On 2/13/19 at 9:56 AM, mpilg...@bellsouth.net (mjpilgrim) wrote:
I've employed a small solar power system to supply my ham shack which
includes K3-100/P3, two PCs with flat screen monitors, and 20" flat screen
TV. This began as a basic test bed to understand Solar Power, so i know i
have lots to learn, and perhaps I have answers to help others with the same
interests.
I have been using a solar system with my station for 5+ years. I
use a charge controller from CirKits
<http://www.cirkits.com/scc3/> for my lead-acid AGM batteries. I
have about 135 AH of battery and about 10-15 A of "12V" panels.
(Note that the capacity of lead-acid batteries is much less than
what is advertised. Ditto for the current from solar panels. The
LiFeSO4 batteries seem to deliver closer to their specification.)
I power the K3, P3, antenna switch and various other things from
the solar system. My laptop and the SVGA screen for the P3 run
off mains power. I am in the process of setting up a 10"
HDMI/VGA monitor that will run on 12V at 700-800 mA from
Adafruit as a second monitor for my computer. It may also work
as a SVGA monitor for the P3, but hasn't been tried yet.
If the batteries are fully charged I can operate a weekend SSB
contest, assuming normal sleep and contact with the family.
Operating QRP will go for a long time.
The charge controller can handle up to 20A of charge current,
with modifications for 40A and 60A. The fact that the
modifications include changes to minimize RFI gives me a warm fuzzy.
I also use a boost regulator to give my K3 about 13.5 volts.
Mine is a TGE N8XJK Boost Regulator, which mostly works. It is a
"20A" unit and tends to overheat and pop its 30A breaker when
running with low battery voltage in high demand modes like FT8.
Also, all the chip numbers have been scratched off and there is
no circuit schematic. I would look for a different boost
regulator if I were buying again.
A big deal everywhere is voltage drop. If you have 0.01 ohms
between the charge controller and the batteries, and they are
charging at 10A, them you will get a 0.1 volt drop in that line.
If the charge controller is sensing battery voltage at its end
of that circuit it will be off by 0.1V. Since the float voltage
for my AGM batteries is between 13.4 and 13.6 volts, small
values of resistance can lengthen charge times. (The charge
controller thinks the battery voltage is higher than it really
is, and cuts charge current. With less voltage drop, it raises
the charge current. etc. etc.)
I'm thinking of trying a modification to the CirKits charge
controller to use a separate wire between the battery and the
voltage sense circuit, but haven't gotten around to it yet.
73 Bill AE6JV
I'd like to hear of your trials, errors, and decided solutions for best
results. I'm now researching best price performers for a pure sine wave
inverter so i can merge my ATT u-Verse gateway/wi-fi and
associated devices. Also, when running CW on the K3 i
occasionally encounter LOW BATTERY error,
requiring a few seconds of UP-Key to allow the batteries to recover. I'd
like to discuss that symptom relative to my sizing considerations in the
Solar Power system. On paper it appears sufficient. Sometimes i
wonder............
Drop me a note via email so we might continue this conversation
at length. Thanks. Mike, K5MP
-----------------------------------------------------------------------
Bill Frantz | "The only thing we have to | Periwinkle
(408)356-8506 | fear is fear itself." - FDR | 16345
Englewood Ave
www.pwpconsult.com | Inaugural address, 3/4/1933 | Los Gatos,
CA 95032
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