What is the Difference Between NiMH and NiCd?

The main differences between nickel-cadmium (NiCd) and nickel-metal hydride (NiMH) batteries lie in their capacity, memory effect, and environmental friendliness. Here are the key differences:

1. Capacity: NiMH batteries have a higher capacity than NiCd batteries, which means they can power devices for longer periods.
2. Memory Effect: NiMH batteries do not suffer from the memory effect, which can cause devices to "forget" their ability to achieve a full charge over time. This is a problem that NiCd batteries often face.
3. Environmental Friendliness: NiMH batteries are more environmentally friendly than NiCd batteries due to the absence of toxic chemicals like mercury and lead in their composition.
4. Temperature Performance: NiCd batteries perform better at extreme temperatures compared to NiMH batteries.
5. Self-Discharge Rate: NiMH batteries have approximately twice the self-discharge rate of NiCd batteries, meaning they can lose their charge more quickly when not in use.
6. Charging and Discharging: NiMH batteries cannot handle high rates of charges or discharges (typically over 1.5-2 amps) as well as NiCd batteries.

When choosing between NiCd and NiMH batteries, consider factors such as capacity, environmental impact, and the specific requirements of your device. NiMH batteries are generally preferred for their higher capacity and eco-friendliness, while NiCd batteries may be more suitable for applications that require performance at extreme temperatures.

Comparative Table: NiMH vs NiCd

Here is a table comparing the differences between Nickel-Cadmium (NiCd) and Nickel-Metal Hydride (NiMH) batteries:

In summary, NiMH batteries have a higher capacity and lower self-discharge rate than NiCd batteries, making them more suitable for consumer electronics. However, NiCd batteries have a better performance at extreme temperatures and can be ultra-fast charged with minimal stress. NiMH batteries are also more environmentally friendly due to the absence of toxic metals.