All you need to know about batteries.


There are various types of battery based on different chemistries. To get the best out of them and to avoid problems you need a basic understanding of their advantages and disadvantages, as well as a little about purchasing, maintaining and disposing of them.


  • Old batteries often leak, causing corrosions of the battery contacts, so preventing new batteries from working.
  • Lithium batteries can catch fire and burn violently if over-charged, shorted, punctured, or physically damaged in any way.
  • Button cells must be kept away from small children. If swallowed, this is a medical emergency as death can result in just a few hours, as a result of electrochemical action in the stomach.

How batteries work

(You can skip this section if you like, though a little more knowledge than you actually need is always helpful.)

Non-rechargeable (primary) batteries

Type Advantages Disadvantages Comments
Zinc carbon and zinc chloride
  • Cheap.
  • Available in standard shapes and sizes.
  • Short life and slow death.

Zinc chloride is a heavier duty version of zinc carbon. Alkaline batteries are preferred in almost all applications.

  • Good life at a reasonable cost.
  • Available in standard shapes and sizes, and also as button cells as cheap alternatives to silver.
This is the most economic general purpose type.
Silver oxide
  • High capacity
  • Expensive

Normally only available in small sizes as button cells for watches and calculators, on account of the cost.

  • Very high capacity
  • Short life once the tab has been remove to activate it by letting the air in

Used in hearing aids in the form of button cells.

  • Very long shelf and service lives.
  • Relatively expensive.

Various different lithium-based chemistries have somewhat different characteristics. Mainly used in smoke alarms and cameras.

Rechargeable (secondary) batteries

Type -

Nominal voltage

Advantages Disadvantages Comments
Lead Acid - 2V
  • Rugged and reasonably cheap.
  • Lead is toxic and cannot be disposed of in landfill.
At its best when mainly kept fully charged, hence widely used for (petrol/diesel) car batteries, uninterruptable power supplies, emergency lighting, security alarms, but also used in milk floats, golf buggies etc. Smaller sizes generally come as non-spillable sealed units.
Nickel Cadmium (NiCd) - 1.2V
  • Very rugged
  • Can deliver a high current and accept a very fast charge
  • Contains cadmium, which is toxic
  • Repeated partial discharge causes a "memory effect"
Mainly used nowadays in power tools and radio controlled model boats and cars.
Nickel Metal Hydride (NiMH) - 1.2V
  • Greater capacity than NiCd
  • No toxic cadmium
  • No memory effect
  • Available as direct replacements for common sizes of non-rechargeable batteries
  • Relatively high self-discharge rate
  • Low self-discharge variants have reduced capacity
  • May not work in all equipment designed to accept alkaline batteries on account of a lower voltage (1,2V as opposed to 1,5V for alkaline)

NiMH has replaced NiCd in all but specialist applications.

Lithium - 3.7V
  • Very high energy density
  • Very dangerous if abused. Protection circuitry is essential

As with primary lithium batteries, there are various chemistries and formulations with somewhat different characteristics.

External links

  • Battery University