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I am new to SFF computing. I live on a 40' sailboat with a large solar array and lots of 12V batteries. While sailing the computer receives data from the GPS, runs a real time navigation system, and provides control data to an autopilot. The system will run 24 hours a day while underway with only solar power (~480watts) to recharge the batteries (550 amp hours).

I know the max current draw for most components in the box. What I don't know is the average current consumption, watts or amps, while running a single program that writes a disk record every five minutes and receives GPS data every 5 seconds.

The SB51G will have a slow P4, 512MB, 60GB HD, CDRW/DVD installed. There is a 17" LCD and a wireless keyboard but I know the current draw for those components.

QUESTIONS:
1) What is the average long term current draw for the system I describe?

2) I will use a 300 watt modifed sine wave inverter to power the system. Will the SB51G powersupply be damaged by a modifed (square) sine wave?

Sailor wrote:

I am new to SFF computing. I live on a 40' sailboat with a large solar array and lots of 12V batteries. While sailing the computer receives data from the GPS, runs a real time navigation system, and provides control data to an autopilot. The system will run 24 hours a day while underway with only solar power (~480watts) to recharge the batteries (550 amp hours).

I know the max current draw for most components in the box. What I don't know is the average current consumption, watts or amps, while running a single program that writes a disk record every five minutes and receives GPS data every 5 seconds.

The SB51G will have a slow P4, 512MB, 60GB HD, CDRW/DVD installed. There is a 17" LCD and a wireless keyboard but I know the current draw for those components.

QUESTIONS:
1) What is the average long term current draw for the system I describe?

2) I will use a 300 watt modifed sine wave inverter to power the system. Will the SB51G powersupply be damaged by a modifed (square) sine wave?

Welcome to TR.

All power supplies have their tolerances, and unless someone knows something I don't, there hasn't been much testing in regards to dirty power. I believe it should handle MSW power fine, as most UPS backups wil output MSW power.

I had a teacher who lived on a yacht to avoid paying property tax. Same deal?

If you're worried about the power supply, just stick a small but active PSU in between. Something that conditions the power would correct any problems you might have.

Mac,

Two things to consider. Cadalic XPC. Apparently a boffin in the States has place a SN41G2 in his Caddy. There was a story on the inquirer about this three weeks ago.

Secondly 12DC direct imput is in more efficent and will result in a more stable system.

Why?

I was running my laptop on a farm last year with out main power. We had a small but adequate solar system which power lights, fridge, and two laptops.

One laptop we ran directly of 12Volts through a Targus voltage controller adapter (http://www.targus.com) This system was fantastic, the power was allways stable and the computer ran perfectly. The second system we ran through a 12DC to 240AC inverter. This system was terrible. The inverter just didn't supply a clean enough voltage. Running either computer on this system, resulted in regular crashes.

I would suggest that you look out for the ZEN XPC. This comes with an external power supply. It would then be a simple matter of buying a voltage conditioner (something like that targus gadget, to protect your system for surges and what not.)

Remember to post picture when you are done.

Sailor, have you considered just trading the system you have and getting a notebook to run directly off the 12v without any mods? It would seem to me that would be more efficient as you would not be losing 30% or more of your power going from 12-120-12. Any decent notebook would use less power, and have all the computing power you are going to need as well as being portable, and having low power built in display.

I have lived on my boat in Western Mexico for the last two years. We follow the 85 degree temperature line, going as far south as Acapulco during the winter and as far north as Puerto Refugio (north end of Isla Angel de la Guarda) during the summer. That's about 1100 nautical miles.

What is the "Targus voltage controller adapter" - I visited the Targus site and found only 12V-19V adapters and inexpensive inverters. I currently have two Targus 12V-19V adapters on the boat. I also have a 300 watt inverter and a 2kW inverter.

Are you suggesting I rewire a SFF box, e.g Shuttle, to run directly off the boats 12V (actually 12.4 to 14.4V) power? if so - how would I do that? The boats batteries are high amp storage devices but the voltage available on the main bus at the breaker panel varies from 12.4 to 14.4. Would that variability hurt the alternate powersupply (Boat DC to 3.3,5,12V in the Shuttle)?

I have been using laptops on Mirador (my boat - visit http://www.svmirador.net to see thousands of pages of writing and pictures) for nine years. The problem with laptops is that I can not repair them at the board level. I keep the laptops in dry (no splashing water) but the ambient atmosphere can be very damp. In Mexico the ambient temp is 85 to 105 degrees with humidity varying from 15% to 99%.

The laptops develop corrosion fingers on the boards within 12 to 18 months and are way too expensive to repair. I am thinking that I can repair an SFF PC at the board level for a lot less than a laptop.

Sailor wrote:

Are you suggesting I rewire a SFF box, e.g Shuttle, to run directly off the boats 12V (actually 12.4 to 14.4V) power?

no, I was refering to 12V being the common native power for notebooks.

Sailor wrote:

The laptops develop corrosion fingers on the boards within 12 to 18 months and are way too expensive to repair.

You have more experience with this type thing than I do. Looks like you will have to find a way to treat the corrosion with maintenance or seal the board. If you go the sff route, you will have the additional circuitry of the dc-ac inverter to deal with as far as corrosion. You might want to contact some experienced marine electronics installers and chat with them. Their experience is bound to have some valuable information.

Holy crap! Living on a boat would be amazing! But what do you do for a living? How can you afford to do this full time? It must be very expensive...

You could dig around, I've seen 1U power supplies that have been used in car m3 players that run on 12V DC. A laptop is also a good idea prices on them have dropped like a rock lately and you get all the power-saving goodness built into them as well. Also think about MiniITX boards. The Casetronic 2699R cases have 12V PSUs built in.

http://www.mini-itx.com for a ton of info in that direction