Why Does an HP Adapter Get Hot?

AC adapters generate waste heat and can sometimes become very hot.

HP laptops, like all laptops, use external alternating current (AC) adapters which convert high-voltage alternating current electricity into lower-voltage, more stable direct current. Adapters of this type can become hot to the touch.

Adapter Functions

The AC adapter contains two circuits that ensure a steady, usable power supply for the computer or other device. A transformer lowers the voltage, while a regulator supplies electricity at a steady voltage, free of electrical "noise." These circuits use a small amount of electricity and generate a small amount of heat. AC adapters are usually slightly warm to the touch. They may be warmer when the device is using a lot of electricity, for example if it is running and charging its battery. There's no reason to worry about a hot adapter unless it's too hot to touch comfortably.

Internal Reasons

Adapters can sometimes overheat because the circuits in them, such as the regulator, are malfunctioning. If the part has gone bad, it may generate excess heat and have to be replaced. The appliance itself can sometimes draw too much power from the adapter, increasing the current flowing through it, causing it to become hot.

External Reasons

AC adapters rely on air passing over them to dissipate heat and cool them. If the adapter is covered, for example by a blanket or rug, the excess heat is trapped and the adapter will overheat. Always keep the adapter free from obstructions. If it has proper ventilation, it will remain at a moderate temperature.

References

• RepairFAQ: AC Adapter Basics