Recently an LLNL employee left a
laptop computer on overnight in a soft carrying case, plugged into a
wall outlet. The computer, an Apple Titanium PowerBook G4, was in the
"sleep" (i.e., low-power) mode, with the carrying case closed. The next
morning, the employee discovered that the computer had overheated to the
point that the keys melted.
The damaged laptop.
This event is still under
investigation by Apple engineers and appears to be an isolated case.
However, many portable computers are used by LLNL employees at work and
home, and this incident serves as a reminder that portable computers
need to be operated with care.
What Was Learned
The cause of this incidence may
have been failure of the temperature sensor to automatically power down
the computer when it overheated.
Laptop computers should never be
left operating overnight in a soft carrying case or on any other soft
surface (even in the sleep mode).
The bottom of the Apple computer
case functions as a cooling surface to transfer heat from inside the
computer to the cooler outside air. The case bottom is slightly raised
to allow the airflow needed to cool the computer while in use.
The instruction manual for the
Apple computer clearly warns never to operate the computer on a soft
surface, which can block the airflow vents underneath the computer,
causing it to overheat.
A padded carrying case is
sufficiently insulated to cause a computer to overheat, even in a
Note: This Lesson Learned is not
limited to Apple computers.
User’s guides for other
manufacturers' portable computers caution not to block, push objects
into, or allow dust to accumulate in the air vents, as this may cause a
Other manufacturers also warn
against operating portable computers with the base resting on exposed
skin for extended periods of time, because the base surface can become
hot enough during normal operations to cause discomfort, or even burns,
to exposed skin.
Laptop computers should always be
operated on hard surfaces with unobstructed ventilation to avoid
If the computer must be operated
on a soft surface, an optional heat sink base can be used to assure
Do not use the heat sink in a
closed carrying case or similar environment that might obstruct
Review your laptop computer's
I'll certainly review the way I use mine!