Sunday, August 13, 2006

Laptop batteries

Over the years I got quite used to the concept that computers are outdated after two years or so. But if you don't mind using an outdated computer, for example because you aren't playing games with 3D graphics, you can use a computer for many years. There are no "consumable" parts in a computer, unless something breaks down, a computer can run forever. So it came to some surprise to me that this is *not* the case for a laptop computer.

My Dell Inspiron 6000 laptop battery broke down, refusing to charge any more. The fancy LED display it has to check the charge has lights 1-3-5 blinking, which is the batteries way of saying "error". And some research on the internet resulted in the stupefying information that this was not unexpected. The battery is of the Lithium ion type, and you can't charge and decharge those indefinitely. If you did, at some point some resistance would build up internally, and the battery literally explodes. So all Li ion batteries have fancy electronics which shut the battery down after about 300 recharge / decharge cycles.

Even more surprising is that some amount of charging and decharging happens even if you have the laptop connected to the AC power supply all the time. So even if you never use your notebook in a mobile way, and just have it sitting on your desk connected to the mains power, at some point, a bit over a year usually, the battery will break down anyway. And then you will have to buy a new battery, which at $200 apiece is a nice little side business for the laptop manufacturers. A notebook battery is a consumeable. Only thing you *can* do, and that is what I am doing now, is to remove the battery while running the laptop from the AC power supply.

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