[Elecraft] Elecraft K3 drain at 5 watts CW only.

[Philip Townsend Lontz]

So, for Field Day running CW only any ideas about what the required amp hours will be?

Sent from my iPad

On Jun 15, 2013, at 8:06 AM, Michael Babineau <mbabineau at magma.ca> wrote:

> Robert : 
> 
> If you are planning to use Lead-Acid technology (SLA or wet-cell )
> then, as others have suggested, you should double your calculated capacity, as you never want
> to drain a Lead-Acid battery by more than 50% ..
> 
> so 
> 
> 10 hr requires 7 Ah
> 20 hr requires 15 Ah 
> etc.
> 
> The reality is that you will probably spend somewhat more than 50% of the time listening and tuning around
> for stations when you are S&P so the real split may be more like 30% TX and 70% RX, but 50/50 is probably
> a good guess. 
> 
> One further point .. don't discharge a Lead acid battery below 10.5 v. Repeatedly doing this will shorten
> its lifespan.  Don's suggestion of setting the low voltage indication on the K2 to 11v is a good idea.
> 
> For picnic-table-portable operations, battery booster packs (intended to jump-start cars) work very well
> and it is easy to find one with an SLA in the 10Ah to 20Ah range, often on sale. You can take the plastic
> case apart to install some fusing and even powerpole connectors to customize it for your application
> (I also removed the jumper cables from mine).  Some of these packs now even come with USB ports to allow for impromptu 
> powering/charging of i-Devices.  It is often cheaper to buy one of these than to purchase just the equivalent capacity SLA
> battery .. so you get a nice carrying case with a handle and other goodies for free. 
> 
> Best of luck ...
> 
> Michael VE3WMB 
> 
> 
> 
>> From: Robert G Strickland <rcrgs at verizon.net>
>> Date: June 14, 2013 6:28:10 PM EDT
>> To: Elecraft <elecraft at mailman.qth.net>
>> Subject: [Elecraft] K2 qrp battery drain estimation
> 
> 
>> If I'm operating a K2 at 5w cw, in S&P contest mode, I compute the current drain under the stated conditions as follows:
> 
>> conditions:
>> 50% listening, 50% transmitting
>> CW 50% duty cycle
> 
>> current:
>> 200ma receive, more or less
>> 1.0a transmit, more or less
> 
>> current draw per hour:
>> 100ma [30min rcv] + 250ma [30min xmit @ 50% duty cycle] = 350ma per hour
> 
>> 10Hr requires a 3.5Ahr battery
>> 20Hr requires a 7.5Ahr battery
>> etc...
> 
>> Is this more or less accurate, or have I missed something? Thanks.
> 
>> ...robert
> -- 
>> Robert G Strickland, PhD ABPH - KE2WY
>> rcrgs at verizon.net.usa
>> Syracuse, New York, USA
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