[Elecraft] OT - Solar panel output

[WILLIS COOKE]

Don, I think we are pretty much in agreement.  I
originally stated that a 33 watt charger was about
right for a K2 and someone replied that it was way
overkill.  In practice, it takes a really good set of
operators to transmit 25% of the time and few field
day crews will do that.  You experience with a 35 amp
battery would tell me that things were just about in
the right balance.  

Willis "Cookie" Cooke, K5EWJ, PE

--- dolfindon at msn.com wrote:

> Hi
>  
> Actually 33 watts is more than enough to power a QRP
> K2. You only transmit about 25 % of the time and
> receive the rest so running a K2 at 10 watts will
> only require about 15 watts to keep the battery
> charged. For a 100 watt K2 you will need about 75
> watts of panels and about a 35 amp hour battery to
> run continuously. I know this works because this is
> the setup one of the operators used on field day
> here in Tyler Texas a couple of years ago. The panel
> was set up out in a field about 100 ft away from the
> rig. The controller was one of my Solar Controller
> Kits and the battery was a 35 amp hour gel cell like
> used on electric wheel chairs. We operated night and
> day CW at 75 watts out. The battery kept us running
> all night and the solar panel had the battery back
> fully recharged by mid day.
>  
>  
> Don Brown
> KD5NDB  
> 
> 
> 
> > Date: Wed, 19 Mar 2008 10:34:21 -0700> From:
> wrcooke at flash.net> Subject: Re: [Elecraft] OT -
> Solar panel output> To: k0pp at rfwave.net;
> alsopb at nc.rr.com; Elecraft at mailman.qth.net> CC: > >
> > --- Ken Kopp <k0pp at rfwave.net> wrote:> > > We have
> an RV with 12A of solar panels on the roof.> > They
> charge a bank of 4 golf cart batteries with a> >
> total> > capacity of 440 AH> > > > It's surprising
> the amount of energy they will> > deliver,> > even
> on a rainy day. Nothing near the 12A, but> > still>
> > several amps.> > > > We have the experience to
> back this up ... 5 years> > of six (winter) months
> each on the Oregon coast.> > (:-))> > > > Didn't
> want the idea that solar panels are useless> > in> >
> the rain or a on a cloudy day to get started.> > > >
> 73! Ken Kopp - K0PP> > ElecraftCovers at rfwave.net> 12
> AMPS of solar cells is a lot bigger than the 33>
> watt unit that we were discussing. 12 amps X 14
> volts> is 168 watts. The 33 watt unit is less than
> 2.5 amps,> barely enough to run a transceiver
> continuously during> good sunlight.> > > Willis
> 'Cookie' Cooke > K5EWJ>
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Willis 'Cookie' Cooke 
K5EWJ