Regenerative brakind disabled, what did they do?
#11
12-20-2008, 07:31 AM
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Join Date: Sep 2006
Location: Beautiful Pacific NW
Posts: 1,678
Re: Regenerative brakind disabled, what did they do?
I'm a little confused as to the "severity" of that statement.
"What does a conventional vehicle do.."
If the conventional vehicle is FWD or F/AWD the transaxle will have been designed to NEVER provide a substantial level of engine compression braking, absent a driver manually downshifting.
Test drive any FWD or F/AWD SUV on the market (possible exception being the RDX w/SH-AWD) and then a BMW X3 or X5 and you will readily note the difference. And then there is the now obsolete FWD Cadillac with the HIGH HP/torque Northstar V8 engine equipped with an over-running clutch in the transaxle to prevent any level of engine compression braking so loss of control is not threatened by engine compression braking.
And take note of how the Sh-AWD system reacts if a high level of engine compression braking is somehow imposed, say a downshift.
But the major difference is that the hybrid systems MUST rely on "simulated engine compression braking", regen, to recharge the hybrid battery, so there is no real "parallel" between conventional and HSD. What would you have the engineers do, say if the SOC charge for the hybrid battery is rapidly approaching "empty", you have been drive on a level roadbed at a constant speed for a hour and now you reach a longish downhill section and "finally" lift the throttle...
HIGH rate of charge, relatively "severe" level of "simulated" engine compression braking, would be the totally appropriate response, right..?
Now put the OAT below 32F as you approach that longish downhill section what would you have the system do...??
Suppose the system DIDN'T "back-off" the charge rate and just by pure happenstance you hit a patch of black ice halfway down that downhill section of roadbed...
The rear of your FEH begins to come around, "pivot", "jack-knifing", around the front "anchor" point, no stearing control since the front roadbed traction co-efficient has now been allocated to "braking", no "leftover" traction at the front for directional control, now what do you do..??
Perhaps, just as the AAA is currently recommending, you have practiced quickly shifting the automatic "transaxle" into neutral for just this situation, you simply follow that practice, shift the FEH into neutral, regain front traction, and drive away.
when its below 35F? Its going to have engine compression occurring every time.
NOT..!!
Does that mean every vehicle out there is a deathtrap once you pull your foot off the accelerator other than a hybrid?
"What does a conventional vehicle do.."
If the conventional vehicle is FWD or F/AWD the transaxle will have been designed to NEVER provide a substantial level of engine compression braking, absent a driver manually downshifting.
Test drive any FWD or F/AWD SUV on the market (possible exception being the RDX w/SH-AWD) and then a BMW X3 or X5 and you will readily note the difference. And then there is the now obsolete FWD Cadillac with the HIGH HP/torque Northstar V8 engine equipped with an over-running clutch in the transaxle to prevent any level of engine compression braking so loss of control is not threatened by engine compression braking.
And take note of how the Sh-AWD system reacts if a high level of engine compression braking is somehow imposed, say a downshift.
But the major difference is that the hybrid systems MUST rely on "simulated engine compression braking", regen, to recharge the hybrid battery, so there is no real "parallel" between conventional and HSD. What would you have the engineers do, say if the SOC charge for the hybrid battery is rapidly approaching "empty", you have been drive on a level roadbed at a constant speed for a hour and now you reach a longish downhill section and "finally" lift the throttle...
HIGH rate of charge, relatively "severe" level of "simulated" engine compression braking, would be the totally appropriate response, right..?
Now put the OAT below 32F as you approach that longish downhill section what would you have the system do...??
Suppose the system DIDN'T "back-off" the charge rate and just by pure happenstance you hit a patch of black ice halfway down that downhill section of roadbed...
The rear of your FEH begins to come around, "pivot", "jack-knifing", around the front "anchor" point, no stearing control since the front roadbed traction co-efficient has now been allocated to "braking", no "leftover" traction at the front for directional control, now what do you do..??
Perhaps, just as the AAA is currently recommending, you have practiced quickly shifting the automatic "transaxle" into neutral for just this situation, you simply follow that practice, shift the FEH into neutral, regain front traction, and drive away.
when its below 35F? Its going to have engine compression occurring every time.
NOT..!!
Does that mean every vehicle out there is a deathtrap once you pull your foot off the accelerator other than a hybrid?
No, only FWD or F/AWD vehicles with automatic transaxles. Assuming they provide a fairly high level of engine compression braking upon throttle lift.
Hint: None do.
Even so, it's best to follow the AAA guidelines, since on a FWD or F/AWD vehicle with an automatic transaxle even the slightest level of engine compression braking can quickly result in loss of control in too many common situations.
Hint
Last edited by wwest; 12-20-2008 at 07:38 AM.
#13
12-21-2008, 09:06 AM
Re: Regenerative brakind disabled, what did they do?
Well, a lot of comments on this one. So, here's what happened in the end.
I left the car plugged in for about two hours then we went out for the evening, a fairly long drive as we picked up a friend (me the designated driver for the evening). Right away I noticed that the battery began to charge quite fast and within about 15 minutes the engine would shut off at traffic lights. The odd thing was it was shutting down outside of any ranges it had before, eg. quite low CHT temp. However, all evening, driving there and home there was no regen braking, nor did any ms come on about that.
