NicD Battery and NiMh Battery Differences

by DoItYourself Staff

What are the differences between a NiMh and an NiCd battery? Whether you need batteries for a laptop, camcorder, cordless phone of a nifty gadget, read on to learn the main differences between these power sources.

What is a NiCd Battery?

NiCd is an acronym for Nichel-Cadmium. These batteries are rechargeable and use potassium hydroxide as an electrolyte fluid. When voltage or power is applied between the positive and negative terminals, the electrons flow through the electrolyte fluid to the negative terminal supplying electricity to your product.

NiCd batteries have one major drawback called ‘memory effect,’ which occurs when the battery states that it is fully charged but in reality isn’t. For example the battery charger reads that the NiCd battery is fully charged but it may only be 60 percent full. When the battery is then used, it runs down faster, resulting in a lower life usage for your product. The memory effect is caused by the formation of cadmium crystals formation build-up within the battery. The best way to get around the memory effect is to use the laptop, camcorder or gadget until the power runs out, and then recharge it.

NiCd Battery Pros and Cons

Have at least 500 recharge cycles before the memory effect kicks in
Inexpensive, reliable and durable
Function well in low temperatures
Memory effect will reduce the battery's lifespan.
Cadmium is a toxic metal, which makes these batteries environmentally unfriendly.

What is a NiMh Battery?

NiMh or Nickel Metal Hydride batteries are similar to a NiCd battery in that it used potassium hydroxide as its electrolyte. These batteries are rechargeable and do not suffer from the ‘memory effect’ problem which plagues NiCd batteries. NiMh batteries hold twice the amount of amperage at a given voltage than a NiCd battery. For example, if both batteries have a voltage of 1.25 volts, then NiCD battery holds 600 to 800 amps while a NiMh holds 1600 to 1600 amps.

NiMh Battery Pros and Cons

40 to 50 percent higher energy density that a NiCD at a given voltage
Memory effect is a non-issue.
Environmentally friendly as they do not contain cadmium
Can not carry high loads
Limited service life

Which Battery Type Should I Choose?

Whatever the chemical makeup of the battery, it must be reliable and have a long recharge cycle life. The parameters you must consider are the memory effect, load and amperage requirements for your product. No matter which battery you choose you have trade-offs:

NiMh batteries do not suffer from the memory effect, but they have a lower life cycle than a NiCd battery.
NiCd batteries carry less amperage than a NiMh but NiCd’s can handle a greater electric load than a NiMh battery.
NiCd batteries are more durable, but they are not environmentally friendly.