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A Battery of Problems

Though seemingly key to the idea of the portable computer – after all you can’t work ‘on the move’ without one – the humble battery has always been the poor relation when it comes to technological development.

In the absence of any other available technologies, many early laptops were powered simply by alkaline batteries. Others, such as the Zenith Data Systems SuperSport, and the Compaq LTE 286 laptop had NiCD (nickel cadmium) battery packs, while a few, such as the Macintosh portable, were even powered by sealed lead acid batteries.
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The Macintosh portable was powered by a sealed lead acid battery, a bit like the one you'll find under the bonnet of your car.
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This was a terrible state of affairs. It was 1989 and the basic battery technology behind the most advanced computers on the planet was effectively 90 years old. It was time to move on.

Finally, things began to change, but development progressed at snail's pace. Nickel metal hydride (NiMH) batteries arrived first but, despite offering superior capacity, still weren't perfect. They had a shorter lifetime than NiCD batteries, would self-discharge far more quickly and still suffered from the memory effect that afflicted NiCD.

Then there was a long gap during which machines had to rely on NiCD and NiMH batteries to supply their power until rechargeable lithium ion batteries began to appear towards the end of the Nineties. Lithium ion batteries did away with the memory effect associated with Nickel-based batteries and had a much slower rate of self-discharge.
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Lithium Ion batteries have allowed notebooks to become thin and light, while still working for hours on the move.
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But even lithium ion batteries have their disadvantages. They have a limited lifespan and suffer a gradual reduction in capacity over time, regardless of the number of times it may have been charged or discharged. And as has been recently publicised by Sony's massive battery recall of 2006, they have been known to overheat and explode occasionally too.

Despite this, the more recent appearance of lithium polymer technology and the promise of fuel cell technology, Lithium ion remains the practical battery of choice for laptops today.

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