Hello, I'm experiencing an issue with my new charge controller. I would like to ask the more experienced members of this forum for a sanity check, just to make sure I am not missing something simple.
- I have a small 12v LiFePO4 battery and many small panels, all the same model, ~22Voc, ~18Vmp.
- When I wire two such panels in series for example, I read a Voc of ~30 on a cloudy day like today from the ends of my PV wires.
- When I connect those exact same PV wires to my Victron 100|50 charge controller, I read a voltage of 13.2V from the PV connection terminals.
So, obviously PV voltage=Voc will only happen when the circuit is open. But why is my voltage dropping all the way from 30 to 13? This is far more of a voltage drop than I would expect from two of these panels in series. The one-way distance from panels to charge controller is only 2 meters. This change in voltage is observed simply by removing one PV wire from the charge controller, marking 30Voc, then plugging the same cable into the charge controller, and marking 13.2V.
I have checked, re-checked connections for anything that is loose or high resistance, but even with the PV leads jammed back into the terminal as far as they'll go, and clamped down to manufacturer torque specs, I get 13.2V. Would using a ferrule on the end of the PV leads help at all?
For another piece of evidence, consider this test. I put a piece of cardboard over one of the panels and plugged that sole panel into the charge controller. At the PV leads directly, I read 5V. From the charge controller, I read 5V. It almost feels like the PV voltage is being capped by my battery voltage (currently 13.3, but maybe that's just a coincidence).
Is this expected Vmp? Do I just need to wire more panels in series? Or is something potentially wrong with my controller. Thank you very much for reading this far
TL;DR: I'm reading 13V PV input as soon as I plug into my charge controller, whereas I read 30 Voc unplugged. Is this normal?
- I have a small 12v LiFePO4 battery and many small panels, all the same model, ~22Voc, ~18Vmp.
- When I wire two such panels in series for example, I read a Voc of ~30 on a cloudy day like today from the ends of my PV wires.
- When I connect those exact same PV wires to my Victron 100|50 charge controller, I read a voltage of 13.2V from the PV connection terminals.
So, obviously PV voltage=Voc will only happen when the circuit is open. But why is my voltage dropping all the way from 30 to 13? This is far more of a voltage drop than I would expect from two of these panels in series. The one-way distance from panels to charge controller is only 2 meters. This change in voltage is observed simply by removing one PV wire from the charge controller, marking 30Voc, then plugging the same cable into the charge controller, and marking 13.2V.
I have checked, re-checked connections for anything that is loose or high resistance, but even with the PV leads jammed back into the terminal as far as they'll go, and clamped down to manufacturer torque specs, I get 13.2V. Would using a ferrule on the end of the PV leads help at all?
For another piece of evidence, consider this test. I put a piece of cardboard over one of the panels and plugged that sole panel into the charge controller. At the PV leads directly, I read 5V. From the charge controller, I read 5V. It almost feels like the PV voltage is being capped by my battery voltage (currently 13.3, but maybe that's just a coincidence).
Is this expected Vmp? Do I just need to wire more panels in series? Or is something potentially wrong with my controller. Thank you very much for reading this far
TL;DR: I'm reading 13V PV input as soon as I plug into my charge controller, whereas I read 30 Voc unplugged. Is this normal?
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