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DC/DC Adapter -- question

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Anonymous
a b D Laptop
September 28, 2004 4:27:02 AM

Archived from groups: comp.laptops,comp.sys.laptops (More info?)

I have just purchased a Kensington 33051 DC/DC power adapter (good
discount from CompUSA). It has multiple points for various computers.
I have an Averatec 3220HS and a Compaq Presario R3120US. The Kensington
web page (and their service support 800 number) does not say that it
supports either of these two computers. However, before I take it back,
I thought I would ask if anyone out there knows whether or not it might
work anyhow (without damage to either the adapter or to the computer).

Averatec uses 19V, 3.16amp which works out to 60 watts -- well within
the limitation of 75w peak stated on the adapter. The web page says
that an Averatec 3150 works using tip c, 19v plug. And Avertec Tech
support tells me that the same should work on my 3220. So far so good.

The Compaq uses 18.5v, 6.5amp which works out to 120w. Kensington says
that they do not supply an adapter rated at 120w. I have two
questions:
a. what might happen if I use the adapter anyhow? Do I just not get
enough power to charge batteries in the laptop? Or do I endanger the
laptop in some way?

b. The Kensington adapter does not have an 18.5vold plug, only 18v and
19v ones. If I were to attempt to use that adapter on my Compaq,
should I use the 18v plug (under voltage) or the 19v plug (over voltage)
or is either one close enough that it would not matter?

TIA

Finally -- I cross posted this into comp.laptops and comp.sys.laptops.
What is difference in the two groups? I also see a comp.sys.laptop on
the list.

--
R. Dale Shipp
dale@_delete_this_min.net

More about : adapter question

Anonymous
a b D Laptop
September 29, 2004 5:50:35 AM

Archived from groups: comp.laptops,comp.sys.laptops (More info?)

There are 3 parameters that the tips most likely control:

-Physical plug type (connector size, shape and type)
-Voltage
-Polarity

There is a chance (it's very slim) that the plugs also control current
limiting. I have seen this on occasion, but it's very, very rare (some
of the Xtend power adapters did it, but I'm not aware of any others).

18 vs. 19 volts, in and of itself, isn't an issue. Both are well within
the tolerance of each other.

However, the current requirement of the Compaq is a huge issue.
Basically, if you try it, one of 4 things will happen:

-it will work
-it will seem to work, but the adapter will probably over heat and fail
-blow a fuse in the adapter (which might be effectively destroyed)
-adapter sense over-current and shuts down (non-destructively)

Understand, much of this depends on what you are doing. Your compaq
doesn't draw 6.5 amps ALL the time, and in fact it may virtually never
draw that much. Basically, you have 4 watts to work with. That might
be enough for all the time, all the time when you are not charging
batteries, all the time when you are not burning a CD, etc., etc. (and
some combinations thereof).

The greater risk here is to the adapter, not the computer, by the way.
Not that there is zero risk to the computer (especially if the adapter
fails).


R. Dale Shipp wrote:
> I have just purchased a Kensington 33051 DC/DC power adapter (good
> discount from CompUSA). It has multiple points for various computers.
> I have an Averatec 3220HS and a Compaq Presario R3120US. The Kensington
> web page (and their service support 800 number) does not say that it
> supports either of these two computers. However, before I take it back,
> I thought I would ask if anyone out there knows whether or not it might
> work anyhow (without damage to either the adapter or to the computer).
>
> Averatec uses 19V, 3.16amp which works out to 60 watts -- well within
> the limitation of 75w peak stated on the adapter. The web page says
> that an Averatec 3150 works using tip c, 19v plug. And Avertec Tech
> support tells me that the same should work on my 3220. So far so good.
>
> The Compaq uses 18.5v, 6.5amp which works out to 120w. Kensington says
> that they do not supply an adapter rated at 120w. I have two
> questions:
> a. what might happen if I use the adapter anyhow? Do I just not get
> enough power to charge batteries in the laptop? Or do I endanger the
> laptop in some way?
>
> b. The Kensington adapter does not have an 18.5vold plug, only 18v and
> 19v ones. If I were to attempt to use that adapter on my Compaq,
> should I use the 18v plug (under voltage) or the 19v plug (over voltage)
> or is either one close enough that it would not matter?
>
> TIA
>
> Finally -- I cross posted this into comp.laptops and comp.sys.laptops.
> What is difference in the two groups? I also see a comp.sys.laptop on
> the list.
>
September 29, 2004 5:46:47 PM

