Frodo is correct, but there is more. Car manufacturers will do anything to save just a few cents. (It’s a hazard of being in high volume production.) So, they do crazy things like using the car frame to carry the return current back to the battery. It creates absolutely crazy voltages and currents. Just turning your headlights off can create a pretty hefty voltage spike, as the electrical system madly tries to compensate for the reduced current flow. There’s a good reason why a car radio costs as much as it does. The guys who build it have to do a lot of work to protect the radio from the car’s “12 volts”.
And BTW, the fuse won’t protect you very much. Most of these regulators are series regulators, with a power transistor in series with the power outlet. 99% of the time, when a power transistor fails, it short circuits. Voila - 12 volts to your precious device. Most of the time, your device won’t pull enough current to blow the fuse until well after the damage is done. One of the standard EE jokes is that those expensive transistors will do a good job of protecting the fuses. The purpose of the fuse is to prevent a fire, not to protect your equipment.
When it happened to me, I had a Walkman-type tape player plugged in. When the music started playing really fast, I knew what had happened.
I’ve stopped using all the third-party chargers, including the iGo and others. It just isn’t worth it to me. I’m confident the Sony power brick is well built. And should it fail, Sony can’t dodge the warrenty. I admit I’m extreme. Most people will never experience a problem with their chargers. But I’m certainly not going to experience the problem. I like my lappy too much to feed it junk. :D
