'mobile' PC power source

[jumpthewire]

Hello,
I'm new to PC Guide (where was it when I really needed it?) and new to forum-type-things ( I once joined one to ask how to get rid of bitch urine marks on a lawn and had 50,000 american matrons post replies, I never did find out, just replaced the lawn with gravel!).I plan to retire to the Mediterranean soon and for a variety of reasons want to install a PC in an RV and then into a boat or both.

Each/either 'vehicle' will have 12 Volt DC power, with plenty of battery power and a generator and probably an inverter for 220-240 volts AC 50Hz. But ,of course, 'shorepower' on campsites or marinas.

But it seems daft to me that I run a PC which internally uses low voltage, from an inverter to get 220-240V then the PC drops it back to 5V!!! The question is, "Can I use a step down transformer, say, depending on which PC I buy - 5 volt, from the Battery bank at 12-14 volts? (I bought my current laptop purely because its 12 volt, and used it 'aboard' succesfully re-charging from the boats battery supply at times when the engine was off, to protect it from higher voltages.)

Also, please, "Where would the DC connections go, presumably by-passing the PSU?"

There was some talk on another thread about 350 Watts of demand, surely thats 30 Amps 12Volt /70Amps @ 5V, so how can the board stand it? Are there normally any other different voltages sourced from the 'mains socket' on a PC that power separate 'bits' in the case such as CD drives etc?

[david eaton]

You need the internal PSU. Computers have several different voltage rails, +3.3v ,5v,+12V, -12V, -5V.
It seems wasteful to convert 12 voltsDC to mains AC, only to step it down again, but it is the easiest way, unless you use the 12 volt input on your laptop.
Using it from a vehicle/boat electrical system at 12v, it doesn't really matter if the engine is running or not, as the internal converter offers protection from overvoltage up to about 13.5-14 V. Check your manual to be certain.

David

[saphalline]

It seems to me you might be able to construct your own power supply, but that would be the job of an electrician (or yourself if you're really brave). It is wasteful to convert DC power to AC then back to DC for a computer, so if you can keep the DC, that would be preferable...

One problem is in the fact that a computer's PSU is not a direct-line contact with an AC/DC converter in between. The PSU is an active electrical system capable of overvolt protection (like david eaton said) as well as some line conditioning and most importantly: grounding.

The info on exactly what makes an ATX 2.03 spec PSU is most surely available for free on the internet, but like I said, you'd need to be an electrician or a quick study in order to make it work on a boat that already supplies DC. The other thing to keep in mind is that directly wiring your PC to a boat's DC output would probably void your PC's warranty. And if an electrical problem with your non-standard PC fried your boat's electrical system, your boat's warranty might be fried, too.

The numbers and current direction add up, but safety and warranties come first in my book.

[Reid]

There are DC to DC power supplies available. Here is one link, for example: http://www.orbitmicro.com/products/power%20supplies/dc-dc%20ps2.htm

Try a Google search to see if there are UK distributors (and perhaps lower prices).

[jumpthewire]

I'm much obliged for the advice, and sense prevails; I will use inverters! Or an abacus. :rolleyes: