I recently bought a 2003 Civic Hybrid with the IMA light on and p1446 p1570 p1600 codes. The battery was replaced about 3 years ago (Dorman rebuilt unit) and the codes appeared immediately after going into the dealership to have the Takata airbag recall performed.

Pulled the battery pack and found really disparate voltages and three sticks have burn marks. From the contactor side of the battery I labeled the individual sticks from top left to bottom right, 1 through 20. Sticks 4, 16 and 17 are burnt, ech between cell 4 and 5. The voltages are as follows:
1: 0.37v
2: 0.40v
3: 0.37v
4: 3.88v burnt
5: 6.28v
6: 6.96v
7: 0.37v
8: 0.37v
9: 0.41v
10: 0.40v
11: 0.39v
12: 0.44v
13: 0.40v
14: 6.81v
15: 5.93v
16: 3.59v burnt
17: 0.28v burnt
18: 0.40v
19: 0.42v
20: 0.42v

I believe the previous owner drove the car with the IMA battery switch in the "off" position without unplugging the sensors to disable charging. My question is: what might cause that specific voltage disparity? Most of the service data I find on forums and YouTube is related to the HCH2 battery and I'm not sure how to diagnose potential problems in the contactor and control segment of the battery pack. Is it possible that driving the car with the IMA switched off caused the burnt spots on the cell? I'm concerned that simply replacing the bad cells won't actually fix the underlying cause.
TIA and I'll update as I make more progress on my own.



Edit: I'm going to cycle all EXCEPT the "burnt" cells with a 'Venom Pro2' rc battery charger and purchase a few loose sticks probably from eBay to condition and hopefully mix back into the battery.

Voltages from stick #1 in top left to #20 in bottom right

 

Answers to your questions:

Because they are garbage and they failed likely just outside the warranty period. The owner opted to ignore it and over the last 1-2 years, the cells have self-discharged into oblivion.

No. The burned spots on the cells are likely the original failure point.
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Unsolicited input:

Those cells are made by REO. They are junk. You are wasting your time, and you are likely going to cause one or more sticks to explode. I am speaking from experience and the experience of others with far more expertise than me who have exploded many more sticks than me.

Once the Chinese cells go < 1.2V/cell, they are DEAD. They can't be brought back. Period. They are different than the Panasonic cells. There are formulations within the NiMH chemistry that permit the Panasonic cells to sit at even 0.5V/cell and still be brought back. The Chinese cells completely lack that property. When they go low voltage, it's like a completely discharged 12V battery - they destroy themselves.

You have a 0% chance of success unless you purchase 20 sticks, and unless you buy them from a reputable builder, it's a shot in the dark.

If you're looking for a long term project where you'll learn something, you've found it. Unfortunately, all you will learn is, "wow... that was a monumental waste of time!"

If you don't heed my advice and pursue your plan, I will be the first to say, "I told you so."

 

Update: nothing exploded. P1600 and P1449 intermittently now, when a full assist is used for more than a few seconds (large load), and the other codes are long gone. I didn't really discharge any of them after getting everything revived. Replaced two of the badly burnt cells and one other that was self discharging rapidly.

Kept the CEL off long enough to pass California emissions.
That's a win in my book.

I'm spending a few days driving it on the interstate and I'll probably try a grid charger later this month for fun.

The grid charger DEFINITELY wouldn't have repaired it before, and I'll happily use it on any new pack I purchase eventually (if I have to) so it seems like the next logical investment. Fingers crossed the start clutch is not taking a dump too.

 

Did it take all four months? Congrats. You are an incredibly lucky man. Methinks you should buy some lottery tickets.

Your only defense against a CVT failure is flushing the fluid followed by frequent fluid changes. The DIY flush is 3X Honda fluid changes on 3 consecutive weekends with driving in between. You'll have about 90% new fluid at that point.. If you KNOW it's been changed every 30K miles, then a flush may not be necessary. Change every other oil change after that (about 15K miles. vs .30K per manual). Use only Honda CVT (NOT HCF-2) fluid and not the fluid specified in the owner's manual as the CVT fluid was developed later.

https://www.ebay.com/itm/10-Quarts-P...4383.l4275.c10

 

Well done, 🎉
I just bought a 2007 Honda Civicc Hybrid yesterday and it runs and sounds great even with the IMA / Engine Light + Battery Deterioration error code. The physical labor seems straight-forward enough:
I'd like some more details on:

• what kind of charger did you use to actually test the individual batteries?
• what tools were needed?
• how did you restore the cells? I think I will be replacing thee bad cells vs trying to repair and blow up but curious...
• any recommendations for a vendor for replacement cells? Don't want to go through China/Alibaba and would prefer a company with reviews.

With the price of batteries even refurbished ones being from $1200-$2000 I'd rather make this a personal project as well. The car was only $755 due to the battery issues, and I'd like to say at $1500 all in.

Please PM me if you don't mind sharing some insights..or wic kr app @TheAtlantean

Thanks 🙏