Spontaneously aborted S4 glides at 26 MPH

JimboK · 08-08-2007, 07:07 PM

We had a record temperature today: 104F. In fact, that's the hottest it's been in these parts since July, 1977. I began my afternoon commute in the usual hot weather manner: driving the first mile or so without AC until I could more or less sustain my drive, at which point the car was in S4. Can-View showed battery temperature at 100F on startup, up to 102F when the AC (auto mode set to 80F) went on, and then up to 105F where it remained despite continuous AC. SOC hovered around 50% as I did my usual P&G, with pulses up to between 28 to 35 MPH, depending on traffic.

Here's the curious thing: On several pulses in the first half of the commute, the glide spontaneously aborted and the ICE lit, each time at 26 MPH. Since SOC was adequate to allow a glide, my first thought was, "hot battery." But then later in the commute the issue resolved despite battery temperature remaining at 105F.

The car seemed sluggish throughout the drive, which I again attributed to the hot battery. Nothing else was amiss with other Can-View readings.

As some of you have reported, I've had the car (very infrequently) refuse to begin an S4 glide, but I haven't experienced or read about it aborting one spontaneously like this part-way through. It seemed especially odd that it happened precisely at 26 MPH each time.

Anyone ever seen this?

Green Hokie · 08-08-2007, 09:10 PM

Good evening, Jim!

Yes. It was sure was a scorcher out there today in that +104 F heat! I'm afraid I don't have any insight into your particular experience. However, here's what I observed over the last two days, which may lead you to some ideas.

I actually drove home from work this afternoon (at 5pm) with no AC and all windows down. Yeah, call me crazy. But you know what, it wasn't bad at all. Guess I'm pretty tolerant to extreme heat. My Prius had been parked in the sun all day (since 8am) and usually gets a little bit of shade (for about 1/2 hr) before I leave work. Anyway, I have no idea what the battery temp was during my drive home (don't have a scangauge or can-view, yet). However, at no point did I have any trouble gliding and my battery was charging as normal (got up to 6 bars a few times during the drive home). My mpg average actually climbed to 72.6 by the time I got home. For the most part, my speed varied from 25-41 mph. Yes, I've found an alternate route for my daily work commute, which has essentially eliminated any interstate driving.

Now, let's compare this to yesterday when the air temp in our area was "only" around 97 F. That day, I drove home with the AC on (lowest fan speed at lowest temp setting). During the entire drive, I had difficultly gliding and also could not get a decent charge on the battery (highest I saw was 4 bars). By the time I got home, my mpg had dropped from 71.6 to 68.9. Exact same route and pretty much the same speeds as today.

Here's my theory. This afternoon, even with the +104 F heat, I got more & stronger air flow to the vents in the rear seats (which lead to the battery pack) by having all the windows down. The better air flow (even if it's hotter air) actually did a better job of cooling the battery pack than running the AC at the lowest fan speed (in recirc mode) with very little air flow those rear battery vents.

What do you think? Does this theory make any logical sense to you?

patsparks · 08-09-2007, 02:06 AM

I wonder if having just the right rear window down would do the same thing? The wind would be right on the vent for the battery wouldn't it? This may force air through the battery better than the fan?

JimboK · 08-09-2007, 07:34 AM

<div class='quotetop'>QUOTE(Green Hokie @ Aug 8 2007, 09:10 PM) [snapback]492746[/snapback]</div>

Quote:

What do you think? Does this theory make any logical sense to you? [/b]

Hey, Peter. Great numbers you're getting there!

It makes sense at face value. And what patsparks suggests would seem logical too. Maybe I'll try it today and tomorrow and watch the battery temperature ... if I can stand it. I'm not very tolerant of the heat!

Many here have said that if the driver is uncomfortably warm, the battery is too, and AC should be run to keep the battery happy. It didn't seem to matter yesterday. Maybe it was that first few minutes without it, though I saw a slightly greater rise in battery temp after turning the AC on. Maybe I didn't have the AC set cool enough. Maybe you guys are onto something with the air flow theory. Or maybe it was just the extreme heat.

Off topic and mainly of local interest, you might be interested in this.

FireEngineer · 08-09-2007, 09:41 AM

The Cal-cars people have seen that at about 104F the Prius really protects the battery, especially if your SOC is below 6 bars. The battery fan doesn't kick in until about 120F. AC draws from the HV battery quite a bit, increasing ohmic heating inside the modules. The Prius was trying to protect the battery by running the ICE to run MG1 to provide the power to the AC and limit current in/out of the battery. I believe Doug Schaefer saw the battery temp go down 1F every 5 minutes of AC use, remember it has to be flow through, not recirc. Think Pete has the right, though uncomfortable, idea on how to drive.

