Best way to power onboard computer?

chal

chal

Well-Known Member
Joined
13 Jul 2010
Messages
581
Location
Valentia Island, Kerry
Visit site
I've built a computer to replace an old laptop on board. It's made up from mini-itx components which should make it ideal for a boat as it uses very little power and runs off 12V. I've tried it at home via a 12V mains power adaptor and it works fine. On board, I can't get it to work at all. It once got as far as displaying an error message about thermal cutout but this was probably wrong as it had only been running for maybe a minute. Mostly it switches off within a few seconds before producing any error message, or indeed anything on screen.

I've tried using it via a device that's supposed to smooth out the voltage in a car. I have one each for the computer and the monitor; neither seemed to work properly so I assume that though the regulators were quite expensive they aren't much good.

I've tried using it with an inverter: seems a bit wasteful to go from 12V to 240V so that I can then plug my 12V adaptor in, but if that's the only way, it would do. The screen works fine, but the computer still just cuts out, too quickly to be able to establish exactly why. It's only a very cheap ebay inverter, though it claims to be able to manage 150W and the mains adaptor is only rated at half that (and the computer itself shouldn't really use more than about 20-30 watts).

I'm sure there are lots of other people running computers out there: how?

Incidentally, I've noticed that if I try to run the old laptop via its mains adaptor plugged into one of the inverters, it's not very happy either. I can use it by switching it off and letting the inverter charge the battery, then disconnecting it and running it, but if I try while it is plugged in it keeps reporting that the mains has been disconnected, then connected, then disconnected, etc. I assume the inverter is failing to produce a steady enough supply, so maybe all that is happening when I use it with the computer is that it starts to boot, then cuts out the instant the power drops, whereas the drop isn't sufficient to bother the monitor. Is this a property of inverters in general? Or only of cheap ones? I don't really want to have to buy an expensive one since that's not how I really want to run the computer.
 
Well, the nominal 12 volt supply on a boat can easily vary between about 11 and 14.5 volts, depending on the state of charge of the battery. So if you're depending on an exact 12 volts, you're very unlikely to get it, and that could cause all sorts of strange effects, as you have noticed.

Not comparable, but I use a Dc to DC power supply to run lap-tops; they mostly use 18 volts, and most electronics stores have them for a variety of power outputs. It sounds daft, but using one in 12v to 12v mode might well work.

Concerning your laptop, what sort of output does your inverter produce? If it isn't sine wave, then you could have problems with any kit expecting sine wave, and that might well include the AC to DC adapter.
 
If you're powering it from a cigar lighter socket, check the voltage at the socket with and without the computer plugged in. If it's significantly lower with the computer plugged in, you need to upgrade the cabling to a bigger SWG right from the battery to the computer.
 
Check what voltage the 12volt mains adapter really is putting into your computer. You would need to check it under load (not just the open circuit voltage).

Does it make any difference if you try the computer on the boat with the engine running?

Have you tried running the computer from your car cigar lighter socket? If it works then you've got a pointer.
 
Trouble is that, as others have said, the so-called 12v in a boat (or car) is not regulated in any particular way and can swing about quite a lot. For good regulation, the power supply needs a few spare volts to play with, so you are always going to have an inverter involved - either a 12v to mains voltage AC inverter, or the black-box inverter that is hidden away inside a 12v input regulated computer power supply.
 
There are proper vehicle power supplies for this application, I'll dig out a link in a few mins when on main PC
 
I too have tried a 12 volt supply to a computer rated at 12v, without usable success, so after testing my Wife's Asus netbook on board, powered via the 12volt supply, I purchased a refurbished one for about £100, it works fine. I have also removed the battery to test if it will work just with boat supply, it does, I would just say, I have a total AH of 240 in deep cycle 6volt batteries, these are kept topped up by a combination of a Rutland 913 and 2 solar panels pushing out, on a good day 160AH. Perhaps the best thing that can be said regarding a netbook is that it does have a screen!!
 
I too have been trying to run a 12v low powered computer from the boat supply.
I found that all worked well until the supply voltage increased to about 13.25 or so and the computer shut down. It wouldn'd restart until the voltage dropped to about 13.
I have invested 20 squid on an Ebay miracle that is presently going under the item number :- 181144592755
It runs my setup OK both from 240v and also from the boats "12v" supply.
I have it coupled up to both at the same time so if one should fail the other does the business.
Might be worth a look.
Good luck.
 
robspop said:
I've built a computer to replace an old laptop on board. It's made up from mini-itx components which should make it ideal for a boat as it uses very little power and runs off 12V. I've tried it at home via a 12V mains power adaptor and it works fine. On board, I can't get it to work at all. It once got as far as displaying an error message about thermal cutout but this was probably wrong as it had only been running for maybe a minute. Mostly it switches off within a few seconds before producing any error message, or indeed anything on screen.

