My General Dynamics laptop which was discussed earlier is working like
a fine swiss watch. Now..Id like to rig up a power supply to run it
off my cigarette lighter jack in the vehicle. Should I get one of
those DC to DC converters found on Ebay? Or is there another way to
The laptop requires 19volts, 90 watts, to run, so obviously its not
going to work very well off a 13.75 power source very well.
Any suggestions would be helpful
I'm not sure the eBay DC/DC converters would handle 90W.
Lloyd's suggestion of an inverter sounds reasonable. You probably
already have one. They go on sale at HFT for $20ish often, if not.
The 200w models 61478 and 66967 are on sale for $23 now, and 400w
models are $26. They've gone up.
You never hear anyone say, 'Yeah, but it's a dry cold.'
-- Charles A. Budreau
The reason you want to keep the unit using it's own supply is reliability.
It was designed for 120v and it is designed to power the pc.
Supply the 120v and the pc will see the same signal. Maintain itself.
Just have a sine wave 120v so harmonics are not generated that might
do bad in a supply expecting a wall plug 120v 60Hz supply.
On 4/26/2016 10:00 AM, firstname.lastname@example.org wrote:
On Tue, 26 Apr 2016 22:26:50 -0500, Martin Eastburn
Unless I missed something, this thread is about laptops, which are
designed for ~20V DC input. You can get that from AC or DC adaptors
approved for the job.
I've had a good laugh reading this thread. The average 12 year old
needing a vehicle power supply for a laptop would probably google "car
laptop adaptor" and within an hour order one of a zillion available
adaptors for peanuts. But master electrician/electronics tech Wieber
plots yet another longest road to a corrupt solution. Soon he'll be
asking what size wire to use for his new inverter, and why his van
won't start after he cooked some road kill for a half hour in his
Get a life.
I know what I'm taking about - you don't.
I know the PC is a box. I know a supply powers the box.
The supply is trying to be replaced.
I say keep the supply as the impedance.... matches the box.
Simply have a supply that provides the input power of the supply.
e.g. 12V to 120 to 120 to 19v to box.
The 12VDC (boat/car/truck) delivers 120 V AC to the standard power
supply that came with the PC and that power supply powers the PC.
It makes a 12V to 19V supply with a 120vAC cable between...
On 4/27/2016 3:27 PM, email@example.com wrote:
On Fri, 29 Apr 2016 22:56:00 -0500, Martin Eastburn
Works fine, as long as you have an essentially unlimited supply of
electricity from the alternator on the running engine to cover the
losses in kicking the power up from 12VDC to 120VAC, then the
additional losses of going back down from 120VAC to 19VDC.
Unless you have other gear that also can use the 120VAC from the same
inverter, it's rather silly to convert it twice...
Now the kicker - If you are running off a battery or a
current-restricted power port, all of a sudden going straight from
12VDC to 19VDC at very low overall conversion loss starts looking a
whole lot better.
What pisses me off is that 19V changes with every generation of
computers, next year it will be 17V or 21V and a slightly different
connector, like the new Triaxial ones with a third communications pin
to allow battery charging control on Laptops - just so they can sell
you a new converter every time.
I have a stack of obsolete Auto-Air-Travel100-120-240 converters that
promised interchangeable connectors and variable voltage output so it
would be forward adaptable forever. And all of them were thwarted by
the Laptop industry making bigger changes than the vendors could
accommodate, like that third pin comm-port.
--<< Bruce >>--
On Sat, 30 Apr 2016 12:50:54 -0700, "Bruce L. Bergman (munged human
Since virtually all laptops today run on 10.7 volt batteries, they run
just fine on a "12 volt" power outlet but the batteries won't charge
fully (if at all)
The upconverter listed by someone earlier from e-bay works well for
the currents involved to make charging the battery possible.
All the cheapies are modified sine wave and I've heard that power tool
battery chargers don't like them much. I haven't tried my chargers on
either the old 400w or new 2000w HF inverters yet. The only test I
gave the big inverter was to see if it would power the chainsaw so I
could cut wood when the grid goes tits-up, and it did. I may need a
better inverter to power my furnace, too.
autmotive laptop charger, like this, but check connector sizes first
I made up an adapter cable that fed 14.x V straight from the car's
electrical system to the 19 V input of a Dell. It actually worked, but I
got nasty messages about a low battery.
I eventually bought one of the eBay 19 V converters, and it works great.
Being a big buyer of cheap Chinese gizmos, all I can say is: If it
needs 100w to run, buy at least a 300w converter, if not 400. They are
very competitive and not very honest with their figures. Kinda like
Searz horsepower, y'know? None of the vendors know -anything- about
power or tech specs, so if you ask them a question, make sure they ask
their engineer for the actual answer. Figure a week for a reply in
I can check tonight, but my guess is it has no name or other ID on the
thing. I bought it at least a year ago, and have used it on a Dell laptop.
I use that as a great big GPS when traveling, so the computer can stay on
for quite a few hours off the car's power.
I got the adapter off eBay, I'm pretty sure.
OK, it has a manufacturer's label that says Model: YD195-462 (but no
it also has a stick-on label that says www.sibusa.com and 43-2cc4
The web site www.sibusa.com just says "forbidden".
But, the YD195-462 model turns up some outfits that have them.
Hmm ... that it 4.74 Amps at your 19 V. I would aim for 5V as a
minimum, just to handle starting surges.
6.55 A from your 13.75 Volts from the car, assuming 100%
efficiency, which you won't get.
You *could* use one of the inverters to go to 120 VAC, and then
plug the power supply which belongs to the laptop into that. But that
is electrically inefficient. And -- make *sure* that the output
waveform is clean enough so the laptop's power supply won't barf.
Looking through Mouser's DC-DC power supplies, I find it
difficult to match what you need there, so you may be stuck with the
Now, this looks intersting on eBay (281797179064), though I
would like to be able to download a data-sheet/manual to read about it
in detail. However, it appears to accept any input voltage from 10V to
60V so it would cover your 13.75, plus the variations when the car is
running or stopped), and output from 12V to 60V. I see two pots on it,
one for adjusting the output voltage, and the other for adjusting a
current limit on the output.
It is $13.84 (plus possible import fees). :-)
My thoughts, and a quick look at eBay to see what you are
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