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12v laptop adapters?

 
 
Ron Hardin
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      02-07-2011, 09:28 AM
Any good suggestion for a 12v adapter for Dell laptops?

In particular, how do you know what works on what models.

Second, how efficient are they?

Low wattage is a plus - the concern is to run the laptop as long
as possible on the 12v battery, and not to recharge the laptop
battery. Maybe taking the internal battery out takes care of
that?

I assume that 12v to whatever DC-to-DC is more efficient than
going to a 115v inverter and the regular AC adapter, but maybe
not. Maybe the DC-to-DC already goes to an internal inverter
that's less efficient, who knows.
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who where
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      02-07-2011, 11:01 PM
On Mon, 07 Feb 2011 04:28:36 -0500, Ron Hardin
<(E-Mail Removed)> wrote:

>Any good suggestion for a 12v adapter for Dell laptops?
>
>In particular, how do you know what works on what models.
>
>Second, how efficient are they?
>
>Low wattage is a plus - the concern is to run the laptop as long
>as possible on the 12v battery, and not to recharge the laptop
>battery. Maybe taking the internal battery out takes care of
>that?
>
>I assume that 12v to whatever DC-to-DC is more efficient than
>going to a 115v inverter and the regular AC adapter, but maybe
>not. Maybe the DC-to-DC already goes to an internal inverter
>that's less efficient, who knows.


The first issue you need to address is whether the DC-DC approach will
work with your target Dell machine. The second is whether you can
source the DC connector to mate with the machine.

Apart from that:

.. the efficiency of DC-DC *could be* as high as 90-95%.

.. inverting to AC line voltage will be *approaching* that efficiency,
but depends on the inverter's output waveform. Square wave is
highest. Modified_sine_wave (which is really a modified square wave)
will be lower, and true sine wave output will have lowest efficiency.

.. some AC power supplies do NOT like operating on other than a
reasonable facsimile of a sine wave.

If the opportunity exists, try it.
 
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Timothy Daniels
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      02-08-2011, 02:45 AM
"Ron Hardin" wrote:
> Any good suggestion for a 12v adapter for Dell laptops?
>
> In particular, how do you know what works on what models.
> [........]


Try PowerBrixx.com. I did a search a year ago, and this
outfit had the best prices on the same stuff that Dell sells -
not the "just-as-good-as" and "equivalent-to" crap other sites
sell, but the same manufacturer part nos. Plus, their prices are
reasonable, and they ship immediately. They also have a guide
to which adapters to use with Dell laptops.
http://www.powerbrixx.com/c-27-dell.aspx

*TimDaniels*


 
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Ron Hardin
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      02-08-2011, 06:47 PM
Ron Hardin wrote:
>
> Any good suggestion for a 12v adapter for Dell laptops?
>
> In particular, how do you know what works on what models.
>
> Second, how efficient are they?
>
> Low wattage is a plus - the concern is to run the laptop as long
> as possible on the 12v battery, and not to recharge the laptop
> battery. Maybe taking the internal battery out takes care of
> that?
>
> I assume that 12v to whatever DC-to-DC is more efficient than
> going to a 115v inverter and the regular AC adapter, but maybe
> not. Maybe the DC-to-DC already goes to an internal inverter
> that's less efficient, who knows.


60w solar array indoors (so it's getting much less than 1/3 power) on a
dim sun day at noon can power an Inspiron mini 910, with a 60w cigarette
lighter inverter.

At least the 12v charge light on the 12v battery charge controller flicks
on and off, which means the solar array is more than keeping up with the
load on the battery.

Which means that when the power goes out and the gasoline runs out, at
least I can program, at least part of the day.

The question is whether the detour through 115vac is wasteful or not.
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On the internet, nobody knows you're a jerk.
 
