12volt laptops

[merlin]

I am interested in using a laptop and navigation software to provide supplementary detail to my paper charts and pilot books. I already use an IBM Thinkpad but the battery life is not great. I don't really want to use an inverter since we usually sail rather than use the engine and even small inverters seem to create a large drain on the batteries.

Does anyone know of an efficient laptop that uses 12v or less and can be run effectively directly from the ships battery?

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[Happy1]

Go to Maplins, they have proper adapters for all/most laptops to fit a ciggie 12v lighter socket, about £20 or so.

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[robind]

Happy`s right, Maplins is the place. they also do a similar 12 volt adaptor that will increase the DC current up to as much as 20volts. it is set on a "graduated switch" on the side of the "transformer/inverter" piece of the gizmo, comes complete with all the plugs and fits most lap tops (not so if you listen to the manufacturers who want to sell you their own make) I run my Samsung off of mine. great piece of Kit.

Happy new year to you all

Rob

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[Talbot]

An alternative approach is to use one of the new generation small laptops such as the JVC or the Fujitsu p5000. They only have a 10" screen, but with the additional battery installed will provide in the region of 10 hours use.

Or you could go even smaller and use an Ipaq (or similar) some of the companies that make the software for laptops, also have a suitable product for the PDA.

Both of these approaches plus the use of the 12 volt adapter from maplins will extend your useable life whilst minimising the drain on the main battery.

Or you could buy a proper Chart Plotter, which is designed to minimise the current consumption.

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[mdrifter]

Why not use your Thinkpad directly from ship's 12V? Our Thinpad 390 has been doing Ok for 2 seasons this way using a Maplin sourced plug and wire for C£1.50; there is no need for an inverter; the Li-on battery can get close to 100% charge; to reduce consumption we remove the battery and the floppy/cd.

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[merlin]

Thanks for the reply. I also use the PC for weather via my SSB radio, Virtual Passage Planner etc etc so the chart plotter would just be more expense to provide a single function.




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[merlin]

Thanks for taking the time to reply. I have emailed Maplins about their product range but since they are inverter based I do not anticipate much luck.

I do not want to use an inverter based solution since they are so inefficient. As an example, from the outside of my PC power unit I read that the output is 3.36A at 16v. This is around 54 watts which at 12v would draw a current of about 4.5A. This is not too bad.

However, the input is 240v at 0.7A, which represents 170W. At 12v this would draw 14A. Inverters are only 80 - 90 percent efficient, this means that if I used an inverter to provide the 240v input then my poor old batteries would be sinking by 15.5 to 17.5 amps per hour to provide a mere 4.5A of benefit.

What I am really after is a solution that is either dc to dc and efficient, if such a thing exists, or maybe a 12v laptop. A new laptop would be cheaper than a chart plotter and provide a backup to the Thinkpad as well as more versatile (SSB link for weather, run other useful sailing software and prvide dvd player, cd r/w etc etc).

Happy New Year


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[merlin]

md drifter,

Thanks, I wondered about this but wasn't sure what would happen to the Thinkpad battery. It seems to work for you so I'll give it a go.

I'm currently cruising around Spain and want to visit the Balearics in the summer. The difference in detail between the chartlets in the Pilot book and the UKHO charts is considerable and I want to try to plug the gap to some extent with CMAP charts, hence the use of the PC for supplementary coastal navigation. I really want to keep the paper charts since I don't trust electronics on boats to the extent that I'd be dependent on them alone.

Happy New Year

Merlin

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[claudio]

Merlin,

You're calculations don't stack up

If you're saying that the laptop draws 54 Watts at 12V and the brick is around 80% efficient, it cannot possibly draw 0.7A at 240V.

If it does, what consumes the extra power ?

The laptop will probably draw 54 Watts with a flat laptop battery, the CD/DVD running and intensive processing.

With a fully charged laptop battery, I would think that the laptop draws no more than around 3A at 12V.



