One thing you have to check when running a laptop directly from a
battery is which terminal is grounded in the laptop. If you connect
the serial interface you connect the grounds together via the cable.
or anything connecting them together could cause a short circuit even
if the serial interface is not used.
I power my HP laptop directly from a linear power supply rather than
use the noisy switching power supply. I measured the output voltage
of the laptop supply and found it to be 12.4 volts. The lowest the
linear supply would adjust to was 12.8v which is the voltage of a
charged lead acid battery, it has been running on this supply for more
than a year. The laptop had a negative ground even though the
polarity of the dc connector had the outside + and the center - the
reverse of the K2, so there was no problem connecting them together.
My laptop and the K2 could run from the same battery. In my case the
dc connector plugs are otherwise the same so you have to be sure they
don't get plugged in wrong. Don't assume the voltage of the battery
is the voltage of the power supply my laptop battery says 14.4v 2.5ah.
'73 James AI4CQ
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