Archived from groups: comp.laptops,comp.sys.laptops (More info?)

the 18.5V is not precise, most laptops will accept a variation.
Since 18v and 19v are both same distance from 18.5v.
I would say it is better to use 19v.

"R. Dale Shipp" <dale@_delete_min.net> wrote in message
news:MPG.1bc2b223cd36c3a8989702@news.md.comcast.giganews.com...
>I have just purchased a Kensington 33051 DC/DC power adapter (good
> discount from CompUSA). It has multiple points for various computers.
> I have an Averatec 3220HS and a Compaq Presario R3120US. The Kensington
> web page (and their service support 800 number) does not say that it
> supports either of these two computers. However, before I take it back,
> I thought I would ask if anyone out there knows whether or not it might
> work anyhow (without damage to either the adapter or to the computer).
>
> Averatec uses 19V, 3.16amp which works out to 60 watts -- well within
> the limitation of 75w peak stated on the adapter. The web page says
> that an Averatec 3150 works using tip c, 19v plug. And Avertec Tech
> support tells me that the same should work on my 3220. So far so good.
>
> The Compaq uses 18.5v, 6.5amp which works out to 120w. Kensington says
> that they do not supply an adapter rated at 120w. I have two
> questions:
> a. what might happen if I use the adapter anyhow? Do I just not get
> enough power to charge batteries in the laptop? Or do I endanger the
> laptop in some way?
>
> b. The Kensington adapter does not have an 18.5vold plug, only 18v and
> 19v ones. If I were to attempt to use that adapter on my Compaq,
> should I use the 18v plug (under voltage) or the 19v plug (over voltage)
> or is either one close enough that it would not matter?
>
> TIA
>
> Finally -- I cross posted this into comp.laptops and comp.sys.laptops.
> What is difference in the two groups? I also see a comp.sys.laptop on
> the list.
>
> --
> R. Dale Shipp
> dale@_delete_this_min.net
Related resources
Anonymous
a b D Laptop
September 30, 2004 8:48:05 AM

Archived from groups: comp.laptops,comp.sys.laptops (More info?)

R. Dale Shipp <dale@_delete_min.net> wrote in message
news:<MPG.1bc2b223cd36c3a8989702@news.md.comcast.giganews.com>...

> I have just purchased a Kensington 33051 DC/DC power adapter (good
discount from CompUSA). It has multiple points for various computers. I
have an Averatec 3220HS and a Compaq Presario R3120US. The Kensington web
page (and their service support 800 number) does not say that it supports
either of these two computers. However, before I take it back, I thought I
would ask if anyone out there knows whether or not it might work anyhow
(without damage to either the adapter or to the computer).

<snip>

You need the Belkin MP0004
(http://catalog.belkin.com/IWCatProductPage.process?Merc...
168834)

or the Targus PAPWR300U
(http://www.targus.com/us/product_details.asp?sku=PAPWR3...)

Both are 120W (they are actually the same unit).

The Belkin is about $80 (check pricegrabber.com for "Belkin MP0004").

The DC power jack on airlines probably won't be able to supply enough
current to operate the notebook (it'll be able to charge it when it's off
though), but your car lighter may just make it, since the notebook is
probably drawing much less than the maximum current that the stock power
brick supplies.

Remember that the 120W rating on the AC adapter has margin, plus it's rated
for maximum load (DVD writing, all USB ports powering devices at the maximum
amount, maximum screen brightness, highest power processor available in that
notebook series), wireless on, wired network on, highest allowable current
PCMCIA card installed, maximum memory, etc. I'd wager that if you measured
the current (DC in) on the R312OUS that you'd be in the 60W range.

