ICE is not shutting down
#11
09-17-2006, 07:44 PM
Re: ICE is not shutting down
Originally Posted by GaryG
Hi All
The term "engine braking" when the ICE runs up in RPM's, I believe is misunderstood here. As most of you know, my roads are pretty much flat here in So. FL and I didn't experience this situation till I began the use of charging the battery in "L" when reducing speed.
It has always been my opinion that the run up in RPM's was due to the HV battery overheating or is at it's full capacity stopping additional charging. The Traction Battery Control Module (TBCM) and Powertrain Control Module (PCM) determine battery condition, and prevent these conditions.
While there is minor regen still going on as you are going down hill or slowing with the ICE start up and run up in RPM's due to overheat or full battery, the RPM's has nothing to do with the drive axles. The only connection is the energy produced by regen or traction motor that's driving the burn off of that energy with the starter motor (generator) turning the ICE. Many times I reach a complete stop as this burn off occurs.
When I think the battery is full and cannot accept additional charging, I shift to "N" to prevent an ICE restart and run up in RPM's. The Scangauge reads Mast Air Flow as MPG even though the fuel injectors are shut off. This all effects the Navi average and the SG average.
In short, just shift to "N" at this point and use the brake pads to slow down when the battery is overheating or full.
GaryG
The term "engine braking" when the ICE runs up in RPM's, I believe is misunderstood here. As most of you know, my roads are pretty much flat here in So. FL and I didn't experience this situation till I began the use of charging the battery in "L" when reducing speed.
It has always been my opinion that the run up in RPM's was due to the HV battery overheating or is at it's full capacity stopping additional charging. The Traction Battery Control Module (TBCM) and Powertrain Control Module (PCM) determine battery condition, and prevent these conditions.
While there is minor regen still going on as you are going down hill or slowing with the ICE start up and run up in RPM's due to overheat or full battery, the RPM's has nothing to do with the drive axles. The only connection is the energy produced by regen or traction motor that's driving the burn off of that energy with the starter motor (generator) turning the ICE. Many times I reach a complete stop as this burn off occurs.
When I think the battery is full and cannot accept additional charging, I shift to "N" to prevent an ICE restart and run up in RPM's. The Scangauge reads Mast Air Flow as MPG even though the fuel injectors are shut off. This all effects the Navi average and the SG average.
In short, just shift to "N" at this point and use the brake pads to slow down when the battery is overheating or full.
GaryG
Why are you shifting into N? My impression from other threads (and the user manual, if I recall correctly) that the engine breaking is simply used to dump the extra energy generated by the regenerative breaking when the battery is full. What leads you to think it is caused by an overheating battery and something to be avoided? If this were the case, would it not be a design flaw?
The battery is protected by the AC, which is probably why the ICE does not shut down all the time, as the AC needs to run to keep the battery cool.
Thanks for any info.
Roch
#12
09-18-2006, 02:18 PM
Re: ICE is not shutting down
Hi Roch
When the HV battery is full or at a predetermined temp, the Traction Battery Control module (TBCM) sends a signal to the PCM to stop charging from both the small generator and the traction motor/generator (regen). As long as you are slowing down in "D" or "L", the wheels are turning the output shaft and some regen is occurring. You are right, this energy is being disapated (wasted) though the small generator spinning up the ICE. When I place the eCVT into "N" during this time, the output shaft is disconnected from the axles. All regen stops because there is nothing to turn the traction motor as a generator.
Shifting to neutral stops the run up of the ICE preventing unnecessary wear, allows you to go EV much quicker while in "N" and keeps the Scangauge and the FEH MPG readings closer together. We think the Scangauge continues to measure Mass Air Flow for MPG, even though the fuel injectors are shutdown by the PCM. This will cause a lower MPG average reading on the SG which can measure a complete tank MPG average.
