As a background on myself:
My name is Eduards, and I live in Ireland. I'm in university and am in my final year of Electronic and Computer Engineering masters. I just recently purchased my first car a couple months ago in June. A Honda Civic 2008 Hybrid, 2nd Gen IMA system.

When I purchased it, it had issues with the battery. Mainly the IMA light was on. After a few days of being unused, it wouldn't charge my 12V Battery anymore. Using an OBD scanner, I figured out it was due to a battery module voltage difference being too big, and that definitely was the case. I ordered some SkyRC Imax chargers, as well as some knockoffs to speed up charging. I disassembled the battery and charged the modules individually in the casing with a fan blowing for cooling at it. I charged at about 4.5 to 5 A and stopped charging when the voltage level was not rising for about 10 minutes, this was around 17.8V and later 18.4 V on subsequent cycles. I made sure the modules were never too hot to the touch. I also discharged at 0.5 A to about 10.8 V. I did this for about 3 cycles. This fixed the battery, and it actually performed a lot better than when I got it. Assist would last for a long time when flooring the pedal, and I had no recalculations too. This lasted for about 2 weeks until the car was outside for 2 to 3 days in the hot sun (the car is black), it's worth noting I drove the car every day. But on these days the car was outside in the sun, the inside of the car was extremely hot on entry. And after these 3 days I started getting several recalculations, until finally I got the yellow IMA light again. The code I get now is P0A7F. I checked all of my module voltages and they are all close to each other now. Here is some data I collected during a drive.

Mod 1 - 16.3 V Current 17.93 V Max 14.67 V Min
Mod 2 - 16.4 V Current 18.04 V Max 14.76 V Min
Mod 3 - 16.3 V Current 17.93 V Max 14.67 V Min
Mod 4 - 16.4 V Current 18.04 V Max 14.76 V Min
Mod 5 - 16.4 V Current 18.04 V Max 14.76 V Min
Mod 6 - 16.2 V Current 17.82 V Max 14.58 V Min
Mod 7 - 16.3 V Current 17.93 V Max 14.67 V Min
Mod 8 - 16.4 V Current 18.04 V Max 14.76 V Min
Mod 9 - 16.5 V Current 18.15 V Max 14.85 V Min
Mod 10 - 16.4 V Current 18.04 V Max 14.76 V Min
Mod 11 - 16.4 V Current 18.04 V Max 14.76 V Min
Total - 180.42 V Current 198.462 V Max 162.378 V Min

I also measured the internal resistance of all of the modules when cycling them, and they were all around 1-7 mOhm when charged. All modules were between 5400 - 6200 mAh on discharge immediately after charge. I understand that I should also test this a good amount of time later to see the discharge rate, that is one thing I have not looked at yet.

But otherwise, these numbers seem good to me? What do you think? I'm puzzled as to why I am getting the issue now. Was it the heat? Disconnecting my 12 V battery to force the car to charge the hybrid battery a couple times does yield some nice results with decreased to no recalculations, and noticeably improved performance.

I don't have any experience with grid chargers, and from what I can see, they're all sold in the states?

Any help is appreciated, I also emailed Peter Perkins. From my readings, I see S Keith is a wizard at this too.

 

Heat will destroy an HCH2 battery. They completely screwed up the cooling system dynamics and managed to create 132 hot spots in the pack. As such, the longevity of these batteries is poor.

By "Current" I assume you mean resting? If so, voltages sitting at 16.2-16.5V are not a good sign. A truly healthy pack will typically be inside 0.1V deviation. An okay pack will be 0.2V.

Unless the min and maxes were captured at the exact same moment, or are plotted vs. time, they really have little value, though seeing 0.3V deviations on both is not encouraging.

Unfortunately, the Imax B6 and similar are just plain junk and mostly useless for this task. The SkyRC units are quality, but there's a lot needed to make sure you get good performance. The type of lead you use is very important. Alligator clips are crap. Ring terminals are okay. The bullet connectors on the charger can be both...

Resistances of 1-7mΩ are simply wrong. Often these tools may be wrong, but they may be consistent and useful to compare to each other. Unfortunately, 1-7mΩ is neither.

The most important information you could provide is the as-removed resting voltage of each individual stick (2 per module, 22 total) before you started anything.

A Meanwell LPC-100-500 and a 400V/1A diode on the (+) line to prevent the battery from damaging the power supply is a very useful grid charger. You will need to pull the pack out of the car and provide supplemental cooling. The HCH2 cooling fan is PWM controlled, and it's a little difficult to drive. You would charge for 5500mAh * 1.6 / 500mA = 17.6 hours with active cooling the entire time. A box fan blowing through the pack is typically sufficient and it's okay if you feel comfortable heat coming out the discharge side. Once charging is complete, you can discharge with a low wattage (40-60W) tungsten or halogen bulb until you reach 66V, then repeat the grid charge.

The chances of you recovering this pack are miniscule, especially after the haphazard cycling you did.