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who where
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      02-09-2011, 12:03 AM
On Tue, 08 Feb 2011 13:47:59 -0500, Ron Hardin
<(E-Mail Removed)> wrote:

>Ron Hardin wrote:
>>
>> Any good suggestion for a 12v adapter for Dell laptops?
>>
>> In particular, how do you know what works on what models.
>>
>> Second, how efficient are they?
>>
>> Low wattage is a plus - the concern is to run the laptop as long
>> as possible on the 12v battery, and not to recharge the laptop
>> battery. Maybe taking the internal battery out takes care of
>> that?
>>
>> I assume that 12v to whatever DC-to-DC is more efficient than
>> going to a 115v inverter and the regular AC adapter, but maybe
>> not. Maybe the DC-to-DC already goes to an internal inverter
>> that's less efficient, who knows.

>
>60w solar array indoors (so it's getting much less than 1/3 power) on a
>dim sun day at noon can power an Inspiron mini 910, with a 60w cigarette
>lighter inverter.
>
>At least the 12v charge light on the 12v battery charge controller flicks
>on and off, which means the solar array is more than keeping up with the
>load on the battery.
>
>Which means that when the power goes out and the gasoline runs out, at
>least I can program, at least part of the day.
>
>The question is whether the detour through 115vac is wasteful or not.


It is wasteful, but the real question is whether the waste of running
though an inverter at say 85% and then the laptop's 90-plus percent
efficient PSU (i.e 75%-ish overall) is at any real cost to either you
or the planet.

Do the sums. The sunlight you intercept would otherwise fall on the
ground/floor and result in heating. The losses in your system result
in heating, and virtually all the energy your system uses is
dissipated as heat. Energy in = energy out.

The concept of wasteful could be applied to all the energy that could
potentially be intercepted and used, but isn't. Or to the money you
would otherwise waste by buying electricity from the grid.
 
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Ron Hardin
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      02-09-2011, 12:34 AM
who where wrote:
>
> On Tue, 08 Feb 2011 13:47:59 -0500, Ron Hardin
> <(E-Mail Removed)> wrote:
>
> >Ron Hardin wrote:
> >>
> >> Any good suggestion for a 12v adapter for Dell laptops?
> >>
> >> In particular, how do you know what works on what models.
> >>
> >> Second, how efficient are they?
> >>
> >> Low wattage is a plus - the concern is to run the laptop as long
> >> as possible on the 12v battery, and not to recharge the laptop
> >> battery. Maybe taking the internal battery out takes care of
> >> that?
> >>
> >> I assume that 12v to whatever DC-to-DC is more efficient than
> >> going to a 115v inverter and the regular AC adapter, but maybe
> >> not. Maybe the DC-to-DC already goes to an internal inverter
> >> that's less efficient, who knows.

> >
> >60w solar array indoors (so it's getting much less than 1/3 power) on a
> >dim sun day at noon can power an Inspiron mini 910, with a 60w cigarette
> >lighter inverter.
> >
> >At least the 12v charge light on the 12v battery charge controller flicks
> >on and off, which means the solar array is more than keeping up with the
> >load on the battery.
> >
> >Which means that when the power goes out and the gasoline runs out, at
> >least I can program, at least part of the day.
> >
> >The question is whether the detour through 115vac is wasteful or not.

>
> It is wasteful, but the real question is whether the waste of running
> though an inverter at say 85% and then the laptop's 90-plus percent
> efficient PSU (i.e 75%-ish overall) is at any real cost to either you
> or the planet.
>
> Do the sums. The sunlight you intercept would otherwise fall on the
> ground/floor and result in heating. The losses in your system result
> in heating, and virtually all the energy your system uses is
> dissipated as heat. Energy in = energy out.
>
> The concept of wasteful could be applied to all the energy that could
> potentially be intercepted and used, but isn't. Or to the money you
> would otherwise waste by buying electricity from the grid.


The trick isn't generating heat, but doing something with the energy before
it becomes heat.

It's an entropy minimization problem.
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On the internet, nobody knows you're a jerk.
 