When I start out in the morning, my HV battery is about as low as you can get. During this time, I start pumping a charge in the battery with FS's in "L". Within one mile of my cold start, the TBCM senses a hot battery and sends a message to the PCM to stop charging. Remember, a low SoC takes a faster charge and this causes much more heat. This happens every day while its hot here in FL, even with the cabin A/C on. The HV battery is sometimes only half full at this point. As soon as I notice a run up of the ICE, I shift to neutral and tap the brakes to shut down the ICE. With the battery level half full and the CAT warmed up, I begin EV driving. Most of the time, I know when I'm getting close to a run up and shift to "N" to go EV power. After all, I have 29,000 miles of practice.
Those of you letting the ICE spin up on downhills need to shift to "N" and just use the brakes IMO. Your already using most of brake pads at that point anyway. What I try to do is use "L" a little at a time to keep under 40mph in EV or in higher speeds, maintain a safe speed till the battery is full. This allows time for the battery to cool between shifts to "L" if the battery is not already full.
GaryG
When the HV battery is full or at a predetermined temp, the Traction Battery Control module (TBCM) sends a signal to the PCM to stop charging from both the small generator and the traction motor/generator (regen). As long as you are slowing down in "D" or "L", the wheels are turning the output shaft and some regen is occurring. You are right, this energy is being disapated (wasted) though the small generator spinning up the ICE. When I place the eCVT into "N" during this time, the output shaft is disconnected from the axles. All regen stops because there is nothing to turn the traction motor as a generator.
Shifting to neutral stops the run up of the ICE preventing unnecessary wear, allows you to go EV much quicker while in "N" and keeps the Scangauge and the FEH MPG readings closer together. We think the Scangauge continues to measure Mass Air Flow for MPG, even though the fuel injectors are shutdown by the PCM. This will cause a lower MPG average reading on the SG which can measure a complete tank MPG average.
When I start out in the morning, my HV battery is about as low as you can get. During this time, I start pumping a charge in the battery with FS's in "L". Within one mile of my cold start, the TBCM senses a hot battery and sends a message to the PCM to stop charging. Remember, a low SoC takes a faster charge and this causes much more heat. This happens every day while its hot here in FL, even with the cabin A/C on. The HV battery is sometimes only half full at this point. As soon as I notice a run up of the ICE, I shift to neutral and tap the brakes to shut down the ICE. With the battery level half full and the CAT warmed up, I begin EV driving. Most of the time, I know when I'm getting close to a run up and shift to "N" to go EV power. After all, I have 29,000 miles of practice.
Those of you letting the ICE spin up on downhills need to shift to "N" and just use the brakes IMO. Your already using most of brake pads at that point anyway. What I try to do is use "L" a little at a time to keep under 40mph in EV or in higher speeds, maintain a safe speed till the battery is full. This allows time for the battery to cool between shifts to "L" if the battery is not already full.
GaryG
#13
09-18-2006, 05:15 PM
Ridiculously Active Enthusiast
Join Date: Jun 2005
Location: Boston (north suburbs)
Posts: 743
Re: ICE is not shutting down
Originally Posted by GaryG
Those of you letting the ICE spin up on downhills need to shift to "N" and just use the brakes IMO. Your already using most of brake pads at that point anyway. What I try to do is use "L" a little at a time to keep under 40mph in EV or in higher speeds, maintain a safe speed till the battery is full. This allows time for the battery to cool between shifts to "L" if the battery is not already full.
Also, quite often when I am going downgrade and the ICE kicks in, I'm not on the brakes at all so I'll trade a few engine revs for longer brake life.
Now, to go completely opposite the topic, today it seemed like my ICE didn't want to come on. I left the office and headed home, taking my normal route. It was 85° or so and I ran the a/c for 5 minutes or so to cool the interior off. Once I got about half way home, traffic was unusually heavy so we were running around 35-40 mph. The car would go EV and seemed to stay there for great distances. Route 1 where I was is a pretty continuous upgrade headed north (maybe 0.2-0.3%) for 10 miles or so with a couple mild downgrades. I was hitting 42 mph on the speedo and staying there. It was great. My tank average went from 36.8 when I left the office to 39.1 when I got to the house. This was with well over 100 miles on the tank. This was in the '05. Just wanted to share that and didn't think it warranted a new thread.
