Powering laptop on board - best way

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Dave_Rolfe

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I want to use a laptop on board but do not know what is the best / most efficient way of doing so. I have heard that laptops are very power hungry so want to use whatever way is going to drain my limited batteries the least. I am on a swinging mooring so mains power is not available often.

Any advice of on the best way forward would be appreciated.
 
A laptop car adaptor is a fairly good way of powering it. Make sure you get one sufficiently powerful for your laptop - many laptops need a 120W adaptor. Maplin do one for about £30.
 
I use a decent quality built in inverter with enough power to run the laptop and more. This is wired to a socket near the chart table where I keep the laptop allowing me to leave it connected to the standard charger as though at home. I do take the batteries out once charged as this reduces the required power and prolongs the life of the laptop batteries.
When I some time ago measured the current the power supply was taking when powered through the inverter it was about 5A when charging the batteries and then fairly quickly dropping to about 1.5A when charged.
At the time of the test, I didn't know to take the batteries out so don't know what power is used in this state. My laptop runs as a chart plotter so is on pretty much all of the time the boat is moving. The inverter has worked for some 9 years without any problems and has outlasted the crappy old laptops I use.
I also use the inverter for low energy mains lights in the saloon as the light output is so much better than those originally fitted using similar amounts of energy.
Lots of people use 12v adaptors plugged into cigarette lighter style plugs but in my experience, they can get quite hot if used for a long time.

Cheers

Piddy
 
Use a 12v car adaptor from Maplins or the OEM supplier. DO NOT USE AN INVEROR as you waste a lot of the power in heat.

Have you already bought your laptop? If not then investigate it’s power rating. All laptops sold in the EU will have a power rating on them showing their nominal power consumption at their operating voltage.

Something like 19v = 4.32a
20v = 4.23a

This gives you an idea of the power drain. I would look for a laptop that runs off 12v (there are a few out there Levono and Dell have afew 12v models) so you don’t have to step up the voltage and use power heating things up.

Probably the biggest power user on the laptop is the screen and setting the screen and applications to use black backgrounds will reduce the AMPs consumes as will disabling any hardware component you don’t regularly use like network cards, Bluetooth, wi-fi, DVD/RW etc…..

/forums/images/graemlins/smirk.gif
 
It's not the powering system, it's the laptop and OS.

EG. PIII dual booting into Win 2000 = 6hrs, into LINUX 12 hrs.

That was an old Dell Inspiron 4000

Main reason for that is that Linux has a much better throttling system than WinXP.

The least power wastage you'll get is through a solid-state voltage varier.

Avoid Celeron chips, go for the slowest CPU, either Intel or AMD you can find with a small screen.
 
There's some very good advice here. Especially about processors, operating systems and applications. But on a more basic note re 12V Switch Mode adapters. (The 12V to 19V adapters). I have damaged two of these by having them plugged in when I started the engine. I've never looked at it but there must be a nasty spike that appears on starting and this has taken the PSU's out. Now it might be that these were a bit tender but they were 65 quid each at that time!! Never damaged an inverter though. Just worth bearing in mind.
 
The joke is - take out battery - wire direct to 12V. Or if you want to charge then you need the 16, 19, etc. volts the power brick says it delivers.
The only downside of no battery in - when computer needs "boost" to read CD / flash stick etc. it cannot draw on the battery to bolster. Some may argue about that - but I observed it with my IBM and Acer's ... my Inspectors also use Notebooks in car / travel and we found 12V convertors best - invertors are not used by us anymore since advent of reasonable cheap 12v convertors.
If you use a low wattage convertor - the battery boost I mention above shows itself well - after period notebook will show flat battery - due to draw on the battery when extra is needed. LED's usually flicker / light up indicating it also.
 
After working for two seasons with Toshiba satellite pro and a car-type battery charger (to get the 19 Volts from the 12 Volt boat supply) this summer I happily sailed and navigated with a tiny Asus 900 eeePC, directly fed via a cigarette lighter (I have one at the helm and a second one at the chart table)
To do serious work I connect it to the 20" LDCTV (also on 12 volts).
The Asus is slim enough to fit into the chart table, can work closed inside the table, with a wireless mouse and keyboard over the table: I consider muyself spoiled.
No ties with either Tosh or Asus, of course.
Cheers
 
[ QUOTE ]
.... there must be a nasty spike that appears on starting ....

