I found a particularly interesting and informative post from MSantos on another current thread (sorry, I didn't know how to properly link...):

https://www.greenhybrid.com/discuss/...tml#post179676

#14 (permalink)
07-07-2008, 10:32 PM

Quote:

Indeed, the IPU thermal management is performing as designed.

There are several temperature thresholds within the IPU that are responsible to placing the IMA system into managed mode. Contrary to what some folks say, the IMA is never shutdown. Instead, the managed mode is responsible for canceling thermal escalation, which is an overriding requirement needed to protect the components from damage. Under managed mode the Assist and Regen phases will be curtailed and even canceled as required. Also while in this mode the battery pack can be placed in what is often termed as an instrumented re-initialization mode.

Here are the temperatures to watch for:

MCM - thermal upper limit is 100C (212F)
NiMH battery modules - upper limit is 90C (194F)
DC-DC - upper limit at 215C (419F)

As you can see, any of these threshold temperatures can place place the entire IPU into thermal management mode... so it follows that if you want to avoid the dreaded management mode you should follow the advice we've been giving to HCH-II owners for the better part of the last two years: "Use your AC wisely and you'll do OK. Use it incorrectly or not at all and the result is often unavoidable.

Cheers;

MSantos

 

What is "Auto A/C" vs "regular A/C" ?

Bob, Georgetown, TX
2006 HCH

 

"Auto" simply means engaging automatic climate control (including A/C) via the "Auto" button. The system attempts to maintain a set cabin temp by manipulating the fresh/recirc, the air registers, A/C, and fan speed.

"Regular A/C" can be engaged by pressing the A/C button. In this mode, the system does not work to automatically maintain a certain cabin temp. You still set the air register selection, fresh/recirc, and fan speed.

Steve

 

As in other threads I only get this happening alot when I use A/C for half of my daily commute or just plain use A/C after a few days of not using it before. Lately my office has been turning the A/C way down such that even wearing a long sleeved shirt I'm still cold. Usually I can take this cold air with me almost all the way home and it's been 100+ outside and I've not noticed the battery crashing in over a week (granted my car is in a parking garage at work so it's not hot either).

But if for any reason I have to run an errand over lunch and have to use A/C in this summer then a battery crash is almost guaranteed at the end of the day or the next morning.

 

I've had my 2006 HCH since June 06. This never happened to me until about 2 months ago. I live in Columbia, SC where it gets close to the century mark for a good chunck of the summer. Since it happened 2 months ago I have noticed it nearly a dozen times. At first I thought it was because I had the AC on...though the next time it happened I had the windows down w/out the AC on. So it doesn't appear to be caused by having the AC on though I do not believe having the AC on helps the situation. It also happens upon startup and I've seen it after driving for a few minutes. I've mentioned it to the dealer 4 times (once for this specific reason and three times for other services I had done) though they say it seems to check out just fine.

I think the scary thing was my wife (just today) was driving home from work on the interstate when this happened. She found herself with no battery trying to climb a hill with a 60 mph speed limit and a semitruck flying up on her rear. It isn'
t that serious when you are driving in town though it could be hazardous on the interstate.

 

I have these battery recalibrations about once a week as well. My first year of ownership, I did not have any. My second year, I had just a few.

 

Do you use your a/c John? I've been using mine this week on auto and haven't had it happen--in the last day and a half at least (which isn't saying anything). I am going to have them take a look at the battery when I bring the car in tomorrow and will post back with whatever they find (or more likely DON'T find....).

 

I rarely use AC. Also, the specific times I can remember the recalibration were in the AM. hmmm

 

Yes, I would say that mine happens in the morning 75% of the time. My thinking has been that the battery temperature isn't a factor because of the morning timing, but after reading several pro-A/C posts, I figured it would be worth a try. So far, I haven't noticed much of an FE impact which is a positive thing at least.

 

Not sure if this is good or bad news. We told Honda we weren't going to pick up our car unless they told us what was wrong with it. There was some sort of corrosion on a wire connected to the Thermostat. Honda's explanation was because of the corrosion, the car performed actions as if it was overheating, thus zapping it's battery. If this is the case in my car...I wonder what was causing the corrosion.