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Old 01-08-2011, 20:14   #1
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Laptop Power Consumption

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Clarity will be back in the water after a major refit, and I'm looking at electronic charting as a backup to paper. I'm on the learning curve re 12 volts. My laptop consumes 4.7 amps @ 19 volts, according to the AC adaptor. Does this mean that it will require 8 amps @ 12 volts before adaption? Seems a lot of energy compared with, say, a Raymarine 5 inch plotter's 8-10watts. Cheers. Bill
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Old 01-08-2011, 20:34   #2
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Re: Laptop Power Consumption

Maybe a little less but yes that's about right. Now I have not measured the power consumption of my laptop in steady use and doubt it pulls the max rating of the AC adapter but laptops do draw a pretty good bit of power.

If you really want to go low power draw you can assemble a PC and power supply that will draw a lot less that a laptop. There was a pretty good thread on this not long ago that you might find very interesting.

12vdc Marine Computers
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Old 01-08-2011, 21:04   #3
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Re: Laptop Power Consumption

Take a look at the recent "netbooks". These use a lower-power processor, and in general a slimmed down design, but usually have all the processing power you're likely to need. They're typically less expensive than a regular laptop, and draw perhaps 2A @ 12V.
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Old 01-08-2011, 21:07   #4
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Re: Laptop Power Consumption

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Take a look at the recent "netbooks". These use a lower-power processor, and in general a slimmed down design, but usually have all the processing power you're likely to need. They're typically less expensive than a regular laptop, and draw perhaps 2A @ 12V.

I've been looking at netbooks but would like to find one that runs on 12V without an adapter. So far the ones I've seen are all 19V. Know of any that are native 12V?
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Old 01-08-2011, 21:15   #5
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I've been looking at netbooks but would like to find one that runs on 12V without an adapter. So far the ones I've seen are all 19V. Know of any that are native 12V?
Probably pointless. Internally, new computers run on just a volt or two or three. So there are wasteful adaptors already inside. No getting around it. I'm not sure why 19V is so popular. Maybe it was a backlight or battery issue at one time. Or some other power hungry 19V component.
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Old 01-08-2011, 21:17   #6
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Re: Laptop Power Consumption

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Originally Posted by clarity36 View Post
...I'm looking at electronic charting as a backup to paper. I'm on the learning curve re 12 volts. My laptop consumes 4.7 amps @ 19 volts, according to the AC adapter. Does this mean that it will require 8 amps @ 12 volts before adaption? Seems a lot of energy compared with, say, a Raymarine 5 inch plotter's 8-10watts. Cheers. Bill
Hi Bill, If power is your major concern, you probably won't be able to beat a plotter with a laptop. But plotters require expensive chart chips. These may be OK if you're not going far, but it gets pretty expensive for us world cruisers. And you won't see much on your (relatively low resolution) 5" RayMarine screen.

We use OpenCPN with AIS so there can be a LOT of info to absorb in busy areas like the Malacca Straits (1,000 AIS contacts). I can absorb that much better with a big, high-resolution screen. I don't like looking at the world through a knot-hole.

Our Dell Vostro 1710 laptops draw 4-5A (@12v) when running normally. This is a price I'm willing to pay, but we don't leave the nav computer on all the time unless we're motoring (& our email computer is a low-power NetBook). On passage we don't really need it unless we see a ship who's relative bearing isn't changing. Then we can power it up, get the AIS info, & give them a call.

One thing that will help with power is to get a 12v computer power supply. These are usually much more efficient than trying to run your AC supply from a big inverter (& your big inverter actually doesn't like to power a computer switching supply). They usually cost ~$70, but make sure that it will both charge & run your computer. Dell laptops sometimes won't charge unless they're plugged into a Dell power supply, & our Dell supply is much more voltage sensitive than our 3rd party supply.

BTW, once you get it setup you'll probably find your paper is a backup to your electronic charts. Electronic charting is too magical. We carry paper for everywhere we go, but it seldom comes out of the locker.
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Old 01-08-2011, 21:18   #7
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Re: Laptop Power Consumption

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Probably pointless. Internally, new computers run on just a volt or two or three. So there are wasteful adaptors already inside. No getting around it. I'm not sure why 19V is so popular. Maybe it was a backlight or battery issue at one time. Or some other power hungry 19V component.
Exactly. When I got out of electronics chips were already running at 3V so it has to be the screen or something that likes the 19V.
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Old 01-08-2011, 22:44   #8
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Re: Laptop Power Consumption

So much quality, timely information. Thanks, fellahs. More food for thought, and 100% fat free
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Old 01-08-2011, 23:42   #9
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Re: Laptop Power Consumption

Laptops do vary (as does the efficiency of the 12v adapters), but the figures quoted by others seem a bit high. The laptop power supply often quotes the maximum current so is not a good guide. With a fully charged battery, full screen brightness and adaptive processor setting, operating from 12v my results are
T60P (15 inch screen) 3.1A
Notbook 1.1A
Using a DVD drive will add about 0.5A

LED lighting helps I can watch a movie on a 21 inch LED monitor played back via a netbook for 2.1A

These results are reasonably typical modern laptops tend to be better than the older versions. Screen size is a big factor.
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Old 02-08-2011, 02:55   #10
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Re: Laptop Power Consumption

I use a netbook running OpenCPN with AIS - far better display than a chartplotter - powered through a 12v to 19v converter from the chinese shop (15), it draws less than 20w and hibernates if not used for even lower power consumption.
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Old 02-08-2011, 03:06   #11
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Re: Laptop Power Consumption

I'm looking at an android tablet such as the Motorola Xoom.

It runs on 12 volts and Draws around 1amp, Ozi explorer runs on it and I'd be really surprised if an OpenCPN version is not too far away.

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Old 02-08-2011, 08:10   #12
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Re: Laptop Power Consumption

IIRC, the battery on my old laptop is putting out about 12v. I've been thinking about cracking one open, taking the internal batteries out, and hot-wiring it to the house bank. Maybe adding some capacitors in the empty space, to smooth out the house voltage.

That would be a very efficient way to go.

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Old 02-08-2011, 09:24   #13
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Re: Laptop Power Consumption

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Maybe adding some capacitors in the empty space, to smooth out the house voltage.
Not a bad idea...and maybe a series diode, resistor before the capacitance, or an inductor. It'll work better that way...no need try to filter the entire boat's electrical system.
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Old 02-08-2011, 15:48   #14
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Re: Laptop Power Consumption

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My laptop consumes 4.7 amps @ 19 volts, according to the AC adaptor. Bill
Bill, the information on your AC adapter is not the power consumption of the laptop. It is the maximum rated output for the adapter.

Typically the adapter will be rated at twice the actual consumption of your laptop.

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Old 03-08-2011, 01:12   #15
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Re: Laptop Power Consumption

Two things....

1) It's been a while since I've delved inside a PC, but the last I did the power requirement of the motherboard was 12V, +5v and -5v.

Also

My testing shows that my laptop, an acer aspire, draws approximately 4amps and charges the battery at approximately 4 amps both at 12v.

Cheers

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