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G, you have to throttle back a bit on the pictures. Once they get a thousand(?) pixels wide they blow out the whole page and that makes everything impossible to read without scrolling. The fault of the forum software, for not downsizing the images, but you can help that.
Cam-
"What IS puzzling to me is that we never saw 14.4-14.5 V level charging out of the controller. I think the closest you got was one 14.2 reading. Is this a function of the controller that can be changed or was mis-adjusted."
The controller is very adjustable. In the second run--the more recently posted raw data--keep in mind that I had it programmed for an AGM battery rather than the wet lead, so yes, some targets are lower. For the AGM bulk is set to 13.6 and acceptance to 14.4, and it was still in the bulk phase.
"http://userwww.sfsu.edu/~ozer/engr300-solar1N.pdf ...
The student experiment ...is a bit flawed for our purposes since they eliminated all reflection and did not place a load on the cells …...These are less than the losses you showed...does show BOTH that the ability to tilt and position matters a great deal during the day AND that normal swinging at anchor can also have a great effect. No surprises there.
My guess is that with a real load…the voltage would behave in a similar manner but we have no solid data to support that…though your data would suggest that is true. You ought to write them and suggest THAT experiment for next year!! "
ROFL. No corresponding address. With any luck they will go to work someplace besides NASA.< g > I can confirm from my own second day of testing, that with a real load the voltage does go down similarly. As it did in low-light, when the panels were loaded.
"Caution….MATH FOLLOWS!! (G)"
Wait, I'll put on my bunker gear and thermal goggles.
"According to the experiment…both POWER and CURRENT are a COSINE function of the angle of incidence.
...Cosine of 10 degrees is .985 so multiplying by 100 watts gives you a maximum of 98.5 watts…a 1.5% loss.
20 degrees=6%, 30= 13%, 40=24% etc. etc."
...But if as HS suggests…both amps and voltage drop in a cosine like manner…then power drops quite a bit quicker since power then would be:...
Since we don’t have actual data measurements of both approaches in a controlled environment, it seems to me that we only can safely say that getting off axis by 20 degrees…(or about 100 minutes without adjustment) causes between a 6 and 12% drop from maximum output."
Obviously, these need to ship with a "panel monkey" that can sit up there and adjust the panels every hour or so in exchange for a food pellet. Perhaps the unemployed Capuchin (?) monkeys that are no longer able to find work with organ grinders?
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"OK…When faced to the noon sun at the ANGLE of Latitude…
A 100 watt panel gives 1200 watt/hours in a 12 hour day…and 60% would be 720 watt hours. At 13.6 volts this would be 53 amp hours per day (on a perfect day and assuming no conversion losses.)"
So you are suggesting an output equal to ~seven hours of sunlight, versus the common six hours suggested here and there, for tropical locations.
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"...(Check my math, but that's what I wrote at the time.)
OK…so you have panels putting out 69.6 watts. ...Thus in this example the Sboost provides a 6.8% gain in power delivered to the batteries over a conventional 3 stage regulator.
Even though I think we each got there differently….out numbers agree! (G)"
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"11AM
13.5V @ 3.1A angled to sun
moved 45d away dropped to
12.5V @ 2.5A
10% loss.
….umm …that is a 25% loss of power AND 12.5V means nothing is going into the battery. Is that voltage a typo?"
Nope. Read it from the panel's display. It did not like being angled 45d away from the sun. My direct readings (multimeter) are four digits, the SB's are 3-digit. Maybe the sun ducked for just the wrong moment behind a small cloud while I was looking the other way?
...
"1:10PM
14.2V @ 3A /vs/ 14.1 C @ 2.7A (42.6 Watts)
14.2V @ 3A direct /vs/ 14.1V @ 2.7A aimed 10deg. Off
Another 10% loss but finally we see 14+ Volts to the battery. Any time the panel is being fully driven in bulk charge mode we should be seeing over 14V if we are to expect our batteries to last. We need to understand better why you are not seeing 14+ more of the time. 13.6V is absorbtion level voltage. ?"
It does seem odd, I can only speculate as before that the charge algorithm is set up to supply amperage first, voltage second, and to supply just "battery plus xx%" voltage in order to maximize the amperage. Both the display and indicator lights indicated BULK not ACCEPTANCE in that phase. And bulk was set for 13.6 for the AGM battery I was using, per the manufacturer's recommendation that anything above it would not contribute to the charge.
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"Finally, you responded to Amy saying:
batt voltage: 12.2 to 12.3
...The numbers tell me that your batteries are nowhere near full, so ..."
"I would suggest that the real answer lies in the fact that there was stuff running on the boat and that the numbers reflect that...Amy can correct me if that assumption is wrong and everything n the boat was shut down."
If you expect her to take notes, you may have to send her a notepad.< g >
"This continues to be most interesting."
NOW, to apply for the government grant money. I'll have to ask the folks at Sandia if they've got any budget left.< G >
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