I was doing some freeway driving yesterday, and both myself and my wife noticed that when we went down hill (presumably the battery was pretty fully charged, since we had been moving at 60 MPH for 1/2 hour), there was a very faint high pitched whine, apparently from the front of the car. As soon as the engine picked up a load, the whine disappeared. It is very consistent.

Am I correct in assuming that this is the generator motor, bleeding off excess energy?

 

This whine is characteristic of Escape Hybrids. My understanding is that it comes from the CVT (transmission) and that it is reduced or completely absent in the 2009 models.

 

Hmmm, difficult to believe; the eCVT is unchanged for 2009.

 

I use this slight whine to let me know when I'm doing a good job at DWL on the interstate. At my highway speeds the whine accompanies good FE numbers.

 

I concur, but I'm interested in exactly what is causing it.

 

With NVH (Noise, Vibration and Harshness) being a key point for Ford on this vehicle, I can see where they might have done something in the 09 model to fix it.

I guess we'll add that to list of questions for whoever gets that lucky first drive...

 

Yes that is the "gas mileage going up" indicator After a couple of days on my first long trip with the 08 I stopped worrying about it and looked forward to hearing it... now where is GaryG or GPsman to give us the scientific explanation?

 

Definately the "gas mileage going up" indicator. I notice it most on the interstate when I am going downhill. The nav screen will show a thicker dotted line from from the EM to the axle, while the ICE only has a very thin dotted line showing (and sometimes if I am LUCKY no line, ICE is on but idle only EM providing power). Also I've noticed it is when the the Instant MPG gauge is pegging at 40+.

I'm sure it has something to do w/the EM providing most or all the power vs the ICE or being balanced. At least that is what it seems to me.

It was slightly annoying at first, but now I look forward to it because my avg mpg is going up, during those time periods.

 

Without being there, it is likely the normal sounds of the electric motor or generator working in generator mode... since most of you hear it when coasting slowing down.

There is not any "bleeding off" ( IE waste ) unless your dash RPM shows 3500 to 4000 RPM.

The battery can take more regen charge even when your dash icon looks "full".
It just does not prefer to charge when the icon shows full, and it charges more gently when the icon is full.

I have never ever had my battery too full for regen.
The regen will take a break to avoid heating the battery when you go down a long hill.
But I've never had it totally disabled, so I think it is a myth.
I descended the Rocky Mountains a few times from 12,000 feet to 5,000 feet over about 25 miles. With a ScanGauge, I was getting regen ( at a slow pace ) with my battery at 78% full. The regen never turned off for more than a few seconds at a time to limit battery heating. I ran out of downslope at 78% SOC. I wish I had a longer hill!!!

Your HV battery pack is normally in the 40% to 53% range. That leaves a lot of room for regen. You get a totally "full" icon on the screen at just 58%. Thus, if you hear a whine even with a full icon, you are probably still charging, just at a slower pace than full regen.

-John

 

I also think the whine is at a pitch that some people might be more sensitive to than others.

Like I said, I'm not complaining. If I don't want to hear it I can easily turn on the radio or crack a window.