The nickel-cadmium batteries have a similar structure to the Lead-acid, but instead of Lead, Nickel hydroxide is used for the positive plates and Cadmium oxide for the negative. The electrolyte is Potassium Hidroxide.

The nominal voltage o fan element of a Ni-Cd battery is 1,2 V, instead of the 2 V of the elements of the lead-acid battery. The Ni-Cd batteries resist freezing and thawing processes without any type of effect in their performance. High temperatures have a minor incidence on them than on the lead-acid ones.

The self-discharge values oscillate between 3 and 6% per month. Overloads affect them less. They may unload totally without suffering any damage. They do no have any sulphation danger. Their capacity to accept a load cycle is independent from temperature.

The cost of a Ni-Cd is much higher than a Lead-acid one; however, they need lower maintenance and a have longer life. This makes them suitable for isolated places or of dangerous access. The Ni-Cd batteries cannot be tested with the same reliability than the Lead-acid ones. Therefore, if it is necessary to control the state of the load, the Ni-Cd are not the best option. The Ni-Cd presents the so called "memory effect": the battery “remembers” the depth of the unload and reduces its effective capacity. This is due to the fact that the chemical compound that is made on a loaded plate tends to crystallize, so if it is left enough time it becomes useless and loses its capacity. This process is not irreversible, but it is difficult to be reversed.