power inverter

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jinxy

Hey all, I am looking to pirchase a power inverter for my car to power
my laptop on a road trip. The laptop is a Toshiba and it looks like
19v on the adapter. Any suggestions on what size and how many watts I
should have to run the laptop without any power issues? Thanks,
Jinxy
 
Hey all, I am looking to pirchase a power inverter for my car to power
my laptop on a road trip. The laptop is a Toshiba and it looks like
19v on the adapter. Any suggestions on what size and how many watts I
should have to run the laptop without any power issues? Thanks,
Jinxy
Click to expand...

While you can purchase a 12 volt to 19 volt power adapter just for your
laptop you might want to consider one that converts from 12 to 115 volts
so you can use it on other things as well. The trick is to make sure
you get an actual Sign Wave output from the power converter. Here is a
link to an example of what I am describing which should get you on your way.

http://www.stealth316.com/2-samlex-inverter.htm
 
jinxy said:
Hey all, I am looking to pirchase a power inverter for my car to power
my laptop on a road trip. The laptop is a Toshiba and it looks like
19v on the adapter. Any suggestions on what size and how many watts I
should have to run the laptop without any power issues? Thanks,
Jinxy
Click to expand...

I can see one here, as an example.

http://www.amazon.com/Universal-Laptop-Power-Adapter-Automobile/dp/B000EXVRSM

You need to know the power in watts, that the existing AC adapter
can handle. Check the label of the laptop adapter for details.
Laptops come in several standard power levels ("watts"), and
your Automotive adapter should match the wattage rating.

The Amazon unit, looks to have a slide switch, which sets the
voltage. If your laptop currently uses 19V, you'd set the
switch to 19V.

The conversion type is "DC to DC", and would likely
take the form of a boost, or buck-boost converter. Buck
mode would be needed, if the input was 16V (high battery)
and the laptop was a 15V type. For more typical battery
voltages, the DC to DC converter would be running
in boost mode.

Power: Input: 11.8-16V DC-8A max, Output: 15-24VDC 70W Max

It's basically a switch mode power supply.

If I purchased one, I would

1) Measure the existing adapter and its barrel connector.
Is the center pin (+) or (-) ? What voltage does
the laptop adapter really put out ?

2) Next, measure your newly purchased automotive adapter.
Check that the polarity is the same, and that when the
adapter is switched to 19V, it actually produces 19V
on the output. If the polarity is wrong, the laptop
could be ruined.

There is evidence, that laptops have a relatively narrow
operating range on voltage. If a laptop needs 19V, you
can feed it perhaps from 18.5V to 19.5V. They don't
seem to have "wide range" input from the adapter. Why
that is, I don't know, as intrinsically, a lot of power
conversion circuits can have wide range input. I've heard
of at least one laptop owner in these groups, who
used a universal laptop adapter replacement and had the laptop
damaged after one month of usage of the (slightly wrong)
adapter. So don't depend on your laptop to accept insults,
on its power quality.

While the above rating "Input: 11.8-16V" implies the
battery in the car is benign, there are other specifications
the adapter must support. There can be up to 70V transients
on the automotive power bus, due to things like startup.
So the adapter actually has to support a certain level
of insults from the car itself. That's what distinguishes
"ordinary" electronics from "automotive" devices, is
the automotive one is designed to take the known
transients.

A good adapter, should also automatically cut itself off,
below a certain voltage, to prevent damage to the
automobile battery. If you're sitting in the car, with
the engine off, and using the laptop, eventually you
could discharge the car battery below an acceptable level.
Doing so, shortens the life of the car battery (after
you get a boost from someone, to get the engine running
again). It's not recommended to "deep-discharge" car
batteries frequently.

Paul
 
Hey all, I am looking to pirchase a power inverter for my car to power
my laptop on a road trip. The laptop is a Toshiba and it looks like
19v on the adapter. Any suggestions on what size and how many watts I
should have to run the laptop without any power issues? Thanks,
Jinxy
Click to expand...

Which Tosh? That helps us make better guesses.

If its a netbook like the NB 3xx models, lotsa choices

Check IGO

http://www.igo.com/power/laptops/icat/highpower/

I'm not finding the one I have but it was $30 at Office Depot a couple
of years ago. The **nice** part is that this one is both 100-240VAC
*and* 12VDC, just choose yer cord.

It appears the current one is:
http://www.igo.com/laptops/netbook-travel-charger/invt/ps001280004/

It powers my Tosh netbook just fine, but takes about 20% longer to
charge the battery than the Tosh "brick". That's not a big issue, at
least to me

The only warning I have is don't trust the "power tip adapter" to stay
on the cord when moving it around. If it falls off and you lose it, yer
hosed.
Tape it or glue it to the cord.

I've lost mine at least twice before I wised up to that issue.



