Computers

[BillG]

I plan to make more use of our computer this year, including using it for naviagation.  The batteries only seem to last about two hours and I have a question about recharging them.  I have a  small 700 watt inverter located near the nav station.  Is it ok to plug the regular AC charger into the inverter or is it better to buy a dedicated DC charger  thats designed to plug into an Aux plug, or does it not matter.

[Stu Jackson]

Either way will work.  There are some inefficiencies in converting Dc to AC in the inverter.  And the computer itself is DC anyway.  But for the relatively low load,  and the reasonably short amount fo time you'll be using it, it doesn't matter.

[rirvine]

Stu is correct a DC-to-DC power source is the right solution.  I found the best solution was to use a power adaptor made for use in an automobile – usually plug into the cigarette lighter.  Because the connector had a tendency to fall out of the lighter socket on my boat, I hard wired the DC-to-DC converter in so the only connector in the circuit was from the converter into the computer.   The set-up has worked AOK for some 24 months.  I use a MAC laptop (required 18VDC input) running the MacENC package.

BTW:  Before going to far down the DC-DC converter road, one need to know what voltage the computer expects from the converter - not all use 12VDC.  If you are lucky enough to have one that uses 12DC, then you need is a voltage regulator if you are concerned about input voltage changes.

Have a computer connected into the boat instruments is a great toy – enjoy it.  You can see some of my screen shots on: http://www.flickr.com/photos/crews_nest/

Ray

[Rick Johnson]

The problem is the condition of the power being supplied to the computer.  Our boat systems are not designed to provide smooth (no spikes or drops) power to a computer and you can easily pass a killing spike through an inverter or a laptop power supply.  If you go the dc/ac route make sure you add a good quality surge protector between the inverter and the laptop power supply.  The other way is to go with a power supply designed to provide conditioned power to a computer in a car.  This would not be the ones that plug into the cigarette lighter, but are designed for hardwired computer/monitor installations in custom cars.  These are also not designed for the marine environment but should last a reasonable amount of time if you can install it in a clean, dry location.  The manufacture I'm most familiar with is http://www.carnetix.com/index.html.

Cheers,

Rick

[Ron Hill]

Bill : Wrote this up in the Mainsheet a few years ago. 
You need to get a 12v air/auto charger that will charge at a lower voltage.  I have a Dell and talked to  the CHARGER manufacturer and they exchanged my 12/14v charger for a 10/12v charger.  Give it a try!! 

[David Sanner]

Rick, that carnetix looks like a very nice DC-DC adapter (around $100).
It can even work in starting situations of only 7 volts input.

I would definitely recommend going with a DC to DC adapter as they
are probably close to twice as efficient as DC -> AC -> DC.

I have an old IBM thinkpad and use their universal travel adapter
to go DC -> DC.  I also have a remote LCD screen that I've just
directly wired into the house bank (though I should probably put a
voltage regulator in there to minimize the peaks/noise when
charging with the alternator).

[Ted Pounds]

Here's a copy of a WSJ article on this subject.  I had to get rid of the picture in order to meet the 75KB size limit for attachments.

[Stu Jackson]

Photo postings:  see  http://c34.org/bbs/index.php?topic=3701.0