Converting desktop LCD monitor to 12v???

[Charlie Wilkes]

I live off the power grid and am itching to build a 12 volt mini-itx
desktop system that is energy efficient.

The catch is that 12v LCD monitors, designed for automotive applications,
are VERY expensive ($300 for a 15" unit).

Don't the standard desktop LCD monitors convert AC grid power to 12v DC
anyway? How hard would it be to hack one of these units to run directly
from a 12v power source?

All advice and comments welcome. Thanks.

Charlie

 

[Paul]

I live off the power grid and am itching to build a 12 volt mini-itx
desktop system that is energy efficient.

The catch is that 12v LCD monitors, designed for automotive applications,
are VERY expensive ($300 for a 15" unit).

Don't the standard desktop LCD monitors convert AC grid power to 12v DC
anyway? How hard would it be to hack one of these units to run directly
from a 12v power source?

All advice and comments welcome. Thanks.

Charlie

My LCD monitor has a separate wall wart, and it converts 115VAC to
12VDC at 4 amps max. The monitor uses 3 amps max, and probably
a bit less than that. So my LCD would be a good candidate
for your project. There are also LCDs that integrate the
power into the base of the monitor, and those would not be
a good candidate for your project. So you're looking for a
monitor that uses a wall wart, as the most likely solution.

You can see in this picture, for example, that an external
power supply is used. This is just the first one I found in
the Newegg collection.

http://images10.newegg.com/NeweggImage/productimage/24-005-035-07.jpg
http://www.newegg.com/Product/Product.aspx?Item=N82E16824005035

The tough part, will be converting from your unregulated battery
voltage (13.2V perhaps) to the 12V the monitor is expecting.

Here is an example of a module to convert from your battery,
to drive the LCD. Some connector surgery will be
required, plus the addition of a switch, to disconnect the
battery when you are not using the monitor.

DC-DC Regulator Module : 10-17VDC to 12VDC 4 Amp $14.95 (not in stock)
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2494

Note that the above regulator module, is probably not an "isolating"
type. The wall wart that comes with the LCD is isolating, meaning the
AC power rails and the DC outputs are not connected in any way. When
you use the above 10-17VDC to 12VDC converter, that is probably
a buck converter, with a common ground. That means the ground of
your battery system, also is the ground of the monitor, the monitor
VGA shell will also be at the battery ground potential. This is fine
if the computer is also grounded the same way. There are also regulator
modules that will fully isolate the output (the same way that an
ATX power supply does), but they will likely be a few dollars more.

Paul

 

[Charlie Wilkes]

You can see in this picture, for example, that an external power supply
is used. This is just the first one I found in the Newegg collection.

http://images10.newegg.com/NeweggImage/productimage/24-005-035-07.jpg
http://www.newegg.com/Product/Product.aspx?Item=N82E16824005035

The tough part, will be converting from your unregulated battery voltage
(13.2V perhaps) to the 12V the monitor is expecting.

Here is an example of a module to convert from your battery, to drive
the LCD. Some connector surgery will be required, plus the addition of a
switch, to disconnect the battery when you are not using the monitor.

DC-DC Regulator Module : 10-17VDC to 12VDC 4 Amp $14.95 (not in stock)
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2494

Note that the above regulator module, is probably not an "isolating"
type. The wall wart that comes with the LCD is isolating, meaning the AC
power rails and the DC outputs are not connected in any way. When you
use the above 10-17VDC to 12VDC converter, that is probably a buck
converter, with a common ground. That means the ground of your battery
system, also is the ground of the monitor, the monitor VGA shell will
also be at the battery ground potential. This is fine if the computer is
also grounded the same way. There are also regulator modules that will
fully isolate the output (the same way that an ATX power supply does),
but they will likely be a few dollars more.

Excellent. You have provided exactly the information I wanted. Thank
you very much.

Charlie

 

[Paul]

Excellent. You have provided exactly the information I wanted. Thank
you very much.

Charlie

To verify the external module is a 12V one, you can download the manual.
For example, the manual for the above monitor is here:

http://us.lge.com/download/product/file/1000000392/L1780U.PDF

It does mention 12V @ 3A on page 20 of the manual. I would expect 12V
to be a popular voltage, but for your peace of mind, it might be
easier to examine the product in a local store, to verify it is powered
the way you want it to be. The pictures on Newegg aren't clear enough
to verify the design of the AC adapter.

Paul

 

[Franc Zabkar]

The tough part, will be converting from your unregulated battery
voltage (13.2V perhaps) to the 12V the monitor is expecting.

The hard disc and optical drives would require a regulated +12V
supply. If this rail has enough spare capacity, then perhaps the OP
could use it for the monitor, assuming the monitor's signal and power
grounds are common.

- Franc Zabkar