The next day, again, vehicle plugged in overnight, off to do some shopping about town and the vehicle was back to normal. That is, regen braking was back and it would only go to EV at what were it's normal ranges, that is CHT seemed to be main limiter.
I did notice at the dealers when I went to get the car it was sitting in the shop with a couple of doors open, I guess that and them working on it and doing whatever, drained the battery. I hadn't realized that could happen.
I left the car plugged in for about two hours then we went out for the evening, a fairly long drive as we picked up a friend (me the designated driver for the evening). Right away I noticed that the battery began to charge quite fast and within about 15 minutes the engine would shut off at traffic lights. The odd thing was it was shutting down outside of any ranges it had before, eg. quite low CHT temp. However, all evening, driving there and home there was no regen braking, nor did any ms come on about that.
The next day, again, vehicle plugged in overnight, off to do some shopping about town and the vehicle was back to normal. That is, regen braking was back and it would only go to EV at what were it's normal ranges, that is CHT seemed to be main limiter.
I did notice at the dealers when I went to get the car it was sitting in the shop with a couple of doors open, I guess that and them working on it and doing whatever, drained the battery. I hadn't realized that could happen.
#14
12-21-2008, 08:52 PM
Re: Regenerative brakind disabled, what did they do?
They set a code.
When I was messing with the shifter, I accidentally got the sensor in a position between P and R.
Obviously it didn't like this, setting a code (check engine AND wrench light), STOP SAFELY NOW message, and killing the ICE (I had it idling for heat).
When I readjusted the sensor and put everything back together, I went to drive it. First drive cycle = Check Engine Light, WRENCH Light, REGEN Disabled, but no STOP SAFELY NOW.
Second drive cycle = Check Engine Light only (no REGEN Disable message, but they still weren't working).
Third drive cycle = Check Engine Light only, with REGEN working just like it should.
Two days later, the Check Engine Light turned itself off.
I never did retrieve the fault code.. didn't have to.
I have a feeling they left something unplugged and had the key on, setting a code. They probably cleared the code, but didn't bother to drive it or anything, so when you picked it up, everything was cleared out and a few drive cycles were necessary for everything to relearn properly.
When I was messing with the shifter, I accidentally got the sensor in a position between P and R.
Obviously it didn't like this, setting a code (check engine AND wrench light), STOP SAFELY NOW message, and killing the ICE (I had it idling for heat).
When I readjusted the sensor and put everything back together, I went to drive it. First drive cycle = Check Engine Light, WRENCH Light, REGEN Disabled, but no STOP SAFELY NOW.
Second drive cycle = Check Engine Light only (no REGEN Disable message, but they still weren't working).
Third drive cycle = Check Engine Light only, with REGEN working just like it should.
Two days later, the Check Engine Light turned itself off.
I never did retrieve the fault code.. didn't have to.
I have a feeling they left something unplugged and had the key on, setting a code. They probably cleared the code, but didn't bother to drive it or anything, so when you picked it up, everything was cleared out and a few drive cycles were necessary for everything to relearn properly.
#15
12-22-2008, 12:12 AM
Ridiculously Active Enthusiast
Join Date: Sep 2006
Location: Beautiful Pacific NW
Posts: 1,678
Re: Regenerative brakind disabled, what did they do?
Well, a lot of comments on this one. So, here's what happened in the end.
I left the car plugged in for about two hours...
Inside a garage...?? A HEATED garage...??
then we went out for the evening,
Hmmm...evening...fairly long drive...COLD evening by chance...??
a fairly long drive as we picked up a friend (me the designated driver for the evening). Right away I noticed that the battery began to charge quite fast
Via the ICE, no regen during this period...??
and within about 15 minutes the engine would shut off at traffic lights. The odd thing was it was shutting down outside of any ranges it had before, eg. quite low CHT temp. However, all evening, driving there and home there was no regen braking, nor did any ms come on about that.
The next day, again, vehicle plugged in overnight, off to do some shopping about town and the vehicle was back to normal. That is, regen braking was back and it would only go to EV at what were it's normal ranges, that is CHT seemed to be main limiter.
Daytime temps are generally higher...
I did notice at the dealers when I went to get the car it was sitting in the shop with a couple of doors open, I guess that and them working on it and doing whatever, drained the battery. I hadn't realized that could happen.
I left the car plugged in for about two hours...
Inside a garage...?? A HEATED garage...??
then we went out for the evening,
Hmmm...evening...fairly long drive...COLD evening by chance...??
a fairly long drive as we picked up a friend (me the designated driver for the evening). Right away I noticed that the battery began to charge quite fast
Via the ICE, no regen during this period...??
and within about 15 minutes the engine would shut off at traffic lights. The odd thing was it was shutting down outside of any ranges it had before, eg. quite low CHT temp. However, all evening, driving there and home there was no regen braking, nor did any ms come on about that.
The next day, again, vehicle plugged in overnight, off to do some shopping about town and the vehicle was back to normal. That is, regen braking was back and it would only go to EV at what were it's normal ranges, that is CHT seemed to be main limiter.
Daytime temps are generally higher...
I did notice at the dealers when I went to get the car it was sitting in the shop with a couple of doors open, I guess that and them working on it and doing whatever, drained the battery. I hadn't realized that could happen.
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