PD or Iota for my upgrade?

BFL13 wrote:
" As the current through the cables drops, the voltage drops accordingly."

Is that not the tail wagging the dog? I thought the constant current was the result of the voltage difference, and that diff was maintained by the converter staying ahead of the battery by using that feedback you have been describing (which is way over my head technically)

You can look at it either way - voltage drives current, or current drives voltage. In the end, all switching converters are just turning on/off and it's the duty cycle that controls both voltage and current into whatever load is attached.

In the quote above, I was just commenting that for constant current, you see constant voltage drop in the cables. As the voltage of the battery rises, eventually the converter approaches its target and the current drops, producing less voltage drop in the cables.

I thought the idea here was that the PD does not stay ahead properly like these two examples (Paramode and PowerMax---Iota and WFCO same thing) and you are trying to find out why.

Yes, that's one way to look at it. Another way is to say it's not pushing out enough current. The heart of the PD9200 series is a current mode controller. It measures the output current and controls that current according to several rules. The basic one is whether the output voltage is high enough. You can control how much current you want it to supply for any differential between target and the actual measured voltage (the "error signal"). The secondary rule is don't try to send more current than the current limit.

AFAICT, the difference between the PD and the others is that PD has it set so that it tapers off the current faster than the others. This isn't any inherent limitation in the power supply. It's just a setting for the controls that tell the controller what to do. For the majority of people who are plugged in fulltime, this may be much better for the batteries and life of the PD. It's only those like me who drycamp a lot and want to maximize the charge rate of batteries so that we can shorten the generator runtime who care about this. I'm willing to give up a bit in battery life by shoving in lots of current real fast if I can shorten my generator runtime.

Looking at the chart, I may save 10 AH in the first hour, 15 AH in the second and 20AH in the third by tweaking a few resistors. That's between a half and an hour of charge time that I can not run the gen. Plus, I've upped the target voltage, which will put a bit more energy in the battery tank. All this will save gas, add quiet and let me leave the vicinity of the RV earlier - all worthwhile goals. :)

I wouldn't do this if I wasn't curious, but it's more fun than watching TV. Plus, my new batteries gain capacity from a little exercise, and I'm giving them that by all the testing.