Uh Larry, how can I determine whether it is negative ground?
I've looked around on it and the battery. I tried to test the battery
contacts w/ my multimeter, but the probes were too fat, and I wasn't sure
I'd be more than guessing which was the ground contact anyway.
I called Toshiba support, and he couldn't answer that kind of question.

"Larry" wrote in message
...
"Garland Gray II" wrote in news:x6%wf.6522$CV.6302
@dukeread03:

Thanks Larry. Is this caveat a separate issue from my charging issue ?
Regarding the charging, I would certainly observe polarity. But it would
receive from a fixed GPS thru a serial port.



AS long as the GPS, a negative ground device is not hooked to a positive
ground computer, it'll be fine. This all is a throwback to Japanese
engineers. Cars in Japan used to all be POSITIVE ground, and so was their
electronics! They also drive on the wrong side of the road, except to our
UK friends...(c;

"Garland Gray II" wrote in message
news:Zchxf.6624$CV.5318@dukeread03...
Uh Larry, how can I determine whether it is negative ground?
I've looked around on it and the battery. I tried to test the battery
contacts w/ my multimeter, but the probes were too fat, and I wasn't sure
I'd be more than guessing which was the ground contact anyway.
I called Toshiba support, and he couldn't answer that kind of question.

Look at your AC adapter for the laptop. The two that I have tell the input
and output voltages and show the polarity of the connect to the computer.

Leanne

Garland Gray II wrote:

Uh Larry, how can I determine whether it is negative ground?

Look at the battery. One of the two major cables from the two posts
will go to a ground like the engine block or the frame. On current cars
is is the negative (-) post.

Jack

--
Jack Erbes in Ellsworth, Maine, USA - jackerbes at adelphia dot net
(also receiving email at jacker at midmaine.com)

"Garland Gray II" wrote in
news:Zchxf.6624$CV.5318@dukeread03:

Uh Larry, how can I determine whether it is negative ground?
I've looked around on it and the battery. I tried to test the battery
contacts w/ my multimeter, but the probes were too fat, and I wasn't
sure I'd be more than guessing which was the ground contact anyway.
I called Toshiba support, and he couldn't answer that kind of
question.


Obviously, you're going to use your own 12V power cord after you figure
out which contacts on the plug are + and which are minus, right?
So....take the battery out so we don't blow the ohmmeter in your
multimeter with its DC, then measure from the + power wire to the shell
(ground) on the serial DB9 connector. If they are connected together,
it's positive ground. Try the same for the - power wire to audio and
serial ground.

I'm concerned about someone's comment their starting of the big diesel
blew a directly-connected notebook like this. Maybe all this is not a
good idea, after all.

Perhaps the $29 75-watt DC-to-AC inverter from any Radio Shack, which is
so efficient there's no fan and it's all built right into the plastic
plug, would be a better idea to plug your laptop's AC supply into. The
smaller the inverter, like this tiny one, the less its wasted idle
current drain. I doubt you could measure this little guy's DC unloaded
current without a milliammeter. Its LED indicator is probably its
largest idle load. Your notebook hardly draws 75 watts to charge the
battery and power the computer. If it won't, graduate to the 150W
version.

Got it..
And yes, I had taken note of Dennis' comment about voltage spikes. It
wouldn't be difficult, if the computer is plugged in, to switch off the 12v
outlet circuit before starting the engine, but that is something else to
remember.

"Larry" wrote in message
...
"Garland Gray II" wrote in
news:Zchxf.6624$CV.5318@dukeread03:

Uh Larry, how can I determine whether it is negative ground?
I've looked around on it and the battery. I tried to test the battery
contacts w/ my multimeter, but the probes were too fat, and I wasn't
sure I'd be more than guessing which was the ground contact anyway.
I called Toshiba support, and he couldn't answer that kind of
question.


Obviously, you're going to use your own 12V power cord after you figure
out which contacts on the plug are + and which are minus, right?
So....take the battery out so we don't blow the ohmmeter in your
multimeter with its DC, then measure from the + power wire to the shell
(ground) on the serial DB9 connector. If they are connected together,
it's positive ground. Try the same for the - power wire to audio and
serial ground.

I'm concerned about someone's comment their starting of the big diesel
blew a directly-connected notebook like this. Maybe all this is not a
good idea, after all.

Perhaps the $29 75-watt DC-to-AC inverter from any Radio Shack, which is
so efficient there's no fan and it's all built right into the plastic
plug, would be a better idea to plug your laptop's AC supply into. The
smaller the inverter, like this tiny one, the less its wasted idle
current drain. I doubt you could measure this little guy's DC unloaded
current without a milliammeter. Its LED indicator is probably its
largest idle load. Your notebook hardly draws 75 watts to charge the
battery and power the computer. If it won't, graduate to the 150W
version.