When we stop to think about it, our civilisation would almost
grind to a halt without batteries. Without them, there would be no iPods, no
mobile phones, no handheld remote controls, no torches, no hearing aids, no
battery-powered radios, no cordless mice or keyboards and no cordless
telephones, to name just some of the equipment we now take for granted. Even
worse, we would have to hand-crank our cars to start them if we didn’t have
batteries to do the job for us!
Batteries were used to power many early valve radio receivers,
particularly in areas where mains power was unavailable. These batteries
consisted of both primary (non-rechargeable) and secondary (rechargeable) types.
A primary battery is one that uses up its chemicals in an irreversible reaction
and is disposed of after use (ie, after it has gone "flat"). By contrast,
secondary batteries can be recharged because the chemical reactions that take
place inside them are reversible.