My personal style is to open both front windows trying to create a high pressure area in the back seat which would vent through the battery vent. Really depends on your route, the outside conditions and what you can stand. When we had 97F going home the other day, I tried to keep the acceleration between 1200-1500RPM to limit ICE comsumption, keep under hood cool and limit MG1 current into the battery. Never had a unwanted ICE run and my ICE temp reached no higher than 194F, with an almost full grill block. SOC was almost always at 6 bars.

Wayne

David Beale · 08-09-2007, 11:46 AM

Also remember the battery is a large block of metal, and it takes a long time to heat it up and a long time to cool it off once it's heated up. It isn't going to change temperature rapidly. It started at 100 F (ambient - and had all day to get there). You started using the battery, so it heated up a little more, but even if you blew 70 F air on it with a large fan it wouldn't cool off for at least an hour. The tiny fan the Prius uses is going to take a while to cool the battery. But at least it held the temp at 105 F while the car was using the battery.

We don't get those kinds of temps. here, but one day we were at +30 C and I noticed a lower SOC, poorer mileage, and more ICE operation. Yes, I had A/C on - set to 27 C - even 30 C is too hot for me!

Oh, and the Scangauge will not indicate traction battery temp or any other parameters. Those are "CAN" messages. The Scangauge only sees standard ODBII messages, such as coolant temp, 12V battery voltage, fuel use, etc.

Green Hokie · 08-09-2007, 01:17 PM

<div class='quotetop'>QUOTE(JimboK @ Aug 9 2007, 07:34 AM) [snapback]492909[/snapback]</div>

Quote:

Off topic and mainly of local interest, you might be interested in this.
[/b]

Nice! I'll keep an eye out for that broadcast. If you do find out, please let me know exactly when the local NBC station will air that story.
I'll have to get your autograph the next time I see you

(Prius meet in the fall?)

<div class='quotetop'>QUOTE(David Beale @ Aug 9 2007, 11:46 AM) [snapback]492992[/snapback]</div>

Quote:

Oh, and the Scangauge will not indicate traction battery temp or any other parameters. Those are "CAN" messages. The Scangauge only sees standard ODBII messages, such as coolant temp, 12V battery voltage, fuel use, etc.
[/b]

David, According to one of the techs I spoke to recently at scangauge, the ScanGauge II will soon have the ability to display battery temp as well as other additional readings (like CAN-view). Apparently, this will be possible via a firmware update. Feel free to contact scangauge to learn more.

Cheap! · 08-09-2007, 01:49 PM

I use a “Fan Mod” on my fan to get it to go full bore when the OEM battery temperature gets above 94 deg. I want to modify it further to run as normal and then at my will, push a button to force it to full bore. The fan itself makes no noise, but the sucking air sound through the plenum is loud enough to be annoying if the radio is not on.

Also, I have been looking into a direct tap modification to the AC/Heat vent to get the air into the battery compartment without mixing with the ambient passenger compartment air.

I believe the Toyota guys should look into improving battery temperature management for the next Prius. Right now in Houston, the passenger compartment can reach 130 degrees and why would you want to grab that air. On the other hand out side temperatures are reaching 100 deg F. here. They need a system that would grab air from the best possible place depending on the batteries needs, whether it be from the inside, outside, or if it has to start up the AC/Heater, on it's own and grab the air from there. That system would be fairly complex (no more so then the regular AC vent system) but I think it would be helpful in there plug in version if it ever makes it to market.

FireEngineer · 08-09-2007, 02:37 PM

<div class='quotetop'>QUOTE(Cheap! @ Aug 9 2007, 12:49 PM) [snapback]493089[/snapback]</div>

Quote:

They need a system that would grab air from the best possible place depending on the batteries needs, whether it be from the inside, outside, or if it has to start up the AC/Heater, on it's own and grab the air from there. That system would be fairly complex (no more so then the regular AC vent system) but I think it would be helpful in there plug in version if it ever makes it to market.
[/b]

Ford Escape Hybrid has those features.

Wayne

Green Hokie · 08-09-2007, 04:15 PM

That's it! I'm trading in my Prius for an Escape Hybrid.

Just kidding, of course!

