Nickel-metal-hydride batteries are similar to the proven sealed nickel-cadmium battery 

Technology except that a hydrogen-absorbing negative electrode is used instead of the cadmium-based electrode.

This eliminates cadmium, a toxic material, while this substitution increases the battery’s electric capacity (measured in ampere-hours) for a given weight and volume. 

NiMH batteries and cells are now widely use. They have a number of highlight characteristics that have enabled them to be used.

Nickel-metal-hydride batteries: Basic Info

Environmental impact:  

NiMH battery technology has overtaken that of its NiCd brother because of its lower environmental impact.

The use of cadmium is of particular concern, and therefore the use.

In the European Union, EU, legislation refers to the Battery Directive has requires the use of NiCd batteries to be terminates for portable use by consumers.
While the use of toxic cadmium is removes from the NiMH cells the mining and processing of the other metals use pose some environmental threats.

Fortunately, when the NiMH batteries reach the end of life, most of the nickel can be recovered with relative ease.

Specific energy density:  

NiMH cells and batteries have a higher level of specific energy, i.e. the amount of energy that can be contained within a certain volume of weight. It can be between 60 – 100 W h / kg against 40 – 60 for a NiCd.

Output voltage:  

One particularly fortunate parameter is that they provide a cell voltage of 1.2 volts which is very similar to that of a NiCd, making them an almost direct replacement.


Many NiCd battery chargers used the increase in terminal voltage to detect the end of charge.

Specifically, This increase in voltage for NiMH cells is very small, and NiMH cells are averse to overcharging.

Care needs to be take in when charging these cells and batteries.


There’s One disadvantage of the NiMH cell is that it has a high rate of self-discharge. They can lose up to 3% of its charge per week of storage.

NiMH battery technology is tries, tested and proven to be suitable for a variety of commercial and industrial applications.

Its safety and reliability credentials are unparalleled in the market.

With over 50 years of experience, GP NiMH batteries combine these credentials.

With world-class manufacturing, rigorous testing and a proven track record of producing high-quality rechargeable batteries.