PD or Iota for my upgrade?

DryCamper11 wrote:

Wayne Dohnal wrote:
If I had the resources (which I don't) this is what I'd consider a minimal test for a high confidence comparison of a PD converter against another converter:

I agree, that would be a good test. I'd run that test with my PD 9280 against another converter, if I had one, but I don't. I've got four GC2's of identical age.

If the PD converter can't maintain its boost mode voltage, it's defective or there's some sort of converter-battery interaction that I don't understand. If the PD converter maintains the voltage and the current tapers more than with the other converter, there's something happening that I don't understand even more.

Agreed.

The converter behaving differently with a battery vs. a resistive load is IMO so bizarre that it demands squeaky-clean data. Doesn't mean it's not possible, it just begs a high level of proof to be believable.

That's exactly where I'm at.

I really appreciate that Sal has posted some "real world" data. I've seen it before, but it's nice to have it here. There are things that I just don't understand about it. For example, the chart marked PD9260 Navion "H" shows a drastic current drop from about 44A to 23A in the first few minutes. At the same time, it shows the converter and battery voltage climbing from 13.5V to near 14V.

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. It shouldn't matter what converter is supplying the voltage. If that's the real voltage, there's no way for the converter to hold that voltage and decrease current into the battery. If the converter was tapering current, it would do it by decreasing voltage. That's the only way a converter has to taper current, yet the chart shows the voltage going up, not down!

Something is seriously wrong there. Could the AC power be funky? Could the meter be wrong? Could the converter output be pulsing and that pulsing output is not being caught by the meter used to measure voltage? If the input of the PD was the problem, as has been speculated, I'd expect to see the voltage at the converter output as it failed to maintain the 44A output. That's not happening.

It's things like that that make me agree that careful and controlled testing is the only way to tell what's really happening. For that chart, something is happening behind the scenes.