Laptop - "Airplane Mode"

Thread Starter


Joined Dec 12, 2008
This is connecting an air planes DC port to a laptop...

I am trying to understand the mechanisim where some laptops will sense a lower DC voltage input and only run the laptop and not try to charge the battery (until the unit is turned off).

Hewlett Packard says:

"The notebook detects the voltage of the in-seat power supply (15 V, 75 W) and disables battery charging automatically. The notebook must detect a voltage greater than 17 V to permit charging. With this protective measure in place, the battery can stay inside the notebook."

Is this part of the ACPI spec or the laptop's charger or software? We'd like to know if we can modify any "modern" laptop to have this "feature".

Thanks... RonR