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Solar power for the K2

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Kenneth Christiansen

Solar power for the K2

I got into some wrong notes this morning. 600 MA is the amount adding
the KPA-100 adds to the K3 during key down or transmit conditions. My
earlier measurements were the right ones. I have the larger solar
controller from Don Brown KD5NDB and it works well with an AC power
supply I use to keep my battery charged. I have been using this for 6
years and now wonder if any advances have been made in solar cells so a
ham can use them. I looked up a 70 watt solar panel on the internet and
it was $500. I can't justify that and don't have any idea if it is even
small enough to take car camping. Does anyone have any suggestions for
solar power or do I just need to buy a second large battery?
Thanks and 73

Ken W0CZ
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Andrew Moore-3

Re: Solar power for the K2

I'm very interested in hearing responses to solar setups for use with
the K2 and would appreciate seeing replies shared on the list, if it's
not considered too off-topic.

Thanks,
--Andrew

On Tue, Mar 18, 2008 at 3:32 PM, Kenneth A. Christiansen <[hidden email]> wrote:

> I got into some wrong notes this morning. 600 MA is the amount adding
> the KPA-100 adds to the K3 during key down or transmit conditions. My
> earlier measurements were the right ones. I have the larger solar
> controller from Don Brown KD5NDB and it works well with an AC power
> supply I use to keep my battery charged. I have been using this for 6
> years and now wonder if any advances have been made in solar cells so a
> ham can use them. I looked up a 70 watt solar panel on the internet and
> it was $500. I can't justify that and don't have any idea if it is even
> small enough to take car camping. Does anyone have any suggestions for
> solar power or do I just need to buy a second large battery?
> Thanks and 73
>
> Ken W0CZ
> _______________________________________________
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n6wg

Re: Solar power for the K2

In reply to this post by Kenneth Christiansen

Ken
Look up Northern Tools.

I've bought several 15w solar panels from them,
all under $90. Some I even got during a
promotion where they paid shipping :-)

73, Bob N6WG

----- Original Message -----
From: "Kenneth A. Christiansen" <[hidden email]>
To: <[hidden email]>
Sent: Tuesday, March 18, 2008 11:32 AM
Subject: [Elecraft] Solar power for the K2

> I got into some wrong notes this morning. 600 MA is the amount
adding
> the KPA-100 adds to the K3 during key down or transmit conditions.
My
> earlier measurements were the right ones. I have the larger solar
> controller from Don Brown KD5NDB and it works well with an AC power
> supply I use to keep my battery charged. I have been using this for
6
> years and now wonder if any advances have been made in solar cells
so a
> ham can use them. I looked up a 70 watt solar panel on the internet
and
> it was $500. I can't justify that and don't have any idea if it is
even
> small enough to take car camping. Does anyone have any suggestions
for

> solar power or do I just need to buy a second large battery?
> Thanks and 73
>
> Ken W0CZ
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
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WILLIS COOKE

Re: Solar power for the K2

In reply to this post by Kenneth Christiansen

Ken, I show a 33 watt solar charger in Northern Tools
that is $299.99 and 38"X11-3/4"x1" and 13 lbs. Doable
in a car, but a bit big for back packing. Also
pricey. It does not include a controller at that
price.

--- "Kenneth A. Christiansen" <[hidden email]> wrote:

> I got into some wrong notes this morning. 600 MA is
> the amount adding
> the KPA-100 adds to the K3 during key down or
> transmit conditions. My
> earlier measurements were the right ones. I have the
> larger solar
> controller from Don Brown KD5NDB and it works well
> with an AC power
> supply I use to keep my battery charged. I have been
> using this for 6
> years and now wonder if any advances have been made
> in solar cells so a
> ham can use them. I looked up a 70 watt solar panel
> on the internet and
> it was $500. I can't justify that and don't have any
> idea if it is even
> small enough to take car camping. Does anyone have
> any suggestions for
> solar power or do I just need to buy a second large
> battery?
> Thanks and 73
>
> Ken W0CZ
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
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>
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> Elecraft web page: http://www.elecraft.com
>

Willis 'Cookie' Cooke
K5EWJ
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k7nhb

Re: Solar power for the K2

In reply to this post by Kenneth Christiansen

Andrew,
When reading the other posts and seeing those large Solar Panel
wattages, I think they are using a K2 but with the 100W option. I
can't imagine needing a 33W solar panel to power the base K2 model.
On a nice day, I guessing you could hook up a 7 Ahr gel cell and have
it charged with a 5-10 Watt panel and work for a long time. The
battery supplies the TX power when you need it and during the RX
cycle the Solar Panel is catching it for power used.