[/ QUOTE ]

Get a good quality adaptor and make sure you have a ferrite on the input as well as the output. If you are generating that much of a spike when you start the engine you may have a problem with your alternator. You need to protect the circuit which a good 12v adaptor or inverter will do for you.

Taking 12v DC converting it to 240v or 110v AC and then back to 19V DC is IMO a poor way of getting power. Also apart from your screen most of the laptop components are using 6v, 3v or much much less. Just remember this rule of thumb:

Watts = Amps x Volts

I have 2 Maplin adaptors. One is connected at the chart table and the other is a spare or used when I move the laptop to the cabin table. I have had a 12v adaptor fail but then again I've seen many 240v/110v AC power supplied fail as well.
 
My adapter(s) were the proprietry ones that came with the Novatech laptop at the time.
There are in fact transient spikes produced when motors are engaged on the same circuit. Not the least of which is the starter motor. The alternator and associated were all fine.
Yes as I said the Novatech PSU might have been a bit "tender" but better safe than sorry for me since then!
I agree absolutely about introducing inefficiencies into the system, which is why I was using 12V adapters..
Thanks for the lesson on Ohm's law. Yes I have come across it before... In fact I'm old enough to have notated it as I=E/R /forums/images/graemlins/wink.gif

Cheers
Rob
 
Ohm's law (and all the other laws) aside I just hate using invertors but as you say sometimes needs must. I actually have one (an invertor) onboard that I use for Power tools but I've mamaged to convince SWMBO that her hair drier uses too much power (I hope she is not arond to read this!).............



/forums/images/graemlins/grin.gif I=E/R is better but just confuses a lot of people when you try and explain what is happening with AMPs on a boat. It is a black art afterall................................... /forums/images/graemlins/smirk.gif /forums/images/graemlins/laugh.gif
 
A vote for the Maplin car adaptor. The one I have (I suspect that being talked about) lets you change the polarity and voltage to suit your machine. Actually I'm so fond of them I have two for two different laptops (no single point of failure). If in doubt take the laptop with you to Maplins when you buy it.

Before adopting this strategy I used an inverter and found that it drew twice the DC power of the direct-to-DC solution (for one computer). The other one was more "interesting". It was a cheap, non-sine wave inverter I used. The computer went into a fit of high pitched rattling and I switched it off in alarm. My guess is that it thought its external power was being switched on and off in rapid succession - but someone might know better. No apparrent damage to the computer - but don't assume it'll work with any old inverter!
 
For my Thinkpad 600, I cracked open the Li-Ion battery and replaced the cells with 3 x Diodes in series, added a couple of ferrites and strapped a 12V Zener across the terminals. Then ran 3 wires out: one to the main battery, the second to a 12V gel-cell and the third (common) to both. No problems thus far.
 
Using PC's onboard - Electrical Supply

I use an IBM x200s running Sea Pro and Max Sea Navnet depending on the boat! Using an car adaptor I get good results.

Inverters can be affected by fluctuations on a boats electrical system causing instability on the pc which can manifest itself as blue screens.

The most important thing to be sure of is that the engine starting battery, under normal conditions, is separated from the domestic supply. In order to achieve this a split charging system must be installed. (Split charging Diode or a product such as Sterling's "0.0 Volt Drop Mutable Output Alternator Splitting Systems: ProSplit R")

Emergency starting is achieved by a cross over switch.

This also has the advantage of simplifying battery management and guards against complete discharge on alternator failure.
 
I mess about with PC s on board all the time and second what a previous chap mentioned. Dont use an inverter or transformer buy an eee pc which is the only one which runs on 12v (the only one I have found please let us know if others).

The ssd one draws 1.9 amps at 12v ( running xp, I have measured)

Next project is to try linux and see if it saves some power.
 
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