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keljohnso
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# Posted: 23 Oct 2014 18:24
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I have a Renogy 200W setup with a Renogy 30Amp PWM controller.
With the panels disconnected I get like 20 volts from the panels.
When I connect the panels to the controller I get like 20 volts +/- at the connecting screws. But when I connect the controller to the battery, I get the battery voltage (12.4 +/-) at the connecting screws for the panels AND the screws for the battery.
Shouldn't I get what the panels are generating at the panel screws and NOT the battery voltage?
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MtnDon
Member
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# Posted: 23 Oct 2014 19:06 - Edited by: MtnDon
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When you connect a voltmeter across the pos & neg leads from the panels w/o the panels being connected to anything else you are getting what is known as the Voc, open circuit voltage. If the sun is full on the panels and bright your reading should be close to the rated Voc from the panel spec sheet.
Same thing when you connect the panel wires to the CC but have not connected the CC to any battery.
Once you connect the CC to the battery things change. The CC is now working. The voltage from the panels will drop down to something near the Vmp rating, if the sun is bright. However, I would not expect that voltage to fall right down to be the same as the voltage measured on the battery terminals.
If you connect the CC to the battery first, what is the voltage reading at the batteries? Usually the routine is to connect the CC to the batteries first. Unless the instructions for what you have state differently, that is what I recommend.
Then the PV output is connected to the CC input. The voltage at the battery should rise. To what reading depends on the battery state of charge and how much sun is on the panels.
Have you had this system up and running for a few good sun days? Without taking any power from the battery the battery should end up fully charged if things are working.
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keljohnso
Member
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# Posted: 23 Oct 2014 19:55
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Yeah, Ive had it working pretty good, then the sun moved.
The place has been empty for like 2 weeks and when we got there the battery voltage was only like 12.3 on 2 good deep cycle batteries. Even with the now shady conditions, I would think with nothing being used the batteries should be more like 12.8-13.1 like normal in the 2 weeks.
So in trying to check things out I found this funny voltage. Renogy thinks it may be shorted internally and wants to send me a new CC and have me send back the old one. I left the CC there and repositioned the panels for now, I'll go check it weekend after next and see what I get then. If things are the same, I'll send it back.
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MtnDon
Member
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# Posted: 23 Oct 2014 20:12
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Depending on what 'shady' actually means I would expect batteries to be full after two weeks of no loads being drawn on them and a working CC and panel set active. That could also vary depending on the state of charge the batteries were left.
Even with minimal sun on the PV the CC output voltage should be greater than the disconnected battery voltage. Maybe not enough amps to do much, but the volts should be more than battery.
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keljohnso
Member
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# Posted: 24 Oct 2014 08:29
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Thats what I thought.
The sun dropped so I had to angle my panels some. In a few weeks the leaves should all be off the trees and that should fix my "shady" problem.
I have an stupid automatic voltmeter so I can't check amp output. When we go back I'll see if it was just the panel placement, if I get the same results I'll swap the CC.
Thanks for your help.
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MtnDon
Member
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# Posted: 24 Oct 2014 10:23 - Edited by: MtnDon
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Meter that reads combination volt, amps, watts, etc. Very handy. You need to wire it up, I use Anderson power pole connectors and have a set of connecting cables made up with various adapters. You can wire it in and get both amps and volts all at once.
OR Sears has a great deal on a clamp meter that does AC and DC.
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