You might try posting your question on the Yahoo QRPSolarPower newsgroup.
73,
Paul
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John Lonigro

Re: Solar power for the K2

Andrew:
This is exactly what we do at Field Day every year. We "search and
pounce", so our transmit duty cycle is relatively low, but after
operating all afternoon, the 7 Ahr battery used with the QRP K2 is
almost fully charged (assuming sunny weather, of course). We use two 5
Watt solar panels in parallel, each costing less than $40, hooked up to
an inexpensive gelcell charger, to keep the battery from overcharging
(probably not necessary with these solar panels).

73's,
John AA0VE

Paul wrote:

> Andrew,
> When reading the other posts and seeing those large Solar Panel
> wattages, I think they are using a K2 but with the 100W option. I
> can't imagine needing a 33W solar panel to power the base K2 model. On
> a nice day, I guessing you could hook up a 7 Ahr gel cell and have it
> charged with a 5-10 Watt panel and work for a long time. The battery
> supplies the TX power when you need it and during the RX cycle the
> Solar Panel is catching it for power used.
>
> You might try posting your question on the Yahoo QRPSolarPower newsgroup.
> 73,
> Paul
>

alsopb

Re: Solar power for the K2

It seems like it would be cheaper and easier to do away with the solar
panels and charger. Use the money to buy a few more batteries. Charge
them before FD and you're good to go.

Think about this. It may even rain on FD! The solar panels would only
be good as an ad hoc umbrella or tent during the rain.

73 de Brian/K3KO

John R. Lonigro wrote:

> Andrew:
> This is exactly what we do at Field Day every year. We "search and
> pounce", so our transmit duty cycle is relatively low, but after
> operating all afternoon, the 7 Ahr battery used with the QRP K2 is
> almost fully charged (assuming sunny weather, of course). We use two
> 5 Watt solar panels in parallel, each costing less than $40, hooked up
> to an inexpensive gelcell charger, to keep the battery from
> overcharging (probably not necessary with these solar panels).
>
> 73's,
> John AA0VE
>
> Paul wrote:
>
>> Andrew,
>> When reading the other posts and seeing those large Solar Panel
>> wattages, I think they are using a K2 but with the 100W option. I
>> can't imagine needing a 33W solar panel to power the base K2 model.
>> On a nice day, I guessing you could hook up a 7 Ahr gel cell and have
>> it charged with a 5-10 Watt panel and work for a long time. The
>> battery supplies the TX power when you need it and during the RX
>> cycle the Solar Panel is catching it for power used.
>>
>> You might try posting your question on the Yahoo QRPSolarPower
>> newsgroup.
>> 73,
>> Paul
>>
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Ken Kopp-3

OT - Solar panel output

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
[hidden email]

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WILLIS COOKE

Re: OT - Solar panel output

--- Ken Kopp <[hidden email]> 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
> [hidden email]

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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Don Brown-4

RE: OT - Solar panel output

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: [hidden email]> Subject: Re: [Elecraft] OT - Solar panel output> To: [hidden email]; [hidden email]; [hidden email]> CC: > > > --- Ken Kopp <[hidden email]> 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> > [hidden email]> 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> _______________________________________________> Elecraft mailing list> Post to: [hidden email]> You must be a subscriber to post to the list.> Subscriber Info (Addr. Change, sub, unsub etc.):> http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm> Elecraft web page: http://www.elecraft.com_______________________________________________
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WILLIS COOKE

RE: OT - Solar panel output

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

--- [hidden email] 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:
> [hidden email]> Subject: Re: [Elecraft] OT -
> Solar panel output> To: [hidden email];
> [hidden email]; [hidden email]> CC: > >
> > --- Ken Kopp <[hidden email]> 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> > [hidden email]> 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>
> _______________________________________________>
> Elecraft mailing list> Post to:
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> sub, unsub etc.):>
> http://mailman.qth.net/mailman/listinfo/elecraft > >
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k6dgw

Re: RE: OT - Solar panel output

In reply to this post by Don Brown-4

[hidden email] 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.
>

My experience [not nearly as much as N0SS and others] is that a good
half or more of the challenges to the use of solar power is in the
"usage" rather than the "generation" side of the equation.