08-08-2007, 07:07 PM	#1
JimboK One owner, low mileage Join Date: May 2006 Location: Chesterfield, VA Posts: 1,886 My Car: 2005 Prius Package: #2 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 2	We had a record temperature today: 104F. In fact, that's the hottest it's been in these parts since July, 1977. I began my afternoon commute in the usual hot weather manner: driving the first mile or so without AC until I could more or less sustain my drive, at which point the car was in S4. Can-View showed battery temperature at 100F on startup, up to 102F when the AC (auto mode set to 80F) went on, and then up to 105F where it remained despite continuous AC. SOC hovered around 50% as I did my usual P&G, with pulses up to between 28 to 35 MPH, depending on traffic. Here's the curious thing: On several pulses in the first half of the commute, the glide spontaneously aborted and the ICE lit, each time at 26 MPH. Since SOC was adequate to allow a glide, my first thought was, "hot battery." But then later in the commute the issue resolved despite battery temperature remaining at 105F. The car seemed sluggish throughout the drive, which I again attributed to the hot battery. Nothing else was amiss with other Can-View readings. As some of you have reported, I've had the car (very infrequently) refuse to begin an S4 glide, but I haven't experienced or read about it aborting one spontaneously like this part-way through. It seemed especially odd that it happened precisely at 26 MPH each time. Anyone ever seen this? __________________ Jim Lifetime fuel mileage: After learning how to hypermile: Click here for car details.

08-08-2007, 09:10 PM	#2
Green Hokie Senior Member Join Date: Mar 2007 Location: Glen Allen, VA Posts: 169 My Car: 2007 Prius Package: S Touring Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Good evening, Jim! Yes. It was sure was a scorcher out there today in that +104 F heat! I'm afraid I don't have any insight into your particular experience. However, here's what I observed over the last two days, which may lead you to some ideas. I actually drove home from work this afternoon (at 5pm) with no AC and all windows down. Yeah, call me crazy. But you know what, it wasn't bad at all. Guess I'm pretty tolerant to extreme heat. My Prius had been parked in the sun all day (since 8am) and usually gets a little bit of shade (for about 1/2 hr) before I leave work. Anyway, I have no idea what the battery temp was during my drive home (don't have a scangauge or can-view, yet). However, at no point did I have any trouble gliding and my battery was charging as normal (got up to 6 bars a few times during the drive home). My mpg average actually climbed to 72.6 by the time I got home. For the most part, my speed varied from 25-41 mph. Yes, I've found an alternate route for my daily work commute, which has essentially eliminated any interstate driving. Now, let's compare this to yesterday when the air temp in our area was "only" around 97 F. That day, I drove home with the AC on (lowest fan speed at lowest temp setting). During the entire drive, I had difficultly gliding and also could not get a decent charge on the battery (highest I saw was 4 bars). By the time I got home, my mpg had dropped from 71.6 to 68.9. Exact same route and pretty much the same speeds as today. Here's my theory. This afternoon, even with the +104 F heat, I got more & stronger air flow to the vents in the rear seats (which lead to the battery pack) by having all the windows down. The better air flow (even if it's hotter air) actually did a better job of cooling the battery pack than running the AC at the lowest fan speed (in recirc mode) with very little air flow those rear battery vents. What do you think? Does this theory make any logical sense to you? __________________ Pete 2007 Touring Pkg 3, Magnetic Gray Metallic 3M Ultrashield clear film on hood, front fenders, front bumper, side mirrors, headlights, foglights and top of rear bumper Covercraft UVS100 sunshield OEM EV switch ScanGauge II Engine Block Heater Blocked Grill (upper & lower) Mud Guards Tire Pressure: 44/42 psi

08-09-2007, 09:41 AM	#5
FireEngineer Senior Member Join Date: Oct 2004 Location: SW-Side of Chicago, IL Posts: 752 My Car: 2005 Prius Package: #6 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 3	The Cal-cars people have seen that at about 104F the Prius really protects the battery, especially if your SOC is below 6 bars. The battery fan doesn't kick in until about 120F. AC draws from the HV battery quite a bit, increasing ohmic heating inside the modules. The Prius was trying to protect the battery by running the ICE to run MG1 to provide the power to the AC and limit current in/out of the battery. I believe Doug Schaefer saw the battery temp go down 1F every 5 minutes of AC use, remember it has to be flow through, not recirc. Think Pete has the right, though uncomfortable, idea on how to drive. My personal style is to open both front windows trying to create a high pressure area in the back seat which would vent through the battery vent. Really depends on your route, the outside conditions and what you can stand. When we had 97F going home the other day, I tried to keep the acceleration between 1200-1500RPM to limit ICE comsumption, keep under hood cool and limit MG1 current into the battery. Never had a unwanted ICE run and my ICE temp reached no higher than 194F, with an almost full grill block. SOC was almost always at 6 bars. Wayne __________________ 2005 Salsa Red Package 6 (BC) 2004