Symptom of failing battery pack?

Hi folks,

I posted earlier getting failure codes that might indicate something wrong with the battery pack. The codes were P3000, subcode 123, v0100 subcode 211/330. My independent mechanic said that I needed both the battery pack and the battery ECU replaced, based on these codes and the fact that they tested the hybrid pack under load.

At the same time, my auxiliary battery was low. You folks suggested replacing that first.

So I did. I have so far driven over 140 miles without the engine check light and triangle of death coming on again. But I do notice that the SOC screen shows my battery going into the green far more often and far more readily than I remember it doing so in the past. All it takes is a little downhill (say quarter to half a mile) and it will go into green--sometimes 100%.

I'm guess what I'm looking for is some sort of objective data that says my mechanics are right and not shining me on...

Thanks,

Brooke

 

Thanks, JC91006.

I wasn't clear in this message because I was trying to keep it short, but the codes were cleared 140 miles ago. (The check engine light actually turned itself off. I took it to the mechanics anyway, I they read/cleared the codes at that point, which, as I say was 140 miles ago). If I had a bad battery back, is it reasonable to expect that the check engine light would have reappeared by now? Or is it naive of me to think so?

 

No--can't hear it all.

 

Thanks to everyone. This afternoon, I decided to take my car in again and have the battery pack retested.

Previously, when I first encountered the issue and had the codes read, the shop reported that the ECU was bad, that the battery cells were unbalanced, and all cells were weak and dropped fast under load.

Now, after having replaced the 12 volt battery, they are reporting that the ECU appears to be fine and the battery cells are all perfectly balanced. However, under load, the cells drop to the minimum 15 volts and then recharge very rapidly. As I understand it, the battery is technically operating within spec but they believe the battery is beginning to fail based on going down all the way to 15 volts, followed by a rapid recharge. But they also say they've never seen a battery behave quite this way. In their experience, the more common symptom of a failing battery is unbalanced cells.

They recommend that I drive around for a month and then bring it in for another check, free of charge. If I understand it right, the thought is that the oddly rapid recharge they are seeing might be a lingering problem based on the ECU having had problems because of the low 12 volt battery and that it might go away just like the unbalanced cells did.

So their advice and your advice agree--just drive it around and see what happens.

And I'd be happy to do that except for one thing: I am terrified of the thought of going into limp mode while driving a particularly difficult road on my twice-a-week commute. (Four-lane highway over a mountain with curves, steep downhills, semi's, crazed motorcyclists, no shoulders to speak of for stretches--and yet a road that everyone drives at near freeway speeds.)

So given this new data, what would YOU do in this case?

 

Thanks, exstudent. Although I list myself as being in the Bay Area, I'm a good two hours from SF. If I were closer, I'd certainly take your advice.

 

Thanks, JC91006. Good to know that I am not a minimum!

 

Yep, Highway 17 it is.

Thanks for the reassurance, Patrick. As I said, I'm fine with continuing to drive it, particularly if I receive advance warning of traction battery failure. I took the car out for a relatively prolonged spin yesterday. It still has the tendency to go into green after slight downhills, but for the most part it stays in blue on bar 6. And the MPGs I got for the drive seemed normal.

So I will take it over the hill this morning.