Functions of Hybrid at Cold Temps.
#31
02-04-2008, 10:07 AM
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Re: Functions of Hybrid at Cold Temps.
But then I thought it fit best into this thread we already had going.
-John
#32
02-04-2008, 05:26 PM
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Re: Functions of Hybrid at Cold Temps.
Low Gear works at all temperatures, and ON ALL ROAD SURFACES.
Tonite on the snowy drive home, I encouraged some wheel slip at slow speed in a parking lot. Then, after, there was no brake pedal regen. Then I shifted to L position and I was getting about 40 amps of regen in "low" with the typical slowing.
So now, to get regen braking when stopping, L gear seems to work all the time ( and the amount you get is based on battery temp. not OAT ).
Tonite on the snowy drive home, I encouraged some wheel slip at slow speed in a parking lot. Then, after, there was no brake pedal regen. Then I shifted to L position and I was getting about 40 amps of regen in "low" with the typical slowing.
So now, to get regen braking when stopping, L gear seems to work all the time ( and the amount you get is based on battery temp. not OAT ).
#33
02-04-2008, 05:44 PM
Re: Functions of Hybrid at Cold Temps.
Low Gear works at all temperatures, and ON ALL ROAD SURFACES.
Tonite on the snowy drive home, I encouraged some wheel slip at slow speed in a parking lot. Then, after, there was no brake pedal regen. Then I shifted to L position and I was getting about 40 amps of regen in "low" with the typical slowing.
So now, to get regen braking when stopping, L gear seems to work all the time ( and the amount you get is based on battery temp. not OAT ).
Tonite on the snowy drive home, I encouraged some wheel slip at slow speed in a parking lot. Then, after, there was no brake pedal regen. Then I shifted to L position and I was getting about 40 amps of regen in "low" with the typical slowing.
So now, to get regen braking when stopping, L gear seems to work all the time ( and the amount you get is based on battery temp. not OAT ).
While pulling in driveway, SoC was 40.x %, so ICE was ready to start. Wanted to wash it, so put it in Neutral with emergency brake on, turned on the Radio to increase current draw, and while washing the car, kept glancing through the window at SoC on SGII-xg. Sure enough, SoC dropped below 40%, down to eventually about 37.x%, and ICE never started. To further prove the point, I was unable to start it with gearshift in Neutral.
So in the future, if I'm sitting at a long traffic light and SoC is about to drop to 40% and/or the CHT is about to signal the ICE on, I'll just shift to 'N' to keep the car from starting until the light changes to 'Green'.
Even though I'd read that the FEH could not start in neutral, I didn't prove it to myself until yesterday. I know I'll never be smarter than a 5th grader, but if I keep on, I may graduate to 2nd grade science
#34
02-04-2008, 08:26 PM
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Re: Functions of Hybrid at Cold Temps.
So in the future, if I'm sitting at a long traffic light and SoC is about to drop to 40% and/or the CHT is about to signal the ICE on, I'll just shift to 'N' to keep the car from starting until the light changes to 'Green'.
Even though I'd read that the FEH could not start in neutral, I didn't prove it to myself until yesterday.
Even though I'd read that the FEH could not start in neutral, I didn't prove it to myself until yesterday.
'Neutral' only disconnects electrical power from the motors, but there are several other threads dedicated to this topic... so I almost didn't want to bring it up here.... ( not related to Hybrid at Cold Temps. ) sorry.
-John
#35
02-05-2008, 10:56 AM
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Re: Functions of Hybrid at Cold Temps.
I still do not have this car figured out.
This A.M. there was lots of black ice as a result of 32 degree snow yesterday, and 15 degree temperatures today.
Slowing from 35MPH to 30MPH I had regen. Then my wheels skid, and I had an ABS event from 30 MPH to say, 25 MPH. Then I hit pavement again, and regen came back on for 25 MPH down to a crawl.
All within seconds, and All without removing my foot from the brake pedal.
This A.M. there was lots of black ice as a result of 32 degree snow yesterday, and 15 degree temperatures today.
Slowing from 35MPH to 30MPH I had regen. Then my wheels skid, and I had an ABS event from 30 MPH to say, 25 MPH. Then I hit pavement again, and regen came back on for 25 MPH down to a crawl.
All within seconds, and All without removing my foot from the brake pedal.
#36
02-07-2008, 10:25 AM
Re: Functions of Hybrid at Cold Temps.
If I weren’t so inquisitive, I'd be tempted to raise the white surrender flag in front of the FEH, and admit that I’ll never figure out how it’s computer brain works.
I have experienced the following regarding cold weather behavior, but not related to ABS event. OAT is well below freezing, and garage is ~50F. IAT on SGII, Inst panel display, and Tav have all equalized to ambient, and measure around ~50F. Immediately out of the garage you have Regen when touching the brakes. Half-mile down the road, Tav is still the same, but IAT now below freezing, and NO Regen at stop sign. Drive slowly another half-mile, another stop sign, and Regen returns to normal and stays that way regardless of OAT. Regen inhibited only one time during this temp swing scenario. It’s repeatable.
