[Elecraft] Battery requirements for NPOTA activation with KX3/KXPA100

[Nels Anderson]

Having recently done several NPOTA activations I'll share my experience. 
I have a non-Elecraft radio permanently mounted in my truck (my nice K3 
station stays home), run about 100 watts into a typical screwdriver 
antenna. I ran off the single battery in my truck, which is good for 
about 50 to 60 amp hours (non-AGM battery).

In past years I've done contests where I hunt and pounce and have gone 4 
or more hours without killing the battery. NPOTA is way different! The 
last time I went out, not thinking about the duty cycle difference, I 
operated about 2 to 2.5 hours and when I went to start the truck the 
battery was dead. In that time I'd made 176 QSOs, so don't think that 60 
QSOs per hour is optimistic...it's easily accomplished if conditions are 
good. And that means you'll be transmitting a lot.

So, I killed a car battery in 2 or so hours. If you want to operate 6 
hours you're going to need roughly the equivalent of 3 standard car 
batteries. Not very scientific I know, but a reasonable estimate I think.

I'm now looking to install a second battery in the truck, as I want to 
do more NPOTA activations...

73 Nels K1UR


On 3/29/2016 4:41 PM, Esquer Dave wrote:
> Hi folks,
> I know this has been asked and discussed before but I can’t seem to get a handle on a clear-cut answer …
>
> I am going to do a SSB NPOTA (National Parks on the Air) activation with my KX3/KXPA100/PX3 on battery power. It has been in the works for a while with a special use permit required by the NPS.
>
> How much battery capacity do I need if I want to run full 100 watts? For planning purposes, I am assuming a 6 hour activation with a (highly optimistic I know) 60 QSOs per hour.
>
> The PX3 will be powered by a separate LiFePo 4.8 aH battery, it will do just fine. My concern is the amount of draw I will need to last the 6 hours. With an inline (Hobby King) HK-010 Power Analyzer, I see a max current (KX3/KXPA100 combo) of about 8 amps and about 80 watts during a QSO. The QSOs varies between 50-80 watts on transmit.
>
> I also know that once I am spotted, I can drop the power down to maybe 75-50 watts to save some battery juice.
>
> I have 2 12v-18aH SLA batteries at the ready, am I woefully underpowered? If you have any real-world experience or tips, it is most valuable and appreciated. You can contact me offline at dave dot esquer AT gmail as well.
>
> Thanks,
> Dave, K6WDE
>
>
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to nels at flightsim.com