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[daveking]

If you are not too concerned about speed etc, try and get your hands on an old Toshiba I have a 200CDT , which has a P100 chip 24 MB ram and a 2.1 gig HDD it cost me 100 quid and is 12 volt. the battery is dead but I can connect to the battery terminals and straight to the boat supply, or at home plug up to the 240 supply. I run Seaclear for navigating this links to a garmin gps and wheel pilot 5000 ,and the low spec of this machine is more than adequate. I have a 2.4gig P4 laptop but as it cost me nearly 2k, water and electronics don't mix so 100 quid, 12 volts, and low power consumtion sound good to me
regards Dave

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[MainlySteam]

As Robind and Happy1 say, the best solution for most is one of the dc-dc step up supplies that does 12 volts to a range of selectable voltages (frequently as high as 24v) - most modern laptops seem to be around 18v for full battery charging.

A concern I had using them was that when charging the boat's own batteries and the service voltage got up to over 14v at the last charging step, whether the dc-dc convertor for the laptop would hold its voltage and not overcharge the laptop's battery. I use a Vanson SDR-70W which was cheap (I know Vanson is available in the UK) and have found that its voltage output is dead stable even when the boats 12 v supply climbs up over 14 volts.

You say you use the computer for weather fax - you may find that some dc-dc convertors are noisy in the radio's receiver which may in turn put some hash over the received fax. If so the solution is to use a clip on block ferrite with about 4 turns of the convertor's cable wound through it (usually the convertor's output cable is the main problem, and is also usually the only one long enough to wind on a ferrite).

John

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[merlin]

Hi Claudio,

My point exactly - where does the power go. As regards the figures, they come straight off the IBM power unit. If you have similar why not check your own and you'll probably find a similar discrepancy.

The formula for power consumption is straightforward, power=volts X amps

240 * 0.7 = approx 170
170 / 12 = 14

If I then use an inverter which is about 80 percent efficient to provide the 240v it costs the battery

14/.8 = 17.5

Thanks,

Merlin

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[merlin]

Thanks John,

This sounds like just the job, I'll scout around for one.

Merlin

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[davidbains]

DC/DC converters work fine, either a cheapie from Maplins or a branded car lead
from the laptop manufacturer. I know of skippers who connect older Toshibas requiring 15 volts straight to the battery with good results. The thing is not to get a laptop that needs mains for it's own internal inverter. The external DC/AC inverters are noisy and radio interfering with their fans and get hot so must be inneficient.
OR use an Mac Ibook or Powerbook which require 24volts, either from a Mac car lead, or even from ship's 24 volt supply if available. I recommend secondhand Ibook from Shaye. They are student proof and have very long life batteries. You can still buy an older Mac version of Maxsea which will run well with Mapmedia charts. Or add Virtual PC and run anything you like. Download Multimode from Black Cat systems for WFax and radio decoding.

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[pandroid]

Dont wory about it. I've actually measured the current drawn using a Targa DC-DC converter (which I use on my boat) into both Toshiba and Compaq laptops. A fully charged laptop draws around 1.2 amps, rising to about 3 amps on charging (measured from the 12v input to the Targa). This is no more than the Raymarine Radar/plotter (which, after all, is only a computer in a box!) The numbers quoted on the PSUs are usually peak values of what the unit is capable of. No laptop is going to draw 4 amps - the batteries would be huge!

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[Mariner]

You have a couple of options. If you are concerned about power usage, do not buy a Maplins cheapie twenty quid inverter. A true sinewave inverter is very efficient and allows your power supply to run cooler although they cost quite a bit more than twenty quid, in fact you could pay ten times that for a quality one.
You could also use as people have mentioned a dc-dc conerter. We can suply a dc-dc power supply suitable for the majority of laptops on the market as well as a 240/dc-dc converter. If you need more info drop us a mail.
Martin

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[sailorgirl]

We use 'Juice' - its a relatively new pack of connectors for auto, plane & boat use. Simply choose the right combo and you can run your laptop, PDA or phone from any 12V supply. I think our mobile phone connectors were an extra accessory but anyway its available in places like airport Dixons.

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[mjth8]

Re the suggestion to go to Maplins, it's a good idea. Ask them for a Vanson SDR-70W. This is a DC to DC converterThere are various models available the one that I use is switchable from 15 to 24 volts DC. Cost about £20.00.
Mike Arold

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