"I've repeatedly indicated the critical nature of getting all the codes read, which I have yet to see you produce."
I blew out my knee training and could not walk for a few days, so I was not lifting sh$t.. Got original battery pulled out this morning and apart to verify if it had a cut wire.
I'll get the other (2003) battery is asap and pull a code. I have a nice code reader for my SLK that may work, if not O'Reilly it will be. The P1600 code was from a cheap reader.

I wish I could give up and just retire the car but I don;t want to yet. It had been a reliable backup.

 

There is also a way to blink out the codes, which is better than most code readers. This is accomplished by shorting two pins on the OBDII port with a paperclip and counting the long (tens place) and slow blinks (ones place) of the CEL and IMA light. Some DTC can mean several different things. The blink codes narrow it down to a specific reason, e.g., on the Honda Insight, P1449 can mean four or five different things.

I don't have the specifics for the HCH1, but I have a manual on the way because I'm tired of not knowing the subtle differences between the HCH1, the G1 Insight and the HCH2.

 

After pulling the original 2005 battery and disassembling it, the only difference from it and the 2003(?) pqck was the 16Ω resistor. I used the EV Peak to charge/discharge sticks on the '03 for many days, removed the 16Ω resistor and no codes so far. Car is back to charging and assisting as it should. The 2005 sticks are not charging and discharging well but again, that pack has 310k and original.

The next goal is figuring out why the IMA fan is running full blast even after removing the Maxx Volts charger. It was fine until I installed it about a year ago and whenever key is on, it runs non-stop.

 

Glad to hear it.