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Re: [CQ-Contest] Field Day - Laptop Power Consumption

To: Bill Tippett <btippett@alum.mit.edu>
Subject: Re: [CQ-Contest] Field Day - Laptop Power Consumption
From: Zack Widup <w9sz@prairienet.org>
Date: Mon, 21 Jun 2004 08:27:22 -0500 (CDT)
List-post: <mailto:cq-contest@contesting.com>
My laptop runs off 24 volts DC.  I built an inverter using the Linear Tech 
LT1070 chip.  It generally draws between 0.5 and 1 amp at 24v (that's 1 to 
2 amps at 12v) when the disk drive is running but that power comsumption 
drops when the disk drive goes idle.

I've run it at least 12 hours from a small tractor battery with no 
problems.  

The neat thing about the LT1070 supply in "current-boosted boost mode" is 
that the input voltage can vary from anything between 5 and 50 volts and 
the output will stay rock-solid at 24 volts; the input current demand just 
changes in proportion to the input voltage.

73, Zack W9SZ


On Sun, 20 Jun 2004, Bill Tippett wrote:

>       Do any of you folks have experience running
> a laptop from battery power via an inverter?  I will be
> operating Field Day from a remote location and cannot
> use a generator.  I'll be using my K2 QRP with a fully-
> charged 75AH deep-cycle marine battery topped off by
> a 3W solar cell.  I'm planning to dedicate my RV's 84AH
> battery to the laptop via an inverter.  I'll put the laptop into
> maximum power-conservation mode but I cannot seem
> to find any specs on what its power consumption may be.
> The label on the laptop simply says "100-240V and 0.68-
> 0.37A" which I assume is at maximum power-consumption.
> This implies about 70 Watts and I'm wondering if I can make
> it through 24 hours even in max power-conservation mode.
> Has anyone been down this road before?
> 
>       If the 84AH battery dies, backup plans are:
> 
> 1.  Run the laptop for 3 hours from its internal battery.
> 2.  Switch to a second laptop for another 3 hours.
> 3.  Switch to the 75AH battery if there is enough power
> left for both the K2 and laptop.
> 4.  Switch to my truck battery...last resort since I also
> need to get home!  ;-)
> 5.  Pencil and paper (ugh!)
> 
>                               Help please!
> 
>                               Bill  W4ZV
> 

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