced as with NiCad batteries
  • Battery deteriorates during long time storage. This problem can be solved by charging and discharging the battery several times before reuse. This reconditioning also serves to overcome the problems of the "memory" effect
  • Cells must incorporate safety vents to protect the cell in case of gas generation
  • Cell voltage is only 1.2 Volts which means that many cells are required to make up high voltage batteries

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As the oldest production Printed Circuit Board Company in North America, perhaps in the world, the 60-year plus story of Epec is connected to the development of the PCB and the electronics industry.

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  • Epec Founded in 1952
  • IPC Founded in 1957
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