Originally Posted by Vermilye
... but why does it drop to 0 amps with the addition?
This might take a lot of detective work with a volt/amp meter.
Here is the key question: "What is even stranger is that if I unplug the portable panel, the GoPower controller jumps the current back to 2-3 amps of charging current".
- in no particular order:
Where is the unplugging/plugging taking place? Can you confirm that the wires
from the portable panel are still attached at the input to the GoPower? Unlikely,
but possible that at some point they were moved to the output side, which could
go a long way to explaining what you are observing.
Can you measure the voltage at that point before and after the plugging?
Can you measure the current - if any - coming out of the portable panel after plugging? Coming out of the GoPower (to verify the 2-3 amps)?
What is the voltage - using your voltmeter, not the GoPower - at the output terminals of the controller, and at the battery posts directly?
All these answers may or may not help. This is a good project to use up a cold, dreary mid-winter weekend.
In an ideal world you would substitute another GoPower in place of your current one and see if the behavior changes or remains the same.
Wether or not you settle on a definitive answer, you will be an expert at troubleshooting solar systems when you are done.