What is a NiCad Battery?

• A NiCad battery is also known as a nickel-cadmium battery. They utilize a nickel oxy-hydroxide anode and a cadmium cathode flattened together and rolled into a spiral cylinder. Between the cathode and anode is an alkaline electrolyte fluid called potassium hydroxide. This acts as a catalyst between the cathode and anode, causing two separate chemical reactions which result in an electrical charge. These batteries are typically longer lasting than normal lead-acid batteries and can be recharged when needed. During the recharge process, the anode and cathode reactions are simply reversed until the battery has regained its maximum potential to produce electricity.
  
  

Anode Reaction

• In the anode one cadmium molecule fused with one hydroxide molecule is combined with two free electrons. The ensuing reaction results in a separate cadmium molecule and two Hydroxide ions, meaning they have developed a negative electrical charge by combining with the free electrons.
  
  

Cathode Reaction

• In the cathode portion of the battery, the hydroxide ions arrive from the cathode via the potassium hydroxide electrolyte. The negative ion is drawn to the charge present in the cathode. One nickel molecule combines with two regular hydroxide molecules as well as one hydroxide ion. The sum total of this reaction is one molecule of nickel oxy-hydroxide, water and free electrons, completing the circuit and delivering an electrical charge.
  
  

Overcharge Reaction

• The overcharge reaction occurs when the battery is being recharged although it already contains the maximum charge it's capable of holding. The oxy-hydroxide in the anode is converted by the excess electricity running through it into oxygen gas, water and free electrons. A typical NiCad battery has a vent within it designed to release the excess gas and water when the interior of the battery reaches a certain pressure limit. Unfortunately the potassium hydroxide electrolyte fluid is also lost during the venting, drastically reducing the battery's capacity to hold and generate a charge. After several repeats of this process, the battery will be dry and no longer function.