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4564Re: [ScoutRadio] Re: Blinker Morse App (USB charger) solar

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  • Steve
    Aug 9, 2014
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      Nice link.  Great starter projects. 

      For those scouts that are not DIY types, I have been using manufactured solar panels for a number of years.  I have a top quality 75 watt panel that gives me 3.5 amps of charging power that works great for a marine battery to run a 100 watt radio.  It isn't backpacking gear.  If someone wants more information about the solar panel system as I used with my pop-up camper for "dry camping" at star parties, I have a nice document (it was on a web page) I can email it to you. 

      For most of my scout camping trips, I have three other small solar panels I use.  Two panels are ten watts and one is five watts.  My original 10 watt panel is a 36 cell unit mounted on a metal plate that I used to charge a gel cell battery (with a Micro M+ charge controller http://www.theheathkitshop.com/page14/index.html) for the K2 radio at many summer camps.  The charge controller doesn't cause RFI and is reasonably priced (although out of stock right now).  The charge controller allows me to set the panel in the sun and forget it without worrying about overcharging the battery.

      With the procurement of a KX3 to my QRP gear, I wanted a physically smaller solar panel.  The KX3 has internal rechargeable AA's and a charger.  The radio can handle 15-16 volts max and the PowerFilm folding solar "panels"  are in that range too.  The spec for the 10 w panel is 0.6A at 15.4V's and my measurement of VOC = 18.42V.  I started with a 5w panel from Amazon (works great with 0.3A) and I purchased a 10w panel at dayton this year for $130, see: http://www.amazon.com/PowerFilm-Foldable-Solar-Panel-Charger/dp/B002LCEQPU...  I have connected the solar panel directly to the KX3 and monitored the voltage of the panel and batteries using the panel display.  This is my choice for day trips or backpacking (I haven't had a chance to try it backpacking yet).  That works well and keeps the required gear to a minimum.  I also use the radio with an external LiFe four cell battery, see: http://www.a123rc.com/goods-1575-8+PCS+26650+32V+2300mah+cell%28replacement+of+A123+26650M1-A+cells%29.html.  The solar panel and charge controller is used to "set and forget" with the LiFe battery pack, too.  I made the battery pack with two power leads.  One for the charger the other to the radio.  Since I "need" another charge controller I have been looking at this one: http://ki0bk.no-ip.com/~pwrgate/LLPG/Site/Solar.html if the Micro M+ is unavailable.  Both charge controllers allow setting the on/off setpoint for different batteries.  The A123's and the 12V lead acid gel cell batteries have a very similar charged set-point.

      At camp, I often charge the battery during the day (difficult to solar charge at night...) and operate in the evening.  I operated battery solar during Field Day and I had no difficulty charging and operating during the day and running off battery at night.  At the end of FD, the battery was still fully charged (clear sky's help!) using the PowerFilm 10w panel.

      73, Steve WB3LGC (KB3NCC at camp)

      BTW, PowerFilm makes an AA battery charger and a USB charger (to keep on subject), too. 
      http://www.amazon.com/PowerFilm-USB-AA-Solar-Charger/dp/B001RMBHMK

      On 08-Aug-14 3:16 PM, Robert Bruninga bruninga@... [ScoutRadio] wrote:
       
      Yes, the going best rate for large solar panels is about $0.60 cents per watt, but those panels weight 50 lbs and are too big for scouts to typically manage on a hike.  here are many places selling DIY kits which allow one to assemble their own  cells (not practical for home use due to the intense labor demand, but still good for a scout project for one small panel)

      Here are some:
      http://stores.ebay.com/HEARTOFTHESUN-SOLAR?_trksid=p2047675.l2563

      But notice the cost per Watt even in these HUGE labor intensive DIY kits is no better than the 300W panels fully assembled!
      By assembling one's own scout panel, you only need enough cells to get to 5 volts an then require only a simple 5V regulator instead of a very expensive switching regulator to get down from the 30V of he big panels.

      I assume these cells are still about 0.45v each at peak power?  In that case you probably should use 16 of them to get 7.2v which is perfect for a 5V regulator.  ANd makes a nice 4X4 array.  Bob, Wb4APR




      On Fri, Aug 8, 2014 at 1:48 PM, Doug Garman k7evi@... [ScoutRadio] <ScoutRadio@yahoogroups.com> wrote:


      Bob, you need to shop around for solar panels... I paid about $235 for a 330 watt solar panel. Charge controllers to bring these to 6 volts are already designed (you can use their schematics to build your own but not to sell).
      Higher voltage panels with power tracking means you get more charge from less light -- longer time FOR charging.  { I have been totally of grid for 9 years - so I have some idea of what can be easily done!  We run 2 100 W SSB rigs for some 48 hour HAM contests with about 400 watts of solar panels}






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