I've tried using it via a device that's supposed to smooth out the voltage in a car. I have one each for the computer and the monitor; neither seemed to work properly so I assume that though the regulators were quite expensive they aren't much good.

I've tried using it with an inverter: seems a bit wasteful to go from 12V to 240V so that I can then plug my 12V adaptor in, but if that's the only way, it would do. The screen works fine, but the computer still just cuts out, too quickly to be able to establish exactly why. It's only a very cheap ebay inverter, though it claims to be able to manage 150W and the mains adaptor is only rated at half that (and the computer itself shouldn't really use more than about 20-30 watts).

I'm sure there are lots of other people running computers out there: how?

Incidentally, I've noticed that if I try to run the old laptop via its mains adaptor plugged into one of the inverters, it's not very happy either. I can use it by switching it off and letting the inverter charge the battery, then disconnecting it and running it, but if I try while it is plugged in it keeps reporting that the mains has been disconnected, then connected, then disconnected, etc. I assume the inverter is failing to produce a steady enough supply, so maybe all that is happening when I use it with the computer is that it starts to boot, then cuts out the instant the power drops, whereas the drop isn't sufficient to bother the monitor. Is this a property of inverters in general? Or only of cheap ones? I don't really want to have to buy an expensive one since that's not how I really want to run the computer.
Click to expand...

I've used computers on board for >10years. Always laptops via a solid state transformer. Seems to me people are trying to re-invent a square wheel.
 
I have had good results using a Maplin "car charger" which can be set to various voltages, but, like AntarcticPilot, I've needed 16 or recently 19 volts. N.B. I found that going via a mains inverter consumed twice as much current, and in a previous thread others reported even worse inefficiency. Of course that is me stuffing it into the charger hole in a laptop, and there must be all sorts of modulating stuff between that and the actual supply to the computer.

One thing - to your "overheating" message. I suppose it is possible that, if you are applying 13 volts when it is expecting 12 that might manifest itself in overheating. (12 volts is actually low for a lead acid battery - expect more than that most of the time.) In an unrelated problem, I had trouble with a laptop failing with symptoms of overheating. Like you, I thought it was talking nonsense as it would fail within seconds of startup, surely not time to overheat. I took it to Sony (it is a Viao) for repair, and their man said that the processor could overheat and shut it down in seconds which I doubted. He found that the thermal cement from mother-board to heat sink had failed. He recemented it and the problem went away, so it seems he was right. I.e., I can imagine you might have an overheating problem created by too high a voltage. However, if you are a builder of computers you probably know mare about this than me!
 
I assume the fleabay inverter is a quasi sine type, and that'll be the inverter problem.

Some combinations of quasi sine and pc work fine, others don't.
You really need a pure sine inverter.
 
Buy a 12volt UPS (uniterrupted power supply) unit for 12 volt maintains voltage and acts as a battery back up too when going from shore power to boat etc. the boat im on was kitted out with one but not a 12volt system, we go through an inverter up to 230v then back down to 12v or less for the coumputers via the psu.s very poor design
 
I've used computers on board for >10years. Always laptops via a solid state transformer. Seems to me people are trying to re-invent a square wheel.
Click to expand...


I've used and worked with and programmed and built computers for nearly 30 years. This one runs a specialised operating system and software that I need for my work, and drivers for these sorts of things are often not available for laptops. I also use it to run a large, low power consumption screen that I can watch films on with pleasure. Seems to me that only sticking to laptops is working with a triangular wheel when you could have a round one if you wanted, even if it takes a bit more effort in the first place.
 
I have come to the conclusion that the best computer to have on a boat is to start off with a second-hand laptop with a broken screen. Remove all the unwanted stuff like the screen, keyboard and trackpad, then mount it somewhere under the chart table. Plug in a 12V screen, 12V power pack, keyboard and mouse.
 
nigelmercier said:
I have come to the conclusion that the best computer to have on a boat is to start off with a second-hand laptop with a broken screen. Remove all the unwanted stuff like the screen, keyboard and trackpad, then mount it somewhere under the chart table. Plug in a 12V screen, 12V power pack, keyboard and mouse.
Click to expand...
Lot to be said for that. a couple of come ports is really nice though, for getting ais & GPS in nice and stable or talking to a HF radio etc.
 
You must log in or register to reply here.

Other threads that may be of interest

PabloPicasso
Aboard connections
2 3
Replies
48
Views
977
PaulRainbow
PaulRainbow
PabloPicasso
Mains power
2 3
Replies
44
Views
981
PaulRainbow
PaulRainbow
MontyMariner
Battery failure
2
Replies
20
Views
815
Refueler
Refueler

Share this page

Top