Using the KX1 on Solar Power

[Michael Heit]

Has anyone used the KX1 in the field with solar power ? If so, was any info
sent on this list?
I am building a KX1 and was interested in using solar , or solar back up
power for extended field use.
Thank you very much.

Michael Heit KD7YLA

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[Don Brown-4]

Hi

I have not done this with a KX1 but it should be easy. An 8 or 10 cell set
of NiMH batteries would work on a small solar panel. You would need to size
the panel to fit the approximate 1/10C charge rate for the cells and connect
the panel through a blocking diode directly to the battery. You would then
connect another set of wires to the battery to power the KX1. A set of
1800-2500 mA Hr batteries would work with a 3 to 5 watt panel. The
Volkswagen panels that show up on EBay at about 170 mA would work without
needing a charge controller. NiMH batteries can be charged at 1/10C almost
indefinitely without damage.  If you are going to use a SLA battery then you
will need a controller or you will need to monitor the voltage carefully so
you do not overcharge the battery. You can use one of my charge controller
kits with a small 2-3 amp Sealed lead acid battery. The controller kit is
$30 check or money order from.

Don Brown
19132 Falls Creek Drive
Flint Texas 75762

Thanks

Don


----- Original Message -----
From: "Michael & Donna Heit" <[hidden email]>
To: <[hidden email]>
Sent: Tuesday, June 21, 2005 2:24 PM
Subject: [Elecraft] Using the KX1 on Solar Power

> Has anyone used the KX1 in the field with solar power ? If so, was any
> info
> sent on this list?
> I am building a KX1 and was interested in using solar , or solar back up
> power for extended field use.
> Thank you very much.
>
> Michael Heit KD7YLA
>
> _______________________________________________
> 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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[Scott-204]

Don Brown mentioned the VW solar panels...

After seeing them referenced on this list a few times over the years, I
finally went to the local dealer yesterday, asked gently about solar panels,
and walked away with two of them. What a deal!

( Now I'm wondering: Why does one read 15V and the other 25V when they're
side by side? )

Scott N1AIA
K1 00139

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[Bruce Grubbs]

I've used a 1.4 watt panel with a ten NiMH AA cell pack with the K1 with great
success. On the other hand, with the KX1 on a backpack trip of a week or more
where weight is critcal, I run it on a set of AA lithium throwaways, and
carry a spare set. Both sets together weigh the same as a single set of NiMH,
and will run the rig for several weeks- in fact I've never run the first set
down on a trip. And I don't need to carry a solar panel.

For a non-wilderness situation, car camping or the like, I use the above NiMH
pack and solar panel to save the expense of the lithium cells.

72,
Bruce
N7CEE
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[Don Brown-4]

Hi

There may be two different types out there or you may not have them in the
same intensity light. A Solar panel is a constant current generator. Its
current and open circuit voltage is dependent on the amount of light falling
on the panel. Each cell in the panel outputs about .5 volt in full sun. The
cells are connected in series or series-parallel to get the voltage high
enough to charge the battery plus a little overhead. The VW panels only need
about 14 volts to charge the battery in the car so they may have a version
of the panel wired for only 15 volts. The three panels I once had would
output about 18 volts in full sun open circuit and about 170 mA under full
load. You can test the output current by connecting a 10 ohm 5 watt resistor
across the panel and measuring the output voltage. 170 mA would be 1.7
volts. I have some commercial Solarex panels that will output up to 30 volts
open circuit in full sun and almost 6 amps under load. This panel is about
20x57 and rated at 80 watts. The VW panels have a blocking diode in the plug
to prevent reverse current. This reverse current will discharge the battery
when the panel is dark. If you remove the plug be sure to install a blocking
diode unless your controller includes one internally. You can parallel
several panels to increase the current but a blocking diode is a good idea
on each panel to prevent reverse current flow when one panel is in the sun
and another is in the shade. Even if you have two panels with different
voltages if you parallel them through the blocking diodes once they are
connected to a load the voltage will drop to the battery voltage and the
current from each panel should flow into the battery.

Don Brown

KD5NDB



----- Original Message -----
From: "Scott" <[hidden email]>
To: <[hidden email]>
Sent: Tuesday, June 21, 2005 6:48 PM
Subject: Re: [Elecraft] Using the KX1 on Solar Power

> Don Brown mentioned the VW solar panels...
>
> After seeing them referenced on this list a few times over the years, I
> finally went to the local dealer yesterday, asked gently about solar
> panels,
> and walked away with two of them. What a deal!
>
> ( Now I'm wondering: Why does one read 15V and the other 25V when they're
> side by side? )
>
> Scott N1AIA
> K1 00139
>
> _______________________________________________
> 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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[G3VVT]

 
In a message dated 22/06/05 15:26:09 GMT Daylight Time, [hidden email]  
writes:

You can  test the output current by connecting a 10 ohm 5 watt resistor
across the  panel and measuring the output voltage


Reply: .....................................................
 
