How Do Rechargeable Batteries Work? Learn About Secondary Cells, What They're Used For, Advantages & Disadvatages

How Do Rechargeable Batteries Work? Learn About Secondary Cells, What They're Used For, Advantages & Disadvatages
Page content

How Do Rechargeable Batteries Work?

The batteries that we use today can be classified into two types, Primary cells and Secondary cells. Primary cells are disposable batteries, like alkaline batteries. Secondary cells are rechargeables, like NiCd or NiMH. Let us concentrate on the Secondary Cells.

Rechargeable batteries work by fully restoring its energy capacity when an electric current is applied to them. They are considered to be electrochemical cells which produce a finite amount of energy, which once depleated can be recharged by reversing the chemical reaction with the aid of a charging current supplied by the battery charger.

Here are some of the more common chemistries used in rechargeables today:

NiMH - Nickel Metal Hydride

Li-ion – Lithium Ion

Ni-Cd – Nickel Cadmium

Li-ion polymer – Lithium ion polymer

Lead-acid – Combination of lead and Sulfuric Acid

Each technology has its own advantages. These may include: high power delivery for shorter periods of time, longer battery life for low power applications, quicker recharge rates, longer life times or smaller size for the same amount of energy. The designer should pick the most appropriate technology for the application.

What are the Basic Applications of Rechargeable Batteries?

Everyone who owns a cell phone, an MP3 player, or a portable gaming device knows that it has a rechargeable battery that needs periodic charging to keep it functioning. Probably an even more common and older application for rechargeable batteries, that everyone uses but never thinks about, is in the car or truck you ride in every day. There is a lead-acid battery that is used every time you start your car and provides the energy needed to run the lights and radio when the engine is not running. The battery is recharged as you drive the vehicle, ensuring that it has enough energy to start your car the next time.

The new hybrid and electric cars typically use the latest battery technology, which provide the most energy for the lightest and smallest battery packs.

Advantages Over Typical Disposable Batteries

There are several benefits that we can get in using rechargeable batteries.

  • These portable power sources can be used and re-used a great number of times. Depending on the technology used, rechargeable batteries can last up to 200 recharging cycles and some may even reach thousands.
  • Rechargeable batteries are considered renewable (for a finite time span) which makes them environmentally friendly. Because of their re-usability, there are fewer batteries going into the landfills.


Unfortunately, these types of batteries aren’t perfect. Here’s some reasons why:

  • Rechargeable batteries can be easily damaged or degraded if they are not charged properly. Always make sure that you use the proper charger when charging a device that uses rechargeable batteries.
  • Rechargeable batteries cost much more than ordinary disposable batteries. But when compared to the number of primary cells you are replacing with the rechargeable battery and the added recycling costs involved for those cells, the rechargeable batteries are cheaper.
  • Due to the elements and electrochemicals used in these batteries, they may be harmful to the environment if not disposed properly. There are organizations available to help reduce the potential health and environment hazards of rechargeable batteries by recycling them. It should be noted that primary cells offer their own hazards when it comes to the environment and should be disposed of properly.