Mountain Driving Help

[ScubaDadMiami]

even just spinning the engine at high speed does still subject all the parts to the same or similar forces as when when it is actually running.  I will admit that the Ford engineers probably decided that 4,000 or 4,500 RPM is not an unsafe speed, or they would not have programmed the car to permit that, but I like to keep my cars for >10 years/100K miles, so I try not to always push the car to the limit...sometimes, you can't help it, but I try to avoid beating on the car on a daily basis.

I don't live in the mountains, but I've traveled there in my C-MAX. I know that it sounds scary when you hear ICE turning without firing, but I just don't sweat it. When I was just in New England, I ran down 15 percent grades with Downhill Assist on and a maxed out HVB. All I could think was: "What a waste of regen!" After all, once the HVB is fully topped off, the rest just goes bye-bye.

 

Honestly, I wouldn't worry about it. It has to be softer on the engine to turn without the heat from the combustion happening than it is with running ICE, even if everything is turning at a high rate of speed. My guess would be that lubrication is provided to the cylinder walls, or that enough is already there, to allow extended high RPM.

[ptjones]

Looking at the Smart Gauge Tack It looks like 6,000rpms is the red line for the ICE, no reason to sweat 4,500. BTW the ICE still makes some heat from compressing air in the cylinders so the ICE doesn't cool off totally going down hill. You wouldn't want to waist gas heating up the ICE again. :) 

 

Paul 

[stevedebi]

I think you are correct...there may be some small difference between acceleration and deceleration (or I suppose more properly, negative acceleration), but even just spinning the engine at high speed does still subject all the parts to the same or similar forces as when when it is actually running.  I will admit that the Ford engineers probably decided that 4,000 or 4,500 RPM is not an unsafe speed, or they would not have programmed the car to permit that, but I like to keep my cars for >10 years/100K miles, so I try not to always push the car to the limit...sometimes, you can't help it, but I try to avoid beating on the car on a daily basis.

I had an Escape Hybrid, and on a trip to New Mexico, on secondary roads with a lot of uphill / downhill (about 200 foot hills), I saw the RPM go up past 6000 on the uphills. I didn't sweat it, since Ford designed the computer parameters to protect the engine as needed. I don't really worry about it myself. On my Energi, I don't usually even have the RPM guage up on the left hand MyView.

 

I also hope to have mine well past 100K.

[stevedebi]

...

 

I don't recall anyone who has documented / described the hybrid mode operation in the Energi.  I would think the hybrid mode algorithms are the same except perhaps threshold levels in the Energi might be increased  - but why? running ICE just to charge the big HVB (in positive split mode) even now with low gas prices would likely cost (in Phoenix with about $2.64 / gallon) over twice as much to charge the HVB with gas vs electricity.   But when descending a hill in the Energi, it makes sense to maximize regeneration whether the car in in D or L.   So, ICE should not spin in L to slow the car down like in the Hybrid. 

A bit off topic, so for those who don't care about the Energi - just skip this!

 

From what I can tell, the Energi uses the same (fairly small) range of battery that the conventional C-Max uses, when it is in what I call "highway mode", which means the larger part of the battery is depeleted, or the owner has set EV Later (which reserves the larger battery for later off highway use). I think Ford just copied the algorithms between the two. It makes sense, as you note, because there is no point in charging the HVB past a certain point - it is just burning gas.

 

The only difference I can tell is that the Energi will often not spin up the engine in L, because it has more capacity to store energy, and that it can recover extra energy on large downhill slopes, which it then burns off in either EV or just assisting the engine. After any excess is used, it reverts to that same highway mode.

 

I follow this forum because there is a lot of stuff the same between the two models. I try to think twice before posting, to make sure my Energi doesn't operate differently than the C-Max. I don't want to waste people's time reading stuff that doesn't apply.

[fbov]

When possible I try to use up the HVB before I get to the top of a hill so I can get the maximum of regen braking and use down hill assist If I need to....

My technique is the opposite:

When possible I try to charge up the HVB before I get to the top of a hill so I can get the maximum glide range on the way down.

 

I know... spoken like a true flat-lander. I can accelerate up most hills with less than 2-bar throttle, so I'm still charging. You may not, and it may be one reason your mileage eclipses mine.

 

Regarding fuel-off engine RPM, consider that, without fuel, the engine's using pumping losses to dissipate energy, and not experiencing a power stroke, so internal stresses are much, much less than if you were running under load at that RPM. It just sounds terrible compared with the relative silence of normal operation. 

 

HAve fun,

Frank

[bigqueue]

On 8/10/2013 at 8:58 AM, fotomoto said:

Brake light is NOT on during regen nor is it required to be. 

 

 

As a motorcycle rider, I can tell you how important it is to show brake lights when you are slowing because some people snooze at the wheel and don't realize the vehicle in front of them is getting closer. Granted, it is far more important on a motorcycle since there is not simple "fender bender" when being rear-ended. So on motorcycles there are circuits you can add to your tail lights that use accelerometer to enable your brake light whenever the motorcycle is decelerating. (warning / signalling the drivers behind you)

 

-Quentin