In practice you do not even need to do that.
 
During some commissioning of a large solar powered microwave system I was  
involved with about 5 years back that used up to 15kW of solar power  at each
site (200 x 75W 12V solar panels), the contractors who installed the  system
tested the output by connecting an ammeter effectively directly across  the solar
panel output terminals. When I raised the question would this not  cause
damage? They came back quite rightly, no, the current will limit at what  the
solar panels are capable of providing. In these installations  the total array was
divided into 12 banks of 48V sections with panels in series  and parallel to
make up the arrangement. As the current involved was  considerable the method
involved was to place a heavy gauge piece of wire after  the solar panel
breaker and when the bank was activated measure the  resulting current through the
piece of wire with a calibrated AC/DC clamp type  current sensor and a DVM.
 
With the type of solar panels normally used by hams, probably a  DVM on a
suitable current range direct across the solar panel terminals would do  the job.
You have to take care that the panel being tested is isolated from all  other
power sources such as batteries, but at the end of the day the panel will  
not supply any more than what it is rated to give.
 
Don, KD5NDB was very correct on the need for a blocking diode to be  inserted
in series with each solar panel when multiple panels are in use,  otherwise a
panel in shade where the other(s) are in illumination, could  absorb the
power being generated by back feeding into this panel.
 
Larger sized panels normally have the blocking diode included inside the  
panel assembly or terminal box. In addition they have  internally what I believe
are called bypass diodes to prevent the  panel limiting the voltage within
itself when part of the panel is in  shade where the rest is illuminated.
 
Bob, G3VVT
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[Don Brown-4]

Hi

Thanks for your input and this is exactly the method I use to check my
panels. I just suggest the resistor method because some DVM's do not have
current ranges and the possibility of damage to the current ranges if the
wrong range is used. Measuring current with a DVM is always a possible
problem if you forget the meter is on current and then measure a voltage
source. Most meters are now protected with a fuse but it is a hassle if the
fuse blows. The resistor method is safer but not necessarily better.

Don Brown




----- Original Message -----
From: <[hidden email]>
To: <[hidden email]>; <[hidden email]>
Sent: Wednesday, June 22, 2005 12:20 PM
Subject: Re: [Elecraft] Using the KX1 on Solar Power

>
> In a message dated 22/06/05 15:26:09 GMT Daylight Time, [hidden email]
> writes:
>
> You can  test the output current by connecting a 10 ohm 5 watt resistor
> across the  panel and measuring the output voltage
>
>
> Reply: .....................................................
>
> In practice you do not even need to do that.
>
> During some commissioning of a large solar powered microwave system I was
> involved with about 5 years back that used up to 15kW of solar power  at
> each
> site (200 x 75W 12V solar panels), the contractors who installed the
> system
> tested the output by connecting an ammeter effectively directly across
> the solar
> panel output terminals. When I raised the question would this not  cause
> damage? They came back quite rightly, no, the current will limit at what
> the
> solar panels are capable of providing. In these installations  the total
> array was
> divided into 12 banks of 48V sections with panels in series  and parallel
> to
> make up the arrangement. As the current involved was  considerable the
> method
> involved was to place a heavy gauge piece of wire after  the solar panel
> breaker and when the bank was activated measure the  resulting current
> through the
> piece of wire with a calibrated AC/DC clamp type  current sensor and a
> DVM.
>
> With the type of solar panels normally used by hams, probably a  DVM on a
> suitable current range direct across the solar panel terminals would do
> the job.
> You have to take care that the panel being tested is isolated from all
> other
> power sources such as batteries, but at the end of the day the panel will
> not supply any more than what it is rated to give.
>
> Don, KD5NDB was very correct on the need for a blocking diode to be
> inserted
> in series with each solar panel when multiple panels are in use,
> otherwise a
> panel in shade where the other(s) are in illumination, could  absorb the
> power being generated by back feeding into this panel.
>
> Larger sized panels normally have the blocking diode included inside the
> panel assembly or terminal box. In addition they have  internally what I
> believe
> are called bypass diodes to prevent the  panel limiting the voltage within
> itself when part of the panel is in  shade where the rest is illuminated.
>
> Bob, G3VVT

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