You are on borrowed time… unfortunately.
Not necessarily, if the light originally lit only because the car had been sitting unused for a while.
I've brought back two packs that gave me IMA lights simply because they had been sitting a long time. They just needed to be exercised. The most recent was last week.
To do this, I pulled the power to the BCM when the IMA light came on to reset it. The latest time it only came one once or twice; however, it was frequently background charging and recalibrating. However, after a few hours of driving, this got less frequent, until by the end of a six hour drive I was getting full assist (this was also with a 40% current hack in place.) No grid charger or lightbulb discharger was used.
The first time this happened was when I first got the car years ago; the IMA light came on because it had been sitting after hitting a deer.
The second time was last week when I put a pack in my other car with a bunch of sticks given to me by another owner who pulled them for LiBCM. They had worked in his car but after sitting for a while they lit the IMA light when the car was fired up.
I have noted anecdotally that my IMA batteries seem as strong as ever after returning from a cross-country road trip. I have also had a device in my BCM that reports stick pair voltages to my phone in a bargraph display. It was very obvious that imbalance that was at the start of the drive was gone - a flat line across all ten voltages - at the end of long road trips (many hours). The change was noticeable even after the first hour or so if not sooner.
Bottom line is that I think some people are panicking when they see an IMA light after a long time parked. Sometimes they are right, as I have seen some aftermarket cells not come back after being left idle in a pack for a year, when before they were OK. But if the Honda pack wasn't toasted to begin with (and I do have one of those, a pack from around 2006, which has multiple cells not coming back and split heat shrink visible from outside the pack!), and if it just has been sitting a long, it is a candidate for conditioning, and I will try the "very long drive" method first. However, I make sure that the 12V battery is in good shape and charging (using
@mudder's trick to make the DCDC keep charging the battery like a normal alternator would) and that I don't go further than I want to pay for a tow until I am comfortable that it is improving.
I am wondering if others have observed this phenomenon.
