PWM input voltage, Xantrex C40 test video
here is the Video link, the fluke is plugged directly into the Solar panel drop wiring before it enters the controller right above the panel input protection fuse, that i use for a disconnect just c...
Forum Discussion
Looking at the schematic and believing MrWizard's reading this is what must be happening. Even when the controller should be on all the time, max charging, it is not. There must be a small time that the controller is off and the panel voltage is at V open circuit, the volt meter is averaging the voltage to get what MrWizard is seeing. This is not an uncommon situation with PWM. There really is no way to know really what the voltages are without using a scope and each brand controller could be quite different and still be called PWM.
Here is another question that I don't think has been asked. If the controller is pulse width modulating the panel voltage it also must be pulse width modulating the current to the battery. So the current that is being read as charge current is an average current, not a constant DC current.
MrWizard wrote:
"if you have a DC power supply with a voltage at a set voltage powering equipment that voltage will not change unless the load exceeds the ability of the power supply" TRUE
"the panels are a pure DC power supply the controller is the voltage regulator" FALSE -- the panels are current sources.
Here is another question that I don't think has been asked. If the controller is pulse width modulating the panel voltage it also must be pulse width modulating the current to the battery. So the current that is being read as charge current is an average current, not a constant DC current.
MrWizard wrote:
"if you have a DC power supply with a voltage at a set voltage powering equipment that voltage will not change unless the load exceeds the ability of the power supply" TRUE
"the panels are a pure DC power supply the controller is the voltage regulator" FALSE -- the panels are current sources.
