HowToFixComputers.com

W. Watson · Guest

Is it possible to somehow tap into the auto battery of my car to power my
laptop?
--
Wayne Watson (Nevada City, CA)

Web Page: <speckledwithStars.net>

mike · Guest

W. Watson wrote:

W. Watson · Guest

I only plan to use it when the vehicle is not running. In other words, when
I'm through driving for the day. What do I need to successfully use the
battery? Some sort of divider?

mike wrote:

Salvador Freemanson · Guest

W. Watson wrote:

Val · Guest

google for: auto power adapter laptop

you will find lots of adapters that plug into the lighter, provide power to
the laptop. You may find a model specifically for your laptop, as well as
many generic versions.

Alternatively, you could get a DC/AC inverter that will create 110V AC,
which you then plug your normal laptop powerpack into.

Val

paulmd@efn.org · Guest

On Jun 4, 7:32 pm, "W. Watson" <wolf_tra...@invalid.com> wrote:

W. Watson · Guest

There still remains the question of the inconsistent frequency if one uses
an inverter to produce AC, and then plugs the laptops adpater into it. Maybe
it has no impact at all on the HD or other components.

Has anyone actually used a laptop in this way and found that after six
months the laptop is doing just fine. I talked to a sales guy at Best Buy
and he said that's exactly what he was doing, but he was not just doing it
when the motor was off. He puts his laptop in the passenger's seat and runs
it with an inverter. I guess he gets lots of music from his laptop that he
might not get. He admitted that he's only done this a handful of times, so
he hardly meets the six month requirement I posed above.

Barry Watzman wrote:

Barry Watzman · Guest

The frequency of an inverter in this application has no impact. The
laptop's AC adapter/charger is a switching power supply. The first
thing it does is take the incoming line voltage, run it through a full
wave rectifier and then crudely brute force filter it with some
capacitors to a rough, high-ripple DC. Frequency is irrelevant. In
fact, almost everything is irrelevant ... noise and (over a very wide
range) voltage included.

If there was any risk, it would primarily be to the laptop's AC adapter
rather than the laptop itself.

W. Watson wrote:

Salvador Freemanson · Guest

Barry Watzman wrote:

Barry Watzman · Guest

They are connecting equipment that was intended to be so directly
connected ... that has power supplies inside it that are tolerant of
this environment. It's certainly possible to design equipment to
tolerate this, all automotive electronics does it.

But a laptop computer was not designed to operate this way. A laptop
that was intended for this application could certainly be designed, but
that's another matter.

none wrote:

Barry Watzman · Guest

It's not waste free at all. The voltage is dissipated in the transistor.

I repeat my original post:

THERE ARE ONLY TWO WAYS TO CHANGE ONE DC VOLTAGE TO ANOTHER:

1. Convert it to AC, change it, and convert it back to DC.

2. ***IF*** the input voltage is higher than the desired voltage, you
can just "waste" the excess voltage as heat. This is VERY inefficient,
but it does work. It's not even an option, however, if you have 12
volts and you need, say, 15 volts.

The second way is what ALL "linear regulators" and "linear power
supplies" do. It takes a switching power supply to do it the first way,
which is actually far, far more efficient and is the only way to simply
not waste ALL of any "excess" voltage as heat.

Salvador Freemanson wrote:

none · Guest

W. Watson · Guest

Good. Thanks.

To just clarify for all what I was driving at (aside from frequency), what I
didn't want was:

(DC-car)]---inverter---[(AC/120)]---converter---[(DC-laptop) ]{laptop}

the [ and ] are plugs/sockets. {} is the laptop itself. --- is wire.() is
the voltage type, e.g., (AC).

What I wanted was:

(DC-car)]---dc/dc---[(DC-laptop)]{laptop}

I hope the figures are clear. Simply, one dc/dc adapter was what I wanted.

The reason I was concerned about a stable frequency was that several years
ago, I was concerned about protecting our household power in the event of an
outage. A simple solution was to have a big 12v/dc battery and hook up an
inverter to it, then plug a desktop into it. I read that a stable frequency
was a concern in that case.

Is there a name for the dc/dc adapter? Voltage booster?

I understand that decades ago that cross-country power used AC (Tesla), but,
in the decades that produced silicon devices, AC went into the grid only to
be converted to dc for cross-country transmission. At the other end, it was
back to AC from the DC. I suspect what you are saying is something close to
the same idea.

Barry Watzman wrote:

Barry Watzman · Guest

Just from the physical size of that unit I would guess that it's output
is 60 watts or less (it's actual power output, without regard to any
claims that may be made). You can charge a battery with that, but you
may not be able to run a laptop.

Salvador Freemanson wrote:

Barry Watzman · Guest

I find that hard to believe, for ANY power transmission application. At
some point, you need to step it down, and you can't do that with DC.
Further, there is no inherent transmission advantage to DC vs. AC, and
on top of that DC is hard to generate from a mechanical generator.

PJ wrote: