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Post by brianrhea on Jun 5, 2017 14:15:13 GMT -8
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Post by rabird on Jun 5, 2017 16:23:35 GMT -8
look at the diagrams on page 5 of your linked doc.
A 12v panel has a range from zero volts to 22 volts. That's 36 cell panel
24v or 60 or 72 cell goes up to 40+
They make panels with more cell than that.
connect panels in series and the volts are additive, same current.
the rover can handle up to 100v input
So depending on what type of panel, how many, how they are connected and/or controller mode would change the LCD display
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Post by brianrhea on Jun 5, 2017 18:55:03 GMT -8
Thanks a ton! That's really helpful and makes total sense. I've only got one panel, so if I'm in the 17-19 range then that would seem like I'm doing alright.
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Post by rabird on Jun 6, 2017 5:39:04 GMT -8
mppt controller scans the panels and find mppt, it then operates at mppt till the batt gets to set pt of say 14.4v
Then the controller turns on/off to keep 14.4v, this is constant voltage CV, the current tapers as the OFF time increases.
ON, controller is at last mppt, OFF, controller is at Voc (~20v).
ON/OFF is at high frequency, faster than a voltage meter can read so ya get a average.
As the OFF time increases the displayed panel voltage should increase since OFF is ~20v.
If on/off were equal, mppt =16v, Voc=20v then the panel voltage should display 16+20 /2 or 18v.
After the time limit @ set pt 14.4v, a new set pt is used, FLOAT.
mppt and Voc are moving targets with various amounts of sun, panel temp etc.
I suggest ya monitor batt voltage, with enough sun and limited load it should rise to set pt (temp adjusted) and stay there the appropriate amount of time then drop to FLOAT and stay there. Charging current before it gets to set pt is an indication of sunny it is or how much sun the panel 'sees'.!
using loads during float or CV is possible, it first uses the excess not needed to keep CV and then discharges the batt if the load is larger than what the batt needs and the panel 'makes'. The drop in voltage @ batt from loads can cause the controller to start over!
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Post by brianrhea on Jun 6, 2017 7:49:31 GMT -8
"The drop in voltage @ batt from loads can cause the controller to start over!" This is interesting ... so I'm not using the "Load" terminals on my controller at all. I simply have the panels going in to the controller, and the controller going to the battery. And then, we just go on about our business in the popup as we normally would. During the day, this typically only includes running the roof fan (not the big a/c) for a little circulation and the water pump at meals if we're boondocking (which is most often). Do they make "switches" that would allow me to choose if I want to draw power from the Controller's Load or from the battery? You're very helpful by the way! You should offer 30-minute video chat consulting packages!  |
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Post by rabird on Jun 6, 2017 8:22:42 GMT -8
you have it connected properly.
The load knows nothing, nor the batt or the controller.
if the batt will not accept current it is available for use by 12v item in the PU.
Start over = Boost return voltage is 13.2v. This means if in FLOAT, the controller with 'start over' if the batt voltage drops to 13.2v.
Let's say your batt is charged by noon and is being floated @13.8v, ya trun everything on and somehow get the batt down to 13.2v, the controller will then start over and attempt to get the batt to 14.4v and then hold it there 2 hrs.
This is not a problem, the same thing happens at night, the batt voltage naturally drops and the controller starts charging when there is sun.
I camped in a PU and brought along a 15w panel, it provided about 1/2 my daily usage so I could extend stays, other trips I didn't use more than one LED light for 30mins a day. I did use that panel as a maintainer while the PU was garaged and the panel was outside.
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