#14
09-18-2006, 07:03 PM
Re: ICE is not shutting down
Hi Ray
That's why I added "IMO", and it's good that you give your opinion also. As you know, I've stood corrected many times on this and other forums over the past 21 months. Many of the members don't have the SG and have the associated problems I do. My way of thinking has always been, get the ICE off ASAP.
As far as the brake pads, unlike GPSmans1, I do not have much if any wear on the front, and very little on the back because I use "L" too slow down most, no, all of the time thanks to you.
I don't want to brag, but here are my true SG readings "Today" mileage.
47.7 MPG average
24MPH AVG
47mph Max
4.0 Hrs
Max 4180 RPM
97.3 miles
2.0 gal
This was with the normal recir A/C on from a cold start. It got to 92 degrees this afternoon here in WPB.
This was a round trip back to my home where I started cold.
GaryG
That's why I added "IMO", and it's good that you give your opinion also. As you know, I've stood corrected many times on this and other forums over the past 21 months. Many of the members don't have the SG and have the associated problems I do. My way of thinking has always been, get the ICE off ASAP.
As far as the brake pads, unlike GPSmans1, I do not have much if any wear on the front, and very little on the back because I use "L" too slow down most, no, all of the time thanks to you.
I don't want to brag, but here are my true SG readings "Today" mileage.
47.7 MPG average
24MPH AVG
47mph Max
4.0 Hrs
Max 4180 RPM
97.3 miles
2.0 gal
This was with the normal recir A/C on from a cold start. It got to 92 degrees this afternoon here in WPB.
This was a round trip back to my home where I started cold.
GaryG
#15
09-18-2006, 09:30 PM
Hybrid and Ethanol Expert
Join Date: Mar 2005
Location: All over the Central U.S.
Posts: 3,616
Re: ICE is not shutting down
Gary... I think your TYPO Gremlins are at work again.
Pretty sure you meant "like GPSMan1's".
In responce to Ray, I too have noticed one "super charge up" battery condition event, where afterwards, I got 6 miles of continous EV at 0-30 MPH over flat ground, with many stop signs. About twice normal. I noticed the ICE stayed on during stops with the generator charging a totally green battery a few minutes prior.
Pretty sure you meant "like GPSMan1's".
In responce to Ray, I too have noticed one "super charge up" battery condition event, where afterwards, I got 6 miles of continous EV at 0-30 MPH over flat ground, with many stop signs. About twice normal. I noticed the ICE stayed on during stops with the generator charging a totally green battery a few minutes prior.
Originally Posted by GaryG
As far as the brake pads, unlike GPSmans1, I do not have much if any wear on the front, and very little on the back because I use "L" too slow down most, no, all of the time thanks to you.
GaryG
GaryG
#16
09-18-2006, 10:28 PM
Ridiculously Active Enthusiast
Join Date: Jun 2005
Location: Boston (north suburbs)
Posts: 743
Re: ICE is not shutting down
Originally Posted by GaryG
That's why I added "IMO", and it's good that you give your opinion also. As you know, I've stood corrected many times on this and other forums over the past
Maybe I will just edit my signature to reflect that......
#17
09-18-2006, 10:47 PM
Re: ICE is not shutting down
John
Six miles of continuous EV on flat roads without any stops sounds impossible. That is 3 times what I get with no stops using P&G at the best speeds between 20-30mph.
Wish I had a battery like that so I could get 150mpg!
GaryG
Six miles of continuous EV on flat roads without any stops sounds impossible. That is 3 times what I get with no stops using P&G at the best speeds between 20-30mph.
Wish I had a battery like that so I could get 150mpg!
GaryG
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