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Author Topic: Solar SLA charging and maintenance for unattended transmitters  (Read 4660 times)

Offline Stretchyman

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Re: Solar SLA charging and maintenance for unattended transmitters
« Reply #15 on: February 21, 2019, 0924 UTC »
'It's better to give than receive' so why RX when you can TX!

                            Buy one from me, NOW!

Great discounts on ALL my transmitters if purchased via HFUnderground


                                              ;)

Offline JimIO

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Re: Solar SLA charging and maintenance for unattended transmitters
« Reply #16 on: February 21, 2019, 1301 UTC »
Nice! Only one problem: "Does not ship to United States"    :'(

Offline Josh

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Re: Solar SLA charging and maintenance for unattended transmitters
« Reply #17 on: February 21, 2019, 1648 UTC »
Also don't overlook the environment, moisture and critters will all be trying their best to get in and gum up the works. Also also the sun might try to make things difficult by heating things up that shouldn't be heated.

Wild wood rats are a real PITA. Had to use 1/4" tubular braided shield on solar panel cables

Some folks have found relief by smearing the cables and whatnot with hot sauce, the critters don't like that too much but it will have to be reapplied occasionally. Can also apply it to furniture legs that attract our four legged friends.
We do not encourage any radio operations contrary to regulations.

Offline Teotwaki

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Re: Solar SLA charging and maintenance for unattended transmitters
« Reply #18 on: December 17, 2019, 1734 UTC »
Some folks have found relief by smearing the cables and whatnot with hot sauce, the critters don't like that too much but it will have to be reapplied occasionally. Can also apply it to furniture legs that attract our four legged friends.

Hot sauce would be okay for a local site but the braided cover has ended my wood rat problems. No cables damaged in almost two years!
Jim
NRD-525, Elecraft KX3 and Elecraft PX3 Spectrum Display
76' end fed long wire & 66' off-center fed dipole for 10/20/40 meters
Orange County, SoCal, The better half

Offline Teotwaki

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Re: Solar SLA charging and maintenance for unattended transmitters
« Reply #19 on: December 17, 2019, 1746 UTC »
Another enhancement for remote battery powered gear is to add in a Low Voltage Disconnect. The SLAs will be damaged if repeatedly run down below 12 volts so I've tried some different circuits and finally settled on one based on the LM339 quad comparator IC.

I ended up choosing 12v as the cutoff point and 13.2v as the reconnect point as that is where the solar panel should be supplying some good current to the battery.

What I found is that the inverting comparator wants to switch very quickly but the battery voltage can get "noisy" with a discharged battery being ramped up quickly by a solar charge controller.  There was some "dither" at the 13.2v "ON" trigger point and I  I had to add in some capacitors to add in a small delay to the switching and make the on/off cycles cut over cleanly. The comparator's voltage reference is based on a low power 78L05 and the comparator's output goes low for the "ON" condition. That output is applied to pin 5 of the main IC (LM2596S-ADJ) in the switching regulator.

Jim
NRD-525, Elecraft KX3 and Elecraft PX3 Spectrum Display
76' end fed long wire & 66' off-center fed dipole for 10/20/40 meters
Orange County, SoCal, The better half

Offline redhat

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Re: Solar SLA charging and maintenance for unattended transmitters
« Reply #20 on: January 22, 2020, 1541 UTC »
This has stirred an interesting idea.  Use a prepaid lte modem to get an internet connection to the transmitter.  Have a raspberry pi or similar to poke an internet stream, and if available start up the transmitter and process the audio.  Should the battery get too low, throw noises in the audio and shut down.  A max time limit could also be placed on any day based on weather conditions.