Remember that the R3120US uses the Mobile AMDT Athlon XP-M processor 3000
(1.6GHz), which is around 25W-35W max depending on which voltage it is, but
the same R3000 series notebook is available with the AMD Athlon(TM) 64 3700+
(2.40 GHz) which I read is about 80W peak.

The R3120US uses the 32MB version of the Nvidia graphics, but the same
series can have the 64MB version, which also adds 1394. Ditto for a larger
hard drive being available.

Again, the best thing to do is to find someone the measure the actual
current. But this means temporarily cutting the DC side of the power brick
to get a meter in-line.

Manufacturers typically measure the maximum possible power consumption on a
platform by running a power virus application that make the system draw more
power than it would ever use normally, while at the same time maximizing
power draw on all sub-systems and ports. And of course they have to size the
power brick for a series of notebooks, with the most power hungry options in
terms of processor, disk, screen, graphics, memory, etc.
Anonymous
a b D Laptop
September 30, 2004 10:32:02 AM

Archived from groups: comp.laptops,comp.sys.laptops (More info?)

> The DC power jack on airlines probably won't be able to supply enough
> current to operate the notebook (it'll be able to charge it when it's off
> though),

According to documentation with every airline adapter I've owned, FAA
regulations require that airline power adapters inhibit battery
charging as a safety issue.
Anonymous
a b D Laptop
September 30, 2004 5:53:04 PM

Archived from groups: comp.laptops,comp.sys.laptops (More info?)

That's physically impossible. The airline sockets simply provide +12 to
+15 volts DC. They have no knowledge of or ability to control what it's
being used for. Furthermore, on many notebooks, the "power brick" is
only connected to the laptop itself with a "2-wire" connector, and even
it also has neither knowledge of nor ability to control what the power
is being used for.

Auto cigarette lighters can supply 10 to 30 amps at the cigarette
lighter, which is about 150 to 450 watts -- way more than any notebook
uses. I suspect that airline "empower" sockets won't supply the upper
end of that range, but I've been unable to discover what the maximum
current (or power) available is.


Lewin A.R.W. Edwards wrote:

>>The DC power jack on airlines probably won't be able to supply enough
>>current to operate the notebook (it'll be able to charge it when it's off
>>though),
>
>
> According to documentation with every airline adapter I've owned, FAA
> regulations require that airline power adapters inhibit battery
> charging as a safety issue.
Anonymous
a b D Laptop
September 30, 2004 5:53:05 PM

Archived from groups: comp.laptops,comp.sys.laptops (More info?)

> That's physically impossible. The airline sockets simply provide +12 to
> +15 volts DC. They have no knowledge of or ability to control what it's
> being used for.

That's true, but irrelevant. You might as well say that auto
manufacturers build cars that can be used in hit-and-run killings.

> Furthermore, on many notebooks, the "power brick" is
> only connected to the laptop itself with a "2-wire" connector, and even
> it also has neither knowledge of nor ability to control what the power
> is being used for.

It's not physically impossible by any means. Take as a case in point
the Compaq Armada M300, which is the most recent machine for which I
owned both airline and auto adapters. The airline adapter outputs a
lower voltage than the auto adapter. IIRC the laptop is rated for 19V
but will boot and run off as little as 13. However it won't go on
charge if the input voltage is less than ~18V. APM/ACPI will report
"AC connected, not charging". The auto adapter contains a small
switchmode DC/DC converter that steps up the vehicle's lighter voltage
to 19V.

I should point out that there are other more complex ways such a thing
can be achieved over only two wires, even without resorting to
different o/p voltages - numerous schemes exist to modulate control
signals onto a DC supply line, and it wouldn't be hard to implement
such a system.

I note that the aftermarket version of these adapters don't have the
Compaq limitation.

If you want to look up some of the references, ref p.3-2 of the M300
reference guide, TPM_170706-002.pdf on HP/Compaq's web site. If you
want to charge a battery, you must use either the AC adapter, a
docking base, or the Auto Adapter/Charger. The Aircraft Power Adapter
mentioned on the same page is a separate part. See page 3-6 "...
Aircraft Power Adapter can be used to run the computer but cannot be
used to charge a battery pack." I couldn't find the manual for that
actual product (the adapter itself), which has explicit language
stating that it's an FAA regulation.

