re:[Elecraft] Using the KX1 on Solar Power
Michael Donna Heit [EMAIL PROTECTED] wrote : 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. I do this all the time with my KX1. I use a 2ah Gel cell, a Micro M+ Portable charge controller from Sunlight Energy Systems and a 5W flexible Coleman PV panel that folds up to about the size of a hardcover book. This adds very little bulk or weight to my portable setup. You could easily get by with a lower wattage panel as the average current draw of the rig is probably just a bit over 100 milliamps, depending on how you choose to do the math (ie what figure you use for %TX time). The current draw figures for the Rig are about 40ma for RX and 650 ma for TX. As long as you are putting about 100 ma, or a little more, back into the battery via the PV panel you should break even. With a smaller panel you probably don't even need to bother with a charge controller. One advantage of doing this is that the rig sees a fairly constant 13+ V DC in and will run at full power, at least while the sun is shining. Michael VE3WMB P.S. The Volkswagen panels should be idea for this application and they are cheap (often free from VW dealers, if you ask nicely, or inexpensive from Ebay). BTW there is a QRP Solar Power Yahoo! Group if you are looking for more detailed answers. ([EMAIL PROTECTED]). ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
Re: [Elecraft] Using the KX1 on Solar Power
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 [EMAIL PROTECTED] To: elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
Re: [Elecraft] Using the KX1 on Solar Power
In a message dated 22/06/05 15:26:09 GMT Daylight Time, [EMAIL PROTECTED] 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 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
Re: [Elecraft] Using the KX1 on Solar Power
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: [EMAIL PROTECTED] To: [EMAIL PROTECTED]; elecraft@mailman.qth.net 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, [EMAIL PROTECTED] 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 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
Re: [Elecraft] Using the KX1 on Solar Power
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 [EMAIL PROTECTED] To: elecraft@mailman.qth.net 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: Elecraft@mailman.qth.net 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 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
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: Elecraft@mailman.qth.net 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
Re: [Elecraft] Using the KX1 on Solar Power
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 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
