Very interesting thread and theory, Steve! I have had this happen 4 or 5 times and they have been very similar each time, but unfortunately I did not think to write it down. It happened yesterday so perhaps these numbers can help:

FEH: 2007 FWD
Lifetime MPG: 37.7
Mileage at recalibration: 41782
Maximum SOC observed: 91.6

I tried yesterday to go as far as possible in EV mode, but once it got out of EV, I could not get it to return until it went under 54% SoC again. One other time I did go a few miles in EV, but probably not quite 6 like gpsman1.

One other nugget of info on this is that I filled up on Saturday morning and it just so happens that I broke my personal best tank with 612 miles and 43.7 mpg. So perhaps there is some indication of the battery recondition being effected by larger than average mpg?

 

Less than a 1/2 mile from home (8:20 PM Eastern Time) , my hybrid battery began its third recaliberation in 39,000+ miles. I drove around slowly in the immediate area and I believe I hit 89.5 for SOC while the TAV on the scanguage rose to 94.3. It was a warm day here and the current temperature is 57 F at 9:05 Eastern. There was no EV allowed while the recalibration was going on. It doesn't take too long for the SOC to return to normal after this event.

 

My 2009 FEH has around 32,000 miles on it and went through its first recalibration that I observed (bought it used). I don't track the lifetime mpg, because when I drive it, it's into the 40s (occasional 50s mpg) but when my wife drives, it's in the thirties. It's starting to get colder here in MO and my mileage has dropped, but when I was going home last night, the FEH just wouldn't drop into EV. I couldn't figure it out then glanced at SOC and was stunned to see it in low 80s. The engine stayed on almost all the way home and the SOC rose to around 95. It was so shocking to me I took a snapshot with my phone when it was at 92.7, then it went into EV the rest of the way home when it was in low 60s when I shut it off. Same ballpark SOC (somewhere in low 60s, not sure it was exactly the same) this morning and continued dropping until I got to work when it was in the high 40s SOC, so it seems to be back to normal. I was really confused until I read this thread.

John

 

You were very perceptive, but yes, this sounds like the usual event.
If driving on the highway at constant speed, you probably would not have noticed. Without a scan-gauge, you for sure would not have known!


I have seen it occur on the highway, on cruise control, at a constant 75 MPH.
Without the Scangauge, it would have been invisible ( which is by design, and good job Ford! )

 

Had my first recalibration today at 34,253 miles while I was standing still for 35 minutes on Interstate (nice timing) due to a crash some ways ahead. The numbers would climb a bit, then the engine would shut off, especially if I was inching ahead, then it would climb again, charging between 12-15 amps.

Saw it go as high as 94.300 on my Dashdaq. Outside temp was 19° and is supposed be below zero most of the weekend. With the snowy, slippery roads and heavy traffic at times, my average speed for the day was quite low (240 miles in 6.5 hours). Only saw 6 cars and 2 trucks in the ditch, but it was dark for 2/3 of the trip.

 

In my Honda, the recals are in your face, and you can witness them on the stock display. They occur more frequently the less the battery is used.
( IE if it is parked for a long time, or I do many days of all highway. )

In the city, when I naturally "exercise" the battery more, I get few, if any recals.

In my 2005 FEH they occur at roughly 10,000 mile intervals.
That may have nothing to do with program, but my driving... nearly all highway these days.

The Hondas have negative and positive recals.

One time in 6 years I've seen my FEH discharge deeply ( to 11% ) while driving. Most of the times ( 5 or 6 I've caught ) it charged to about 90%.

One of those Bills will chime in and say it's just a number and we don't know what the battery state really is.
But we know for sure when it is putting extra kWh in, and taking extra kWh out from time to time.

-John

 

The majority of my miles (1400 a month) is highway. I suspect that will be just the opposite next year and 200 a month will be a lot. At least that's what I predicted when I purchased an extended warranty (7y/75k/$0 ded) last week.

 

I do not agree because in real winter conditions, your hybrid battery will undergo a repeated series of discharges and charges in an attempt to warm itself. Thus those who have to let their car sit in true cold, winter conditions may experience increased battery useage that is unrelated to MPG.

 

True, battery wants to be at least 48° and will charge/discharge until it reaches that, sometimes even at 50°.

It was so cold last week it took me an hour of highway driving to get to 48°.