Похоже у меня это
на форуме вот http://ubuntuforums.org/showthread.php?t=842551 прочитала
Dell chargers have a third wire (the central one). This connects DIRECTLY to the data pin of a memory chip in the charger. The memory chip stores an identification code that identifies the charger as made by Dell.
The BIOS in your Dell computer checks for the presence of this code. If it doesn't see it, it disables the ability to recharge your battery. You can have a perfectly good charger delivering perfect DC current, but if the laptop doesn't see the secret `made by DELL' code on the data wire, it punishes you for not using a Dell charger by refusing to charge your laptop battery.
To make matters worse, the inside of a charger is not a very hospitable place for a memory chip. They tend not to live long in such hot places. And connecting the data pin of a memory chip directly to an external wire is just lousy design. All you need is a single static spark to hit the data wire and zap - you've fried the memory chip with the Dell secret code. If the memory chip dies, your laptop won't recognise that the charger is made by Dell any more and will refuse to charge your laptop.
Для тех, кто не говорит по ангийски: зарядки Dell имеют идентификационный код, который хранится на чипе внутри зарядки, этот чип часто сгорает и тогда комп отказывается заряжать батарею, потому как думает, что зарядка не Dell-кая.