So, I had the time to put the pack in the car today ... and there are more problems now.

When I started the car for the first time, it used normal engine starter and engine and IMA lights were right on (I had the 12V battery out of tthe car for whole week, so they were definitely cleared).
The OBD reader displayed:
P1600
P1601
P1435
P1570

Then I pulled the 10A fuse #9 in engine compartment to reset the computer. After starting the car again (normal starter used again) I got these codes:
P1600
P1601
P1570

When I turn the key, I can hear the IMA relay in the back, but when the engine is running the IMA battery is not supplying the power from the terminals (it reads around ~80V in idle; what engine supplies).I also checked the 10 voltage readings from the BCM connector and they are all good (16,05V-16,09V; I can post full list if needed). The 12V is being charged only in the limited range (1500-3000) as expected.

Before I did this last "session" with the battery reconditioning, the IMA motor was starting the car nearly all the time, and also readings on the IMA battery terminals were around 170V, even though the batter technically didn't work (IMA motor was disabled).

 

Hmmm... you might have blown the main fuse. Rare, but it's happened. There are two fuses on the junction board. The main fuse is under a plastic cover. Remove both fuses and check for continuity/resistance.

 

I checked them both yesterday. You think they might get blown today when starting the car?

The one in the bottom (100A) has to be fine, otherwise DC/DC conventer wouldn't work I guess.

 

Just checked both of those fuses and there is continuity.

 

A persistent P1570 with good tap voltages is most likely a failed MCM (motor control module) IIRC, it's the box the tap connector plugs into. You should be able to pick one up cheap at a salvage yard.

One thing to note is that if you replace the MCM: it may create a new issue. In mid-2004, they removed the PTC strips from the pack and patched the BCM (in the MCM) to expect open circuit. it will throw a code if it sees your PTC circuit. Alternatively, if you don't have the PTC strips, an OLD MCM will throw a code because it measures open circuit when it's expecting a resistance and will throw a code.

Summary:

Old MCM needs the PTC strips intact OR a 20-30Ω resistor spoofing the MCM.
New MCM needs for NO PTC strips to be present. Honda released a service bulletin instructing that the red wire snaking through the orange end plate be cut with 1" removed. You could simply detach one end of the cable and tape it off thus breaking the circuit.

 

Persistent P1570 with good tap measurements + the testing you've done means fuse issue is unlikely. Good time to confirm they are very low resistance, likely < 1Ω

 

How does the MCM fail? Did it literally fail today or how that happens? The last time I had pack in the car it was working, but the battery pack was the problem. Can I somehow check that the MCM is indeed a problem, or the error code is the only indicator we can depend on?

And can I somehow check which "edition" of the MCM I have? I see that the part number written on MCM is 1K000-PZA-E02.

Unfortunately, these cars are very very rare here (I literally saw 1 besides mine in the last 10 years), so I will have to order it online, if I decide to go that way.
I checked eBay and I can get it for around €80. I'm thinking to order one where seller offers return policy, in case the MCM was not the problem.

EDIT: I started the car again after checking the fuses and the OBD codes are the same three (1600, 1601, 1570); they were reset beforehand of course.

 

At this point, I can only go on the symptoms and codes provided. Initial symptoms and probabilities suggest battery. Initial battery data suggests the battery was in a substantial state of imbalance, and the post-recondition results were inconclusive.

After the prescribed testing, I am HIGHLY confident that the battery STICKS performs as needed in the 3 primary areas: self-discharge, resistance and capacity.

Per the service manual, there are only three possible outcomes of a P1570:

Bad connection (plug you're measuring voltages on)
Bad Battery
Bad MCM

The diagnostics instruct the tech to "update" the MCM, but that requires programming capability, so I'm disregarding it.

The MCM part number may not matter as they can be updated, so even if you obtain the same P/N, you may have the PTC circuit mis-match.

Prior to replacement, you could attempt disassembly and inspect for burned circuitry or cracked solder.

There's usually an associated code, but you could have a short between your HV circuit and the PTC circuit. With the junction board off, check for voltage between the ends of the stick bolts and the PTC strip. You shouldn't have any. This condition is almost always associated with some kind of obvious contaminant - usually a white powder that is dried electrolyte.

 

Thanks for all these infromation.

So tomorrow I have a plan to go in car again and do
a) Check again all readings on the BCM connector.
b) Open the MCM and try to locate anything "suspicious".
c) Check for the short between HV and PTC. If I understand correctly, I take of the black thiing and then check for voltage between the stick's terminal and that green strip below (without removing the orange board)? And I do this only on one side, or also on the back? When I was assembling the pack 2 days ago I inspected every stick and didn't notice any white powder or any other dirt anywhere.


What do you mean that diagnostics instruct to update MCM? So the problem with MCM is not hardware related?


And regarding this PTC strips. My pack has them and I didn't find any wires cut. Does that mean that my car uses the older MCM?
Now I was thinking, could it be something wrong with PTC strips and then the circuit is broken? How would I check that they are all operating fine.

 

c) Actually, you could just pop off the back cover since that's quicker and easier. Pick one of the PTC strip screws and check all 20 stick bolts for voltage to it.
d) The dealership can reprogram the MCM. "update" basically means they re-upload a fresh copy the MCM software. They may or may not upgrade it in the process.

e) If you pull the junction board and measure resistance between the two ends of the PTC circuit (two ends of the red wire), you should measure somewhere around 10-40Ω. Very high is bad and open circuit is bad. BUT a fault in this circuit should throw a code specific to this issue.

I'm concerned that we're dealing with something beyond what your code reader can read unless you're using something specific to Honda or a "professional" grade code reader (something expensive).

I think it's also prudent to "blink" the codes by shorting two pins of the OBDII port with a paperclip. The process is as follows:

http://99mpg.com/categories/insight/readingtheblinkcod/

NOTE the codes are only for the G1 Insight, so let me know how many flashes you count out. I often video it with my phone to insure I'm not making a mistake or missing a code. We are primarily interested the IMA light blinks with the check engine light as a secondary interest.