Rodney Myrvaagnes wrote:

The laptops I have used on boats--NEC, HP, IBM, and Toshiba-- all had
cigar lighter cords with no transformer. I suspect all that was inside
the bulge was overvoltage protection.


Are you sure about that? I have run Toshibas, Compaqs, and Thinkpads
from with both OEM and after market "auto" adapters. All of those had
to increase the voltage above the nominal 12 volts.

The good ones produced a steady and stable higher output voltage while
on the cheaper ones the output went up and down with the input but
stayed above it.

Some newer laptops have pretty robust DC-DC inverters and may run off of
anything that is close to right. But I'm too thrifty to test that
theory though because I have had some laptops that quickly fried DC-DC
inverters on ripply DC or under/over voltages.

Jack

--
Jack Erbes in Ellsworth, Maine, USA - jacker at midmaine dot com