Does the software look at IAT/OAT the 1st time, compare that with CHT or something else, and determine that battery can’t possibly be warm enough to accept Regen w/o checking bat temp? And then the second time, it checks the bat temp, and decides that it can accept Regen regardless of IAT/OAT? Beats me??
A few days ago, we had 68F weather, and behavior is very predictable compared to cold weather
I have experienced the following regarding cold weather behavior, but not related to ABS event. OAT is well below freezing, and garage is ~50F. IAT on SGII, Inst panel display, and Tav have all equalized to ambient, and measure around ~50F. Immediately out of the garage you have Regen when touching the brakes. Half-mile down the road, Tav is still the same, but IAT now below freezing, and NO Regen at stop sign. Drive slowly another half-mile, another stop sign, and Regen returns to normal and stays that way regardless of OAT. Regen inhibited only one time during this temp swing scenario. It’s repeatable.
Does the software look at IAT/OAT the 1st time, compare that with CHT or something else, and determine that battery can’t possibly be warm enough to accept Regen w/o checking bat temp? And then the second time, it checks the bat temp, and decides that it can accept Regen regardless of IAT/OAT? Beats me??
A few days ago, we had 68F weather, and behavior is very predictable compared to cold weather
#37
02-07-2008, 09:37 PM
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Re: Functions of Hybrid at Cold Temps.
[quote=gpsman1;160736]
After extensive observations, my REGEN behaves normally, or nearly normal at very cold, even sub-zero temperatures. I do not think there is a program to cut-off regen simply because it is cold.
I think the car is smart enough to actually detect the slightest amount of wheel slip... THEN eliminate regen.
I've been driving sub-zero for a month, and roads have been clear and dry.
I have had regen at every brake pedal press.
I would guess that if regen capability is being lowered below ~34F it would only be during non-braking coastdowns. The idea is to prevent you from losing directional control upon unexpectedly/inadvertently encountering a patch of ice, BLACK ice.
When you are appying braking in those conditions you would, or should, be fully aware of the potential outcome so no harm no fowl if regen is used, fully used, along with actual braking.
Today it was 31-32 degrees with heavy snow. My HV battery was 60 degrees from the plug-in heater, and I had no regen during braking. The car still went EV quickly, and I took off to 25-30 miles per hour in EV, but there was no regen at several stops. This car is so smart, it is a little scary. Either it detected the slightest amount of wheel slip ( I am a slow driver, and I personally didn't detect any slip or skid at all... ) or it has a wireless link to the National Weather Service.
"Either it detected the slightest amount of wheel slip..."
Well, yes.
A second aspect, technique of the patent is to disable regen the very instant ABS activates during actual braking. I suspect that is so that regen does not interfere with ABS' ability to keep the front tires rotating even ever so slightly.
Perhaps there is an event counter / event timer.
Perhaps after a wheel slip event... it says... okay, for the next XXX seconds there will be no regen until I see things improve.
Perhaps AFTER xxx seconds of no wheel slip, regen is turned back on?
Perhaps this A.M. I had a little wheel slip every couple minutes, so the timer never got zeroed out, and regen never came back on?
Perhaps in my several weeks of sub-zero I didn't have ANY wheel slip detected, so the car infered it was OK to use regen?
Sounds very likely to be the case from what I have observed.
-John
After extensive observations, my REGEN behaves normally, or nearly normal at very cold, even sub-zero temperatures. I do not think there is a program to cut-off regen simply because it is cold.
I think the car is smart enough to actually detect the slightest amount of wheel slip... THEN eliminate regen.
I've been driving sub-zero for a month, and roads have been clear and dry.
I have had regen at every brake pedal press.
I would guess that if regen capability is being lowered below ~34F it would only be during non-braking coastdowns. The idea is to prevent you from losing directional control upon unexpectedly/inadvertently encountering a patch of ice, BLACK ice.
When you are appying braking in those conditions you would, or should, be fully aware of the potential outcome so no harm no fowl if regen is used, fully used, along with actual braking.
Today it was 31-32 degrees with heavy snow. My HV battery was 60 degrees from the plug-in heater, and I had no regen during braking. The car still went EV quickly, and I took off to 25-30 miles per hour in EV, but there was no regen at several stops. This car is so smart, it is a little scary. Either it detected the slightest amount of wheel slip ( I am a slow driver, and I personally didn't detect any slip or skid at all... ) or it has a wireless link to the National Weather Service.
"Either it detected the slightest amount of wheel slip..."
Well, yes.
A second aspect, technique of the patent is to disable regen the very instant ABS activates during actual braking. I suspect that is so that regen does not interfere with ABS' ability to keep the front tires rotating even ever so slightly.
Perhaps there is an event counter / event timer.
Perhaps after a wheel slip event... it says... okay, for the next XXX seconds there will be no regen until I see things improve.
Perhaps AFTER xxx seconds of no wheel slip, regen is turned back on?
Perhaps this A.M. I had a little wheel slip every couple minutes, so the timer never got zeroed out, and regen never came back on?
Perhaps in my several weeks of sub-zero I didn't have ANY wheel slip detected, so the car infered it was OK to use regen?
Sounds very likely to be the case from what I have observed.
-John
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