Cigarette Lighter Adapter- Cessna 172

On Fri, 04 Aug 2006 16:01:01 -0400, Stubby
wrote:



Grumman-581 wrote:
On Fri, 4 Aug 2006 09:29:32 -0400, "Morgans"
wrote:
...

Most of the ones that I've seen have around 90% efficiency, sometimes
even more...
It has been many years since I was a circuit designer but I seem to
remember some theoretical limit on the efficiency of a static inverter
at 83%. This was caused by the energy lost in the transformer assuming
perfect switches (power transistors).

For the last several years, all the new converters, ac/dc and dc/dc
have been switchers. For ac/dc, there are requirements that in
standby modes or open-circuited they consume no more than half a Watt.
Dc/dc switchers, from tens of watts, down to milliwatts (Your
cellphone can have as many as ten separate power rails.) do better
than 90% peak efficiency. Up to 3 A, they often integrate the
switching FETs.

But no gear draws peak power all the time. Unfortunately for the
power supply designer, supplies have to be able to deliver peak power
almost instantly.

Don

Morgans wrote:
"Andrew Sarangan" wrote

I have an inverter that I bought for $19.99. It has a 150W contunuos
power rating. It runs my laptop just fine. Why do you need 1000W?

My son has a whopper computer he uses for video editing and stuff, and when
it cranks up, it really sucks the power.

I have a DELL XPS GEN II laptop. Up until DELL's latest 20" behemouth
it was the largest laptop on the market. It sucks 90 watts from the
power supply. As a result, you can't get seat power for it (which
is limitted to 75).

Grumman-581 wrote:
On Fri, 4 Aug 2006 09:29:32 -0400, "Morgans"
wrote:
Do you have any idea how much power that would require, and the cost of the
inverter for a good sized, powerful laptop computer?

Looking at Grace's new laptop, I see a power supply rating of 100V at
1.6A, thus a 160W maximum draw...

I'd really be surprised. Most smaller notebooks are in the vicinity
of 60W really. Even the biggest ones only draw 90 from the DC
side.

On Fri, 04 Aug 2006 21:10:58 GMT, B A R R Y
wrote:

The weird thing about the Toyota inverter is that it's capable of a
higher draw when the truck is idling vs. running at highway speed.
They also install an inverter in the Matrix, but the outlet is in the
dash vs. my bed outlet.

Sounds possible but will depend on what you're running.

If you draw the same output load you need to supply the same input.
If volts go down then amps need to rise since Power = Amps x Volts.

e.g. If you draw say 80 watts output all the time (assuming 80%
efficient) you will need to supply 100watts input.

When running the engine the battery will be charging at around 14
volts so will supply 100/14 = 7.1 amps.

At rest a 12v battery will have to supply 100/12 = 8.3 amps
If the battery is less than 12 volts it will be even higher.

"RST Engineering" wrote in message ...
:I don't mean to be pedantic, but you can't "transform" a DC voltage;
: transformers only work on AC. Do they use a center tap on the battery or a
: regulator? If they use a regulator, it had damned well better be a hefty
: one to take the slug of current that a cigarette lighter draws.
:
: Jim
:
:
:

Don't they use a voltage divider of some sort?

"Ron Natalie" wrote in message
m...
Grumman-581 wrote:
On Fri, 4 Aug 2006 09:29:32 -0400, "Morgans"
wrote:
Do you have any idea how much power that would require, and the cost of
the
inverter for a good sized, powerful laptop computer?

Looking at Grace's new laptop, I see a power supply rating of 100V at
1.6A, thus a 160W maximum draw...

I'd really be surprised. Most smaller notebooks are in the vicinity
of 60W really. Even the biggest ones only draw 90 from the DC
side.

I'll have to wait for my son to get home, and I'll post what his power
supply is rated at. You will be surprised! g
--
Jim in NC

OK, it's a 'converter'. Not sure exactly what method it uses to
'convert'.

182T Nav III POH, section 7-73,

"12V POWER OUTLET

A power converter located in the cabin side of the firewall, ahead of
the right instrument panel, reduces the aircraft's 28 VDC power to 12
VDC. This converter provides up to 10 amps of power to operate
portable devices such as notebook computers and audio players. The
power output connector (POWER OUTLET 12V -10A) is located on the
center pedestal (refer to Figure 7-2)."

Usual disclaimer about 'see your own aircraft POH for amperage
available etc' applies, but it's also the same in the 172S Nav II and
III packages I've had experience with.

Newer 182T's (2005? and on - I've seen it in an 06) actually have a
rear-seat-mounted cabin power in addition to the one in the front with
it's own on/off switch on the main panel. I wonder if they mounted a
second 'converter' to handle that outlet or if they share somehow. I
was only ferrying it for maintenance and didn't look too closely.

On Thu, 3 Aug 2006 20:05:39 -0700, "RST Engineering"
wrote:

I don't mean to be pedantic, but you can't "transform" a DC voltage;
transformers only work on AC. Do they use a center tap on the battery or a
regulator? If they use a regulator, it had damned well better be a hefty
one to take the slug of current that a cigarette lighter draws.

Jim



"Peter Clark" wrote in message
.. .
All the new (since the line started back up) 172R/S models have
transformers. The outlets are 12V.

October will be 2 years off cig's cold turkey from 3 packs for me!

On Fri, 04 Aug 2006 22:11:47 GMT, B A R R Y
wrote:

On Fri, 04 Aug 2006 23:03:21 +0100, wrote:

On Fri, 04 Aug 2006 21:10:58 GMT, B A R R Y
wrote:

The weird thing about the Toyota inverter is that it's capable of a
higher draw when the truck is idling vs. running at highway speed.
They also install an inverter in the Matrix, but the outlet is in the
dash vs. my bed outlet.

Sounds possible but will depend on what you're running.


It has nothing to do with what I'm running. The manual states, and
the indicator lights will demonstrate, that the inverter swaps limits
depending on engine RPM. The dash switch actually has two output
status lights, and will flick back and forth as you drive if the
inverter is energized, even without a load.

By running I was refering what load you are running from the inverter.