And on, and on...

THE MATERIAL WORLD: Batteries are what the marketing world calls a distress purchase - something you don't want to buy but have to Photograph by Bob Powell

The portable battery has unleashed objects that used to be fettered to the living room wall by flex. Radios, once cased in wood and as big as TVs, shrank and can now be taken everywhere. The tinny rattlings of Walkmans beat in syncopated competition with the wheels of railway carriages and tube trains, while electrified watches can be heard beep-beeping every hour on the hour, usually in the cinema or during a funeral. Cameras are now powered by a tiny metal disc filled with lithium where once they weren't powered at all. Ambitious photographers, once to be seen performing strange arm movements while holding a lightmeter to the sky, now squint into a camera that measures the light and focuses all by itself.

Portable batteries have triggered the shrinkage of appliances, and have shrunk themselves. The cast-off portable radio that Gran gave me 25 years ago - wittily labelled "Playmate" by its manufacturer, Pye - demanded a squat 9-volt battery as big as a salt cellar and twice as weighty. Despite its bulk, it invariably had a brief life, especially if the Top Twenty was cranked up. The expense of replacing it invariably meant putting up with fading volume until the last dying crackle. That, of course, is the pain of owning something portable and electric - your batteries do not possess their powers for long, and cost more than pocket money to replace.

Batteries are what the marketing world calls a "distress" purchase - something you don't want to buy but have to. Even the purchase of a couple of 1.5-volt batteries for your Walkman can be enough to trigger a faint tremor of resentment. Years ago, the resentment would have been all the stronger because batteries were available only from electrical and hardware stores.

Today, they are one of the most widely distributed items in the country, to be found in more than 100,000 shops. The incentive to stock batteries is obvious when you discover that the nation buys some 420 million a year, a third of them at Christmas. The demand is created by the fact that the average British household contains some 11 battery-operated appliances, ranging from the TV remote control to alarm clocks, portable stereos, radios, smoke alarms, cameras and toys.

Around 25 years ago, Ever Ready dominated this market, but was soon to receive a near-paralysing shock from Duracell, an American company that made a longer-lasting battery. Indeed, compared to the butterfly life of the typical battery, the Duracell seemed too good to be true, lasting five to six times as long. The distinctive-looking black and copper cylinder had another advantage - it didn't leak. Many an appliance has been destroyed by a dying battery oozing the white powdery goo that gradually consumes your appliance's terminals.

The Duracell's secret lies in its chemistry. It uses many of the constituents of the traditional battery, but, crucially, the electrolyte is alkali rather than acid-based - it's the acid that eventually causes your traditional battery to decompose.

So, what's the catch? Inevitably, the price. Duracell batteries cost several times the price of an Ever Ready initially, and are around 70 per cent more now. But it didn't take long for the public to realise the advantages of spending more in the first place. The battery's simple advantage was most memorably demonstrated in a TV ad featuring platoons of pink drumming bunnies, some powered by Duracells, others not. Predictably, the Duracell rabbits beat their instruments long after their zinc-acid equipped rivals had fallen silent, but there was something acutely ludicrous about the scene that is unforgettable.

Ever Ready almost completely surrendered to the pink bunnies because it was too slow to react. Eventually, it fought back, by offering alkaline batteries itself. The upshot is that most of the batteries we buy today are the longer-life variety.

Like the car, batteries have given us a kind of freedom - the freedom to change TV channels without moving, the freedom to dull the tedium of travel with music. And longer-lasting batteries mean that we're reminded less often that freedom has its price