PD or Iota for my upgrade?

DryCamper11 wrote:

I agree. I'm willing to learn, but I see no way that the converter can output full power to a conventional resistive load bank (commonly used to test the output capabilities of devices like RV converters) and then turn "wimpy" and suddenly be unable to output the same power to a battery load.

Welcome to the REAL world. Here's what the PD does in an RV.



Stock Winnebago converter cabling. Cable resistance to battery is probably around 20 mohm. 60A PD quickly drops to 23A and tapers from there. 2 x G24 batteries discharged to 50%



Possibly Bigfootford's rig. Resistance about 10 m ohm. 2 x G24 (high quality batteries discharged to 50%.



Fisherguy got the best results from a 80A PD. Still, the converter never outputs 80A into 2 6V GC batteries at 50% SOC. Cable resistance is about 5 mohm.



My 55A Iota. Two golf cart batteries discharged to ~50%. ~5 mohm cable resistance. Converter remains in boost for about 2 hours.

In every case the PD fails to increase output voltage in order to hold rated current. The front end of the PD (ac power quality) may contribute to the problem, but something else is probably going haywire. Current control and voltage regulation centers around the error amp. The output voltage slowly creeps up to 14.4V. This is not normal when current tapers. The error amp circuit may be designed poorly. The circuit is possibly unstable. I would trace out the error amp circuit. I did that for my old 7347 converter. I modified it so that it outputs 13.7V at the battery and not at the converter. This eliminated a large cable voltage drop in my MH. Here's what the circuit looks like. The PD should have a similar circuit.



Sal

Edit: Added Fisherguy's and Iota plots.