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Nate Nagel
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      02-09-2011, 03:32 AM
On 02/08/2011 01:47 PM, Ron Hardin wrote:
> Ron Hardin wrote:
>>
>> Any good suggestion for a 12v adapter for Dell laptops?
>>
>> In particular, how do you know what works on what models.
>>
>> Second, how efficient are they?
>>
>> Low wattage is a plus - the concern is to run the laptop as long
>> as possible on the 12v battery, and not to recharge the laptop
>> battery. Maybe taking the internal battery out takes care of
>> that?
>>
>> I assume that 12v to whatever DC-to-DC is more efficient than
>> going to a 115v inverter and the regular AC adapter, but maybe
>> not. Maybe the DC-to-DC already goes to an internal inverter
>> that's less efficient, who knows.

>
> 60w solar array indoors (so it's getting much less than 1/3 power) on a
> dim sun day at noon can power an Inspiron mini 910, with a 60w cigarette
> lighter inverter.
>
> At least the 12v charge light on the 12v battery charge controller flicks
> on and off, which means the solar array is more than keeping up with the
> load on the battery.
>
> Which means that when the power goes out and the gasoline runs out, at
> least I can program, at least part of the day.
>
> The question is whether the detour through 115vac is wasteful or not.


I'm sure it has to be.

I have a Rocketfish (house brand for Best Buy AFAIK) AC/DC power supply.
It powers my Studio 1555 just fine, but if I tried to boot my old
Precision M90 off of it I'd get a power supply error. I'd have to boot
it on battery and then plug the PS in. Works fine inside the house or
in the car. Don't know if it is more efficient than using an inverter
and the stock brick, but it seems as though it would be. Now you have
me curious and I am tempted to rig a test somehow. It's certainly
lighter and less cumbersome than the inverter that I used to keep in my car.

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel
 
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who where
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      02-09-2011, 12:00 PM
On Tue, 08 Feb 2011 19:34:03 -0500, Ron Hardin
<(E-Mail Removed)> wrote:

>who where wrote:
>>
>> On Tue, 08 Feb 2011 13:47:59 -0500, Ron Hardin
>> <(E-Mail Removed)> wrote:
>>
>> >Ron Hardin wrote:
>> >>
>> >> Any good suggestion for a 12v adapter for Dell laptops?
>> >>
>> >> In particular, how do you know what works on what models.
>> >>
>> >> Second, how efficient are they?
>> >>
>> >> Low wattage is a plus - the concern is to run the laptop as long
>> >> as possible on the 12v battery, and not to recharge the laptop
>> >> battery. Maybe taking the internal battery out takes care of
>> >> that?
>> >>
>> >> I assume that 12v to whatever DC-to-DC is more efficient than
>> >> going to a 115v inverter and the regular AC adapter, but maybe
>> >> not. Maybe the DC-to-DC already goes to an internal inverter
>> >> that's less efficient, who knows.
>> >
>> >60w solar array indoors (so it's getting much less than 1/3 power) on a
>> >dim sun day at noon can power an Inspiron mini 910, with a 60w cigarette
>> >lighter inverter.
>> >
>> >At least the 12v charge light on the 12v battery charge controller flicks
>> >on and off, which means the solar array is more than keeping up with the
>> >load on the battery.
>> >
>> >Which means that when the power goes out and the gasoline runs out, at
>> >least I can program, at least part of the day.
>> >
>> >The question is whether the detour through 115vac is wasteful or not.

>>
>> It is wasteful, but the real question is whether the waste of running
>> though an inverter at say 85% and then the laptop's 90-plus percent
>> efficient PSU (i.e 75%-ish overall) is at any real cost to either you
>> or the planet.
>>
>> Do the sums. The sunlight you intercept would otherwise fall on the
>> ground/floor and result in heating. The losses in your system result
>> in heating, and virtually all the energy your system uses is
>> dissipated as heat. Energy in = energy out.
>>
>> The concept of wasteful could be applied to all the energy that could
>> potentially be intercepted and used, but isn't. Or to the money you
>> would otherwise waste by buying electricity from the grid.

>
>The trick isn't generating heat, but doing something with the energy before
>it becomes heat.


Exactly. The energy is a pass-through, but it's nbice to get some use
as it passes.

>It's an entropy minimization problem.

 
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