--
"Shit this is it, all the pieces do fit.
We're like that crazy old man jumping
out of the alleyway with a baseball bat,
saying, "Remember me motherfucker?"
Jim “Dandy” Mangrum
 
Which Tosh? That helps us make better guesses.
If its a netbook like the NB 3xx models, lotsa choices

Check IGO

http://www.igo.com/power/laptops/icat/highpower/

I'm not finding the one I have but it was $30 at Office Depot a couple
of years ago. The **nice** part is that this one is both 100-240VAC
*and* 12VDC, just choose yer cord.

It appears the current one is:http://www.igo.com/laptops/netbook-travel-charger/invt/ps001280004/

It powers my Tosh netbook just fine, but takes about 20% longer to
charge the battery than the Tosh "brick". That's not a big issue, at
least to me

The only warning I have is don't trust the "power tip adapter" to stay
on the cord when moving it around. If it falls off and you lose it, yer
hosed.
Tape it or glue it to the cord.

I've lost mine at least twice before I wised up to that issue.

--
"Shit this is it, all the pieces do fit.
  We're like that crazy old man jumping
out of the alleyway with a baseball bat,
saying, "Remember me motherfucker?"
Jim Dandy Mangrum

Which Tosh? That helps us make better guesses.
Click to expand...

The Toshiba in question is a Satellite C650-025 19V- 3.42A.
 
Probably in the 250 watt range.  I've used the DC-AC versions for years
with my laptops.

Suspect that frys.com will have them listed as they keep a large stock
in their stores.
Click to expand...

I am going to Canadian Tire to pick-up a 75w unit for $14.95. Thanks
to everyone that replied.
Jinxy
 
jinxy said:
I am going to Canadian Tire to pick-up a 75w unit for $14.95. Thanks
to everyone that replied.
Jinxy
Click to expand...

Is it this one ?

http://www.canadiantire.ca/AST/brow...inator%2B75W%2BPower%2BInverter.jsp?locale=en

It is a "75 watt" unit, with a "60W continuous power" rating.

You probably want one a step larger than that, if you're going
to plug the laptop adapter into it. That will help compensate
for any difference between "watts" and "VA" hidden in the unit
rating. Perhaps a 150W unit would be a better choice.

If the laptop adapter had Active PFC (power factor correction),
then the laptop adapter would be purely resistive. If not,
switching adapters without power factor correction, have the
voltage and current waveform out of phase a bit. Getting
the next size larger 115V inverter, will give you some margin
to work with.

And, holy crap, the first customer review for that unit, says this:

"Not enough oomph for laptop Date: July 9, 2011

Overall, a disappointment.

We purchased one of these on sale at $14.99. At first, it
would power my computer, but after only a few months of use,
it will no longer run a laptop."

Ouch.

Paul
 
I am going to Canadian Tire to pick-up a 75w unit for $14.95. Thanks
to everyone that replied.
Jinxy
Click to expand...

Just be aware that many of these cheapie inverters are really funky on
"low battery level cutout", especially with a light load.

I went thru about 9 different makes and modules (and tried at least 2 of
each) last year.

What I was trying to accomplish:
Run a moderate 120VAC fan in my wurk truck (mainly), with some other
stuff like laptop/phone/tool chargers and a Dremel tool at times.

There was no A/C in the truck, and the dash blowers in the '01 Chev van
weren't worth crap when parked, *plus* the batt drain was far higher.

(I've used this inverter/120VAC fan stunt in the past when on contractor
and/or safety watch, hours of sitting in the truck)

Far too many of those $12-$35 inverters would shut down if the batt
dropped below ~11.7V, even for an instant.

I'd be sitting with a decent breeze in my face, key off and then key up
the mic on the 2-way to respond to a page, and the inverteter would shut
down and stay down. The only way to restart the inverter was unplug it,
start the rig and plug it back in.

There was one unit from AutoZone that worked ok, but I gave it away to
another cohort at work when I retired.





--
"Shit this is it, all the pieces do fit.
We're like that crazy old man jumping
out of the alleyway with a baseball bat,
saying, "Remember me motherfucker?"
Jim “Dandy” Mangrum
 
Also, the 200W one has a hint from a reviewer.

http://www.canadiantire.ca/AST/brow...nator%2B200W%2BPower%2BInverter.jsp?locale=en

"Since this inverter results in a “non-sinusoidal” AC voltage, in some
rare cases, it may have some varying negative effects on electronics
that specifically require sinusoidal AC voltage if used for long periods."

If the laptop adapter has Active PFC, then this would be something to
watch for. Square wave output inverters and Active PFC units
aren't a good combination. Sine wave output inverters (true sine)
would be a better choice.

If a switching adapter, like the laptop one, has no power factor
correction, then in fact, the basic switching regulator is perfectly
happy with square waves. When they place a PFC circuit in front
of the switcher, that's the thing that "looks for a sine wave",
and tries to compensate for the non-ideal nature of the switcher.
And this level of detail, may not be printed on the packaging
of the original laptop adapter. (PFC is there, to help the
power company, and not the consumer. In fact, it drops power
supply efficiency by a fraction of a percent.)

North American ATX supplies, are slowly all being replaced with
Active PFC units. It's getting hard to find an ATX supply without
that. I don't know if that trend, extends to laptop adapters
or not. (That's why I bought my Sparkle power supply the last
time I was looking, as it had no PFC.)