A random searching on HP's site showed the same disclaimer for
numerous more recent products.
Anonymous
a b D Laptop
October 1, 2004 6:31:51 PM

Archived from groups: comp.laptops,comp.sys.laptops (More info?)

"Barry Watzman" <WatzmanNOSPAM@neo.rr.com> wrote in message
news:415C1053.2000401@neo.rr.com...
> That's physically impossible. The airline sockets simply provide +12 to
> +15 volts DC. They have no knowledge of or ability to control what it's
> being used for. Furthermore, on many notebooks, the "power brick" is
> only connected to the laptop itself with a "2-wire" connector, and even
> it also has neither knowledge of nor ability to control what the power
> is being used for.
>
> Auto cigarette lighters can supply 10 to 30 amps at the cigarette
> lighter, which is about 150 to 450 watts -- way more than any notebook
> uses.

Most lighter outlets are fused at 10-15 amps, I've never seen a 30 amp
lighter socket. The Empower sockets on airplanes are limited to about 5
amps, usually at 15 volts, so you're at 75 watts, which is sufficient for
normal notebooks, but maybe not some of the loaded, high Mhz, desktop
processor equipped notebooks.

Actually, he should be fine on both because he's got one of the lower power
configurations of the notebook in question.

And of course the EmPower jacks charge the battery of any device plugged
into them, the FAA can't control that! On one flight, I had an EmPower to
cigarette lighter adapter, and a triple outlet adapter, and I was charging
my PDA, notebook, and cell phone, all at the same time!

Too bad the EmPower system hasn't really taken off, so to speak. I've only
been able to use it on a couple of international flights. On one American
flight they had cigarette lighter style outlets on my coach seat.

> > According to documentation with every airline adapter I've owned, FAA
> > regulations require that airline power adapters inhibit battery
> > charging as a safety issue.
Anonymous
a b D Laptop
October 1, 2004 6:34:16 PM

Archived from groups: comp.laptops,comp.sys.laptops (More info?)

"Lewin A.R.W. Edwards" <larwe@larwe.com> wrote in message
news:608b6569.0409300532.238b8f8b@posting.google.com...
> > The DC power jack on airlines probably won't be able to supply enough
> > current to operate the notebook (it'll be able to charge it when it's
off
> > though),
>
> According to documentation with every airline adapter I've owned, FAA
> regulations require that airline power adapters inhibit battery
> charging as a safety issue.

The FAA may say this, out of concern for fires resulting from Li-Ion
batteries (i.e. the famous Apple combustible Powerbook), but I've never seen
a DC connector on a device that know about this regulation..
Anonymous
a b D Laptop
October 1, 2004 6:34:17 PM

Archived from groups: comp.laptops,comp.sys.laptops (More info?)

> The FAA may say this, out of concern for fires resulting from Li-Ion

That's what I assumed it was too, either specifically exploding
batteries or more generally flammable gases being vented during charge
cycle.

> batteries (i.e. the famous Apple combustible Powerbook), but I've never seen
> a DC connector on a device that know about this regulation..

See my more detailed reply to Barry...
Anonymous
a b D Laptop
October 2, 2004 5:53:38 PM

Archived from groups: comp.laptops,comp.sys.laptops (More info?)

In article <9eM6d.2551$Yr.1477@newsread3.news.pas.earthlink.net>,
scharf.steven@linkearth.net says...
> R. Dale Shipp <dale@_delete_min.net> wrote in message
> news:<MPG.1bc2b223cd36c3a8989702@news.md.comcast.giganews.com>...
>
> > I have just purchased a Kensington 33051 DC/DC power adapter (good
......
>
> Remember that the 120W rating on the AC adapter has margin, plus it's rated
> for maximum load (DVD writing, all USB ports powering devices at the maximum
> amount, maximum screen brightness, highest power processor available in that
> notebook series), wireless on, wired network on, highest allowable current
> PCMCIA card installed, maximum memory, etc. I'd wager that if you measured
> the current (DC in) on the R312OUS that you'd be in the 60W range.
......

