Inverter For Running Laptop

[Dave]

I am thinking of getting one of the cheap inverters now available from
Jaycar/DSE etc to run my Acer Laptop. The Laptop PSU puts out 19V at
3.16 amp, which I make = 60W.

What puzzles me is that the input is rated as 100 - 240 Volts at 1.5
amp. Can I safely assume that this would be the current at 100V and
that at 240 Volts it would be substantially less ? From the size &
weight of it, it is obviously a switch mode unit and doesn't run
terribly warm.

I am hoping to run it off a 100W modified sine wave inverter - I
believe that Switchers are quite tolerant of modified sine wave ? Can
anyone confirm this or does anyone know of any problems with doing
this ?

I realise that it would be more electrically efficient to build a unit
to directly convert the 12V supply to 19V, but given the small amount
of time I intend to use the unit, I can't justify the time & I suspect
it may be as expensive as a cheap 240V inverter.

TIA

Dave

 

[John Burns]

Try this link:
Kerio Universal DC-DC Notebook Power Supply
http://www.dse.co.nz/cgi-bin/dse.storefront/en/product/M9695

I am using one on an acer laptop and found that the tip it advises to use
doesn't quite fit, I fixed this by buying a broken acer power supply and
hardwiring the acer end onto the dse adaptor.

-John

 

[Phil Allison]

I am thinking of getting one of the cheap inverters now available from
Jaycar/DSE etc to run my Acer Laptop. The Laptop PSU puts out 19V at
3.16 amp, which I make = 60W.

What puzzles me is that the input is rated as 100 - 240 Volts at 1.5
amp. Can I safely assume that this would be the current at 100V and
that at 240 Volts it would be substantially less ?

** Yep - the current draw will be ( more or less) inversely proportional
to the AC supply voltage.

I am hoping to run it off a 100W modified sine wave inverter

** Jaycar call their units "modified square wave" - which is a much
more correct description.

I believe that Switchers are quite tolerant of modified sine wave ? Can
anyone confirm this or does anyone know of any problems with doing
this ?

** Jaycar and DSE specify laptops as one of the typical uses for their
small inverters - you could ask store staff if any issues have cropped
up with them.






................ Phil

 

[Dave]

Thanks for the replies.

The Kerio unit certainly looks good apart from price ! I should be
able to get a 240V inverter for about $50 less.

As Phil says, they are advertised as being suitable for laptops so I
am probably just being a bit paranoid about potential damage.


Dave

 

[John Tserkezis]

I am thinking of getting one of the cheap inverters now available from
Jaycar/DSE etc to run my Acer Laptop. The Laptop PSU puts out 19V at
3.16 amp, which I make = 60W.

What puzzles me is that the input is rated as 100 - 240 Volts at 1.5
amp. Can I safely assume that this would be the current at 100V and
that at 240 Volts it would be substantially less ? From the size &
weight of it, it is obviously a switch mode unit and doesn't run
terribly warm.

That current is worst case. Not very indicative of the actual current flow,
which depends on how much the laptop takes, and the efficiency of the inverter.

I am hoping to run it off a 100W modified sine wave inverter - I
believe that Switchers are quite tolerant of modified sine wave ?

Should be. The crest factor is the important thing you should be aware of.
That is, because it's not pure sine, the peak is generally higher than the RMS
value compared to a sine wave. Generally you shouldn't have a problem, but
should be aware of this issue especially with square wave driven inverters.
In this case, the peak voltage may exceed the power supply's maximum input.

Can anyone confirm this or does anyone know of any problems with doing this ?

With regard to the Jaycar units, would be more of a problem of the inverters
not being tolerant of the laptop power supply. I've found some (well, all of
the Jaycar) modified sine units have overzealous current protection, in that
the initial current surge (no matter how quick or reasonable it is) triggers
the inverter into short circuit protection. It just sits there and beeps when
you plug in your supply.

The jaycar pure sine inverters work fine.

As far as I'm aware, the DSE modified sine units should be OK.

I would suggest you take your powersupply and perhaps the laptop into a store
and try it out. They should be happy to plug in a battery for a few moments to
verify operation. It only takes a few minutes to check, and saves you from
find out it doesn't work after you get home.

I realise that it would be more electrically efficient to build a unit
to directly convert the 12V supply to 19V, but given the small amount
of time I intend to use the unit, I can't justify the time & I suspect
it may be as expensive as a cheap 240V inverter.

There are 12-19v DC/DC converters available from jaycar pre-built, certainly
not worth making one yourself (your time would add up to a bought unit anyway).
I would recommened this first, (less stuff to carry, and less cabling) then
the inverter because it gives you more flexibility regarding other mains
equipment you can use as well.

 

[Spanky]

I am thinking of getting one of the cheap inverters now available from
Jaycar/DSE etc to run my Acer Laptop. The Laptop PSU puts out 19V at
3.16 amp, which I make = 60W.

I have used two Toshiba Laptops and a Compaq, also with 19V PSU's around the
3amp mark with the 100w from Jaycar without any problems. One of them has
been in my car for well over 12months with daily use.

What puzzles me is that the input is rated as 100 - 240 Volts at 1.5
amp. Can I safely assume that this would be the current at 100V and
that at 240 Volts it would be substantially less ? From the size &
weight of it, it is obviously a switch mode unit and doesn't run
terribly warm.

I put a meter on the 19V side of the Toshiba in my car and from memory it
was drawing around 1.5amps with the screen off and a little over 2.5amps
with the screen on.

I am hoping to run it off a 100W modified sine wave inverter - I
believe that Switchers are quite tolerant of modified sine wave ? Can
anyone confirm this or does anyone know of any problems with doing
this ?

I realise that it would be more electrically efficient to build a unit
to directly convert the 12V supply to 19V, but given the small amount
of time I intend to use the unit, I can't justify the time & I suspect
it may be as expensive as a cheap 240V inverter.

If it's going to be used in a car who really cares about the efficiency, I
wouldn't think the extra fuel it uses would even be measurable.

TIA

Dave

I've us

 

[Patrick Dunford]

** Jaycar call their units "modified square wave" - which is a much
more correct description.

Very true.

 

[Alex]

With regard to the Jaycar units, would be more of a problem of the inverters
not being tolerant of the laptop power supply. I've found some (well, all of
the Jaycar) modified sine units have overzealous current protection, in that
the initial current surge (no matter how quick or reasonable it is) triggers
the inverter into short circuit protection. It just sits there and beeps when
you plug in your supply.

Yep, this seems to happen to me too, at least for some laptops I've
tried.

Your best bet (if you choose an inverter over a DC-DC converter), as
another poster has mentioned, is to try it out before you buy it.

There are 12-19v DC/DC converters available from jaycar pre-built, certainly
not worth making one yourself (your time would add up to a bought unit anyway).
I would recommened this first, (less stuff to carry, and less cabling) then
the inverter because it gives you more flexibility regarding other mains
equipment you can use as well.

OTOH, if you have an inverter, you can run other mains equipment off
it as well.

Hope this helps.

Alex.
Ernie and bert don't live in my email address.