View Full Version : Satelite up/down link

10-12-03, 16:36
We are soon moving aboard and we want to have a laptop to upload/download on the internet. We are thinking of power from wind/solar then to a storage battery then to a converter. Does such a system take a lot of power? Space is at a premium.

<hr width=100% size=1>

10-12-03, 21:37
recommendation that I have had is not to go through an inverter, but to use a step up device (like dell use) it will use less power

<hr width=100% size=1>

11-12-03, 08:43
The amount of power a laptop uses depends on its make and what its doing. In measurements I've made, using a dedicated power pack (i.e. Targa adaptor) the range varies from about 0.8 amp (on but fully charged), to 3amps (on, charging). This is broadly comparable with a small boat radar. The targa adaptor is not cheap (75) but is about the size of a packet of fags. Depending on how much you intend to use this thing, you can power it off the normal boat batteries.

I'm not sure of what any sattelite system will take but it shouldnt be much.

<hr width=100% size=1>

11-12-03, 13:21
We've been supplying systems to run this type of thing for about 7 years now.

Your notebook will pull about 90W when running (7.5A). Therefore, running it continuously is not probably viable. Supposing that you ran it four 4 hours a day it will pull about 30AH. This means your solar/wind system will have to generate 30AH of charging - minimum per day.

Bear in mind that a solar panel will only produce it's rated output in optimum conditions (eg on the equator, being kept cool and at midday). Therefore, it's safer to divide the rating by 2 to give an idea of real power output. A 100W panel would produce average of 50W = 4.16A - meaning that you would need 7.2 Hours of sunlight to replace the 30AH. You should adjust these figures by 10% to allow for ineffeciencies within the system.

A smaller wind turbine (like the Rutland 503) would probably produce more power as it has the opportunity work for 24 Hours - providing the wind was there.

On the subject of inverters to run notebooks, we need to dispell some myths...

Firstly, Compaq have designed an inverter, built under license specifically for running notebooks in mobile applications. I sell this to Toshiba, Canon, TI etc. ALL of these manufacturers also provide the DC/DC step down convertors (cig lighter leads) for running in cars. However, they don't recommend using them on boats - the main reasons being:

The voltage input range of a converter is 12-14VDC. Boat systems have a normal range of 10-14.8V - with smarter charging systems installed. Result - converter isn't able to regulate it's output properly.

Boat electrical systems are subject to substantially more voltage spikes and RFI noise than those on cars - again something the converter won't be able to necessarily filter out.

For these two reasons, notebook manufacturers suggest using an inverter (that is built to withstand these fluctuations) to run the PC's normal power supply (that also incorporates spike protection.

Note also that a dc/dc adaptor provides power to the motherboard - any spikes could blow components on that board. Because you weren't using the proper power supply "brick" your warranty may be invalidated.

Running through an inverter isn't going to be too power hungry - as long as you opt for one of reasonable quality. The unit designed by compact adds about 5% to the DC power draw - so that 4.16A would grow to 4.368A. A small price to pay for properly protecting your computer.

Also, if any inverter "expert" tells you that you must have a pure sinewave unit to run your notebook (or desktop for that matter) - he really doesn't know what he's talking about. ANY computer will safely except a well regulated Modified Sinewave.

Take a look at my site www.merlinequipment.com for more info.

Hope this helps!

Regards - James

<hr width=100% size=1>

12-12-03, 14:50
Thanks for your information James.
I'll visit yout site and be in touch.

<hr width=100% size=1>