As I said, welcome to the real world of PD converters! The second plot is very similar to the first. The first is just a bit more exaggerated. Nothing strange is happening to the cable, battery or meter. It's the converter!!!
Go and measure your PD. Take a look at the error amp circuit. The PD is is doing a very poor job of current and voltage regulation.
DryCamper11 wrote:
That just doesn't make any sense. The battery is supposed to be at 50% SOC. If the converter is putting out 13.5 volts initially, and the battery is accepting near 44A, it just shouldn't drop in current over a period of a few minutes as the voltage increases unless something really strange is happening to the cables or battery, or the meter is funky.