+-RH
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Please send QSL's and reception reports to xfmshortwave [at] gmail [d0t] com

Offline JimIO

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Re: Solar SLA charging and maintenance for unattended transmitters
« Reply #21 on: January 22, 2020, 1939 UTC »
With an internet connection and a raspberry pi or similar you could do anything.
Got line of sight? Then you don't even need internet.

https://help.ubnt.com/hc/en-us/articles/205197750-airMAX-Which-product-should-I-use-

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« Last Edit: January 22, 2020, 1944 UTC by JimIO »

Offline redhat

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Re: Solar SLA charging and maintenance for unattended transmitters
« Reply #22 on: January 22, 2020, 2250 UTC »
The idea was to put something out in the hinterlands of nowhere.  Like the beacons of the SW, put it up in a state park, wilderness area, etc.

+-RH
Somewhere under the stars...
WinRadio Excalibur/305 w/ a chi-town resonant loop, Kenwood KDC-U356 for mobile listening.
Please send QSL's and reception reports to xfmshortwave [at] gmail [d0t] com

Offline JimIO

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Re: Solar SLA charging and maintenance for unattended transmitters
« Reply #23 on: January 22, 2020, 2348 UTC »
There's a # rapberry_pi channel on the HFU Rocket.Chat...    8)

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Offline JimIO

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Offline redhat

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Re: Solar SLA charging and maintenance for unattended transmitters
« Reply #25 on: January 24, 2020, 1452 UTC »
I think the power consumption vs performance would still be better with a pi which uses a maximum of 15 watts.  Power budget is pretty thin as it is, and no one wants to put up a 200W array to run this thing.  Either way, a big battery will be required, probably around 100AH.

+-RH
Somewhere under the stars...
WinRadio Excalibur/305 w/ a chi-town resonant loop, Kenwood KDC-U356 for mobile listening.
Please send QSL's and reception reports to xfmshortwave [at] gmail [d0t] com

Offline JimIO

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Re: Solar SLA charging and maintenance for unattended transmitters
« Reply #26 on: January 24, 2020, 1843 UTC »
When I wanted to start playing with single board computers I got one of these:

http://www.orangepi.org/orangepizero/

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Offline syfr

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Re: Solar SLA charging and maintenance for unattended transmitters
« Reply #27 on: March 11, 2020, 2204 UTC »
Hard to imagine that you'd need a Pi .  For beacon work, an Arduino seems more than enough .   There's more than enough IO pins to sense/control things.  You can put the thing to sleep in ultra low power mode (low single digits mA at LEAST  without a lot of work.
There's a LOT of capability in the nanos for $2. 

My .02

S.
NRD525/TenTec Paragon lotsa wires and some beams

Offline redhat

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Re: Solar SLA charging and maintenance for unattended transmitters
« Reply #28 on: March 11, 2020, 2216 UTC »
This was a hypothetical idea of placing a transmitter off grid and using 4G to get an audio stream, process, and transmit the program material.  An arduino certainly does not have the horsepower to do that.

+-RH
Somewhere under the stars...
WinRadio Excalibur/305 w/ a chi-town resonant loop, Kenwood KDC-U356 for mobile listening.
Please send QSL's and reception reports to xfmshortwave [at] gmail [d0t] com

Offline Teotwaki

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Re: Solar SLA charging and maintenance for unattended transmitters
« Reply #29 on: March 12, 2020, 0035 UTC »
This was a hypothetical idea of placing a transmitter off grid and using 4G to get an audio stream, process, and transmit the program material.  An arduino certainly does not have the horsepower to do that.+-RH

There are quite a few ideas floating through this thread. The OP asked for solar charging for beacons then one tangent was about Arduinos for CW then somehow audio streaming got worked in. If we don't quote who we are responding to it gets a bit confused   ;D

OP's message
Hey I'm planing on setting up some beacons sometime soon and I would like to pick everyone's brains in regards to solar charging some sealed lead acid batteries,  I'm looking at using a 7.2 AH 12V SLA, I haven't decided on solar wattage yet, I'm thinking I'll need about 12 to 16 watts of solar to charge, what have your experience's been with solar charging? what's the simplest charging circuit without sacrificing too much battery longetivity? I know its a compromise.
Jim
NRD-525, Elecraft KX3 and Elecraft PX3 Spectrum Display
76' end fed long wire & 66' off-center fed dipole for 10/20/40 meters
Orange County, SoCal, The better half