running 19V input rated motherboard from 12V DC battery directly

[anton.p45]

Hello, has anyone tried running 19V input thin mini-itx motherboard from 12V battery directly, without use of DC-DC converter?
I have H81TN board with mSATA drive and nothing plugged into internal 12V rail (no HDD) except CPU fan. Since CPU needs 1V and everything else should be 3.3 - 5V, internal DC converters should not care if they see 19V or 12V on their inputs. The only problem might be with 19V - 12V converter that may shut down due to input voltage being too close to it's output.

I tried contacting Gigabyte tech support, but they are basically clueless, and could only recommend me a 19V AC-DC adapter. 

I would like to see if anyone else tried this before I try this on my board (and possibly damage it).

[autotech]

The main problem I see with your idea is you are using 12v DC.  If you had a way to turn it into AC it might possibly work. I say possibly because the PSU converts your power down to 3.3 and 5v . Now the motherboard connector does use the 12v rail but again it is the PSU that converts it.

I am sure your PSU in that uses 120v AC. You would have to find a way to convert your 12v direct current into what the PSU needs which is 120v AC.
Now if you are deleting the PSU and directly hooking it up to the motherboard you need to convert it to AC no matter what.

[anton.p45]

Hi autotech,

I am using Gigabyte H81TN thin mini ITX board (http://www.gigabyte.com/products/product-page.aspx?pid=4752#ov) that uses only 19V DC input, like laptops do. It does not have 24pin ATX power connector like regular full size motherboards. So it makes 1.2V, 3.3V, 5V and 12V on the board itself out of 19V input.

The reason for this project is that I want to run this board from 12V DC battery charged from solar panel. I would like to avoid using additional 12V to 19V step-up DC converter to avoid efficiency losses associated with it.

[autotech]

ok I looked at specs before but didn't look at picture. It also says thru a switch on board it can switch to just 12 volt. So you don't if I understand rightly have to use 19 volt.

Offering additional flexibility for system DC voltage input, GIGABYTE Thin Mini-ITX motherboards offer a broad voltage range of 12v to 19v, eliminating compatibility issues with many traditional IPC designs.

If it was me I would try the 12 volt and make sure switch was set to it. Otherwise you would have to have an amplifier to go to 19 volt.  That doesn't have to be store bought if I needed 19 volts out of a car battery id put a gather in it so it would gather to 19 volt and on the other side of that I would put a 1 way diode so there was no chance of power backlash.  I know I can get diodes from radio shack. the booster is going to more like a car module printed circuit board.

http://www.ti.com/lit/ds/symlink/tps40210.pdf

Or look at these options from ebay

http://www.ebay.com/itm/150W-DC-DC-Boost-Converter-10-32V-to-12-35V-6A-Step-Up-Voltage-Charger-Power-/370766558750?pt=LH_DefaultDomain_0&hash=item565368b61e

http://www.ebay.com/itm/DC-12V-to-19V-4A-76W-STEP-UP-DC-DC-Power-Converter-Regulator-/290822881442


I hope this helps if I am still misunderstanding post back maybe someone with more know how than me can help out.