You're not going to solve this problem for $14.95.

In that sense, the automotive laptop adapter is a better choice, because
it does DC to DC conversion directly, so there are no 115V A.C. characteristics
to worry about at all. All you have to worry about, is it delivers
the right DC voltage (like the 19 volts or whatever), and the
barrel connector is the right size. (There are 15 or more
styles of barrel connector.)

*******

This one is "modified sine". That is a step approximation to a sine
wave. Still not perfect.

http://www.amazon.com/Go-Power-GP-3...BH6M/ref=sr_1_4?ie=UTF8&qid=1310418365&sr=8-4

This unit is "pure sine", but one reviewer notes it seems to have
the low battery setting, set too high. The unit cuts off the
laptop, when the vehicle comes to a halt at stop lights.

http://www.amazon.com/Wagan-EL2200-...J3VI/ref=sr_1_1?ie=UTF8&qid=1310418365&sr=8-1

So the reviews (where ever you shop), can be very helpful in
identifying a good one.

This is especially interesting. Go Power! GP-SW150-12 150-Watt
Pure Sine Wave Inverter, load characterization.

http://www.amazon.com/review/R1GY89AXJSP8A4/ref=cm_cr_pr_viewpnt#R1GY89AXJSP8A4

"Load in watts with its respective Go Power! inverter voltage
0w - 113.3v AC
5w - 112.8v AC
15w - 112.5v AC
24w - 112.0v AC
43w - 111.1v AC
73w < 104.0v AC (attached devices powered themselves off due to low voltage)

[Input = "12 volt, 35 amp hour battery pack, voltage level 13.21v DC"] "

Now, even though that unit has double the output load rating, the output
characteristic is dangerously close to unacceptable for a 65W laptop.
104V is getting too close to the lower limit.

Paul
 
Also, the 200W one has a hint from a reviewer.

http://www.canadiantire.ca/AST/browse/4/Auto/SolarPortablePower/Inver...

    "Since this inverter results in a non-sinusoidal AC voltage, in some
     rare cases, it may have some varying negative effects on electronics
     that specifically require sinusoidal AC voltage if used for long periods."

If the laptop adapter has Active PFC, then this would be something to
watch for. Square wave output inverters and Active PFC units
aren't a good combination. Sine wave output inverters (true sine)
would be a better choice.

If a switching adapter, like the laptop one, has no power factor
correction, then in fact, the basic switching regulator is perfectly
happy with square waves. When they place a PFC circuit in front
of the switcher, that's the thing that "looks for a sine wave",
and tries to compensate for the non-ideal nature of the switcher.
And this level of detail, may not be printed on the packaging
of the original laptop adapter. (PFC is there, to help the
power company, and not the consumer. In fact, it drops power
supply efficiency by a fraction of a percent.)

North American ATX supplies, are slowly all being replaced with
Active PFC units. It's getting hard to find an ATX supply without
that. I don't know if that trend, extends to laptop adapters
or not. (That's why I bought my Sparkle power supply the last
time I was looking, as it had no PFC.)

You're not going to solve this problem for $14.95.

In that sense, the automotive laptop adapter is a better choice, because
it does DC to DC conversion directly, so there are no 115V A.C. characteristics
to worry about at all. All you have to worry about, is it delivers
the right DC voltage (like the 19 volts or whatever), and the
barrel connector is the right size. (There are 15 or more
styles of barrel connector.)

*******

This one is "modified sine". That is a step approximation to a sine
wave. Still not perfect.

http://www.amazon.com/Go-Power-GP-300-300-Watt-Modified/dp/B00153BH6M...

This unit is "pure sine", but one reviewer notes it seems to have
the low battery setting, set too high. The unit cuts off the
laptop, when the vehicle comes to a halt at stop lights.

http://www.amazon.com/Wagan-EL2200-Elite-Watt-Inverter/dp/B003INJ3VI/...

So the reviews (where ever you shop), can be very helpful in
identifying a good one.

This is especially interesting. Go Power! GP-SW150-12 150-Watt
Pure Sine Wave Inverter, load characterization.

http://www.amazon.com/review/R1GY89AXJSP8A4/ref=cm_cr_pr_viewpnt#R1GY....

    "Load in watts with its respective Go Power! inverter voltage
     0w - 113.3v AC
     5w - 112.8v AC
     15w - 112.5v AC
     24w - 112.0v AC
     43w - 111.1v AC
     73w < 104.0v AC (attached devices powered themselves off due to low voltage)

     [Input = "12 volt, 35 amp hour battery pack, voltage level 13.21v DC"] "

Now, even though that unit has double the output load rating, the output
characteristic is dangerously close to unacceptable for a 65W laptop.
104V is getting too close to the lower limit.

    Paul
Click to expand...

I went and bought the 75w unit, I have used it all the way to Daytona
Beach without a hitch. I am going to buy another for my daughters
lappy, it has the same power scheme as the one listed. So far so good.
They may even be a bit cheaper in the deep south.
Jinxy
 
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