Many years ago and when solar cell efficiencies were much lower than
today, my engineering team and I got the job of designing a UHF multiple
repeater communications system for a petroleum pipeline operation in So.
Africa. We started the design with the normal equipment at the sites
that we had always used, and a humongous solar array good for about 400A
in full sun with a bank of glass jar batteries for a 48V primary
circuit. Based on historic solar irradiation data, the 24/7 power
budget was pretty much balanced with a 40% safety pad, which was close
to but not quite 3-sigma.

400A under full sun resulted in some fairly expensive structural
construction, wiring, control, and batteries, none of which really
impressed our customer. Thus encouraged, we undertook to trim the
usage, which turned out to be the really fun part of the engineering.
We got each site down to an eighty amp array with sealed, much cheaper
but far more long-lived batteries for the same "almost 3-sigma power
budget pad." In reality, that still turned out to be overkill after it
had gone into operation.

I charged my 12V 12Ah gel cell with a 1A RV solar array/controller and
ran my K2 at 15W for 4 hours for the 2007 Flight of the Bumblebees. I
called CQ a lot. The terminal voltage of the battery never varied, and
I've used it since without recharging. Every watt-hour if drain you
save in drain is a smaller capital investment in charging equipment. My
K2 was a good conserver, I'd bet a K1 would be better, and my KX1 could
make my solar-charged batter last longer than my lifetime :-)

As many of you Elecrafters as can should get into the FOBB. It's in the
middle of the summer [in the N. Hemisphere], it's fun, and you'll make a
lot of Vitamin D while you're knocking off Q's if you do it in the
field. Vitamin D is good for you :-)

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2008 Cal QSO Party 4-5 Oct 08
- www.cqp.org
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John Lonigro

Re: Solar power for the K2

In reply to this post by alsopb

Brian:
We have plenty of gel cells for Field Day, and, as you noted, don't
really need to use the solar panels at all. However, we get 100 bonus
points when we make QSOs using a battery charged via solar energy. You
can't forget bonus points!
73's,
John AA0VE

Brian Alsop wrote:

> It seems like it would be cheaper and easier to do away with the solar
> panels and charger. Use the money to buy a few more batteries. Charge
> them before FD and you're good to go.
>
> Think about this. It may even rain on FD! The solar panels would
> only be good as an ad hoc umbrella or tent during the rain.
>
> 73 de Brian/K3KO
>
> John R. Lonigro wrote:
>
>> Andrew:
>> This is exactly what we do at Field Day every year. We "search and
>> pounce", so our transmit duty cycle is relatively low, but after
>> operating all afternoon, the 7 Ahr battery used with the QRP K2 is
>> almost fully charged (assuming sunny weather, of course). We use two
>> 5 Watt solar panels in parallel, each costing less than $40, hooked
>> up to an inexpensive gelcell charger, to keep the battery from
>> overcharging (probably not necessary with these solar panels).
>>
>> 73's,
>> John AA0VE
>>
>> Paul wrote:
>>
>>> Andrew,
>>> When reading the other posts and seeing those large Solar Panel
>>> wattages, I think they are using a K2 but with the 100W option. I
>>> can't imagine needing a 33W solar panel to power the base K2 model.
>>> On a nice day, I guessing you could hook up a 7 Ahr gel cell and
>>> have it charged with a 5-10 Watt panel and work for a long time. The
>>> battery supplies the TX power when you need it and during the RX
>>> cycle the Solar Panel is catching it for power used.
>>>
>>> You might try posting your question on the Yahoo QRPSolarPower
>>> newsgroup.
>>> 73,
>>> Paul
>>>
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>>
>
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