Types of batteries and their differences

Alkaline Batteries:

• These are also sometimes called Primary Cells.
  
• Inside are two electrodes.
  
• One is made of Zinc, and the other is made of Manganese Oxide. These make up the positive and negative terminals respectively.
  
• The electrodes are surrounded by an alkaline electrolyte, hence their name.
  
• Unfortunately the chemical reaction in this does not go on for ever.Eventually, the electrolyte will be weakened and there will be no more voltage at the electrodes. This is when we decide to throw the battery away.
  
• Typically, a single 1.5V cell can provide 2,400mA/h. That is, it will provide 2.4 Amps continuously for 1 hour.
  
• In digital camera, as each time you take a picture there is a high surge of current which really drains the battery.
  

Nickel Cadmium Battery

• These are more commonly known as Ni-Cads, from their chemical formula of NiCd.
  
• In a similar way to the alkaline battery, two electrodes, one of nickel hydroxide and one of cadmium, are surrounded by a potassium hydroxide electrolyte.
  
• The thing that makes these batteries different to the alkaline batteries is that they can be recharged.
  
• This is achieved by passing a current through the electrodes and the electrolyte to reverse the chemical reaction, and hence make it new again.
  
• There is one drawback from NiCd batteries, though, and that is the ‘memory effect’. If you recharge the battery when it is not fully discharged, say when it is only 50% discharged, then next time you use it you will only be able to use it until it reaches this 50% discharge state.
  
• So, to re-charge NiCd batteries, make sure they are fully discharged first.
  
• They are able to provide a high burst of current, without too much effect on their overall status!!
  

NiMH Battery

• This is another type of rechargeable battery.
  
• The electrodes this time are Nickel and Mercury Hydride.
  
• These have an advantage over the NiCd batteries in as much that they do not have a memory effect, so you can re-charge them whenever you want without the need to fully discharge them.
  
• There is one very minor disadvantage compared to NiCd batteries though, and that is if you put them on a shelf for safe keeping they will discharge on their own quicker than their NiCd counterparts.
  
• Typically they are rated at 1300mA/h.