A strange thing happened this morning on my way to work. I was proceeding down my steep 9% grade hill with cold engine on my '06 HCHII. I looked down and saw that the instant MPG gauge was low (maybe one or two bars!). I was on the brakes (going down hill) so this didn't make sense. In addition, there were absolutely NO green bars on regen charge. The battery SOC meter showed almost full, so I guess it's understandable why there was no charging going on. Just don't know why MPG was so low.

This condition happened for the full two minutes I decended the hill. At the bottom, things seemed normal again. Still too cold for AutoStop, but everything else was fine.

Any idea why this happened?

 

A similar thing happened to me this monring and it was chilly in Phoenix so I just figured that was the reason because of posts that I have read hear regarding the effeects that temperature has.

 

Temperature was maybe mid 50's here, so not really chilly (at least by early spring standards for much of the country!). It's been cooler on other mornings where it didn't do it.. or at least I didn't notice!

At least I know I'm not the only one this has happened to.

 

I live in Gilbert. I don't think chilly has happened here in quite a while. Should be in the 100's next week - its going to be a loooong HOT summer for us.

 

I've also seen erratic behavior of the IFG sometimes. It will show very low mileage when it doesn't seem to make sense. It also bounces up and down sometimes for no apparent reason, when the engine is cold.

When the engine is cold it revs up on automatic choke, consuming a lot of fuel and not activating the valve shutoff when gliding. Still, I don't think that explains the occasional erratic behavior.

 

I have been told by my honda dealer that it is a automatic recalibration that is happening when this happens.., nothing abnomral .

 

I see this behavior every morning on my way down the hill. The trip A mileage calculation continues to go up even while the the IFG shows only a couple of bars.

 

I suppose is all depends on what chilly is to you. I left the house at about 5 AM and it was in the 50's and being that I am a native (and a wimp), it was a bit chilly for me.

 

Today's update... identical trip, same temperature (mid 50's):

Today, the IFG worked fine. There was still no regen charging, though. Once I got on the freeway, I noticed something else... under normal cruising (58mph) on a slight upgrade, IFG was lower than normal, perhaps 30mpg. At that time, there were three green charge bars. Suddenly, the charge bars went away and MPG returned to around 50. I'm suspecting that the battery needed to be charged, and this created an engine load which reduced MPG.

The question I have... why did the battery recharge via engine load instead of the FREE regen that was available to it just 3 minutes earlier (braking coming down the big hill)? I'm guessing it's because the system didn't want to charge the battery when it was "cold"... but in fact, I'd bet the core temperature of the battery was no different (3 minutes later). Seems wasteful to me... and if it happens every day, it's VERY wasteful.

 

Its my understanding of batteries in general that they are rather sensitive to temperature as far as charging rate, capacity, and power delivery as well. We went over that in Physics class. Furthermore, the HCH is even MORE sensitive to battery temp and SoC in order to maximize battery life. So even though the battery may not seem like it changes much over a couple of minutes, it does, and the regen will respond accordingly.

The fluctuation of the IFG IS a calibration. Its in the manual somewhere. It just happens kinda often, which I find weird. Makes me think its a bug sometimes, but I'm sure its just that: a calibration.