Thank you much for that very informative and technically loaded post.
It went a long way to explaining the various considerations.

In the end, I have decided to stay with the Kensington Adapter I bought
(72 w power) since it works with the smaller laptop (the Averatec) I am
most likely to use in the car. From what you and others have said, the
adapter will most likely do a reasonable job for the bigger laptop (the
Compaq) and in any case is unlikely to cause damage to either the
computer or the adapter.

--
R. Dale Shipp
dale@_delete_this_min.net
Anonymous
a b D Laptop
October 2, 2004 10:03:03 PM

Archived from groups: comp.laptops,comp.sys.laptops (More info?)

Re: "Take as a case in point the Compaq Armada M300, which is the most
recent machine for which I owned both airline and auto adapters."

In almost all cases, there are not separate auto/airline adapters at all
-- it's the same adapter. Further, it's almost always a "universal"
adapter, for example those made by Targus. They output the exact same
voltage whether used in a car or a plane, becuase the output voltage is
controlled by the "power tip". For what it's worth, most laptop vendors
don't even offer an "auto/air" (or auto OR air) adapter of their own;
Toshiba, for example, resells the Targus universal adapter. To go even
further, Radio Shack sells (and I have used) an "Empower to Cigarette
lighter". It's a cigarette lighter socket that plugs into an Empower
socket. The device subsequently plugged into it doesn't even know that
it's not in an automobile.

I'll give you that you've shown that it's not physically impossible to
build a laptop system that will run, but not charge, when used in an
aircraft. However, I'd guess that in fact, such systems account for
only a low single-digit percentage of actual systems.
Anonymous
a b D Laptop
October 3, 2004 2:24:12 AM

Archived from groups: comp.laptops,comp.sys.laptops (More info?)

"Lewin A.R.W. Edwards" <larwe@larwe.com> wrote in message
news:608b6569.0409301050.6a4e8522@posting.google.com...
> > That's physically impossible. The airline sockets simply provide +12 to
> > +15 volts DC. They have no knowledge of or ability to control what it's
> > being used for.
>
> That's true, but irrelevant. You might as well say that auto
> manufacturers build cars that can be used in hit-and-run killings.
>
> > Furthermore, on many notebooks, the "power brick" is
> > only connected to the laptop itself with a "2-wire" connector, and even
> > it also has neither knowledge of nor ability to control what the power
> > is being used for.
>
> It's not physically impossible by any means. Take as a case in point
> the Compaq Armada M300, which is the most recent machine for which I
> owned both airline and auto adapters.

All the aftermarket adapters I've seen and owned are "auto/air" adapters.
They put out the same voltage whether connected to an EmPower jack or a
ligher outlet (and in fact some airlines use cigarette ligher outlet jacks.

It's certainly possible to have two separate adapters, with an airline
adapter that puts out a lower voltage, though I've never seen one myself.
The one's I've seen all use a DC/DC adapter with a selection of tips to
select the voltage and polarity and the right mechanical size.
Anonymous
a b D Laptop
October 4, 2004 7:41:21 PM

Archived from groups: comp.laptops,comp.sys.laptops (More info?)

"Barry Watzman" <WatzmanNOSPAM@neo.rr.com> wrote in message
news:415EEDF0.6090403@neo.rr.com...
> Re: "Take as a case in point the Compaq Armada M300, which is the most
> recent machine for which I owned both airline and auto adapters."
>
> In almost all cases, there are not separate auto/airline adapters at all
> -- it's the same adapter. Further, it's almost always a "universal"
> adapter, for example those made by Targus.

I just got the iGo adapter which is an AC/Airline/Auto adapter all in one.
Eliminates the need to carry both an AC adapter and a DC adapter when
traveling. It has two power cords, one is an AC cord, one is a combination
lighter/EmPower cord. It came with eight tips, and other tips are available.
Cellular phone tips are available too, though a USB phone charger may be
more practical since you can charge both the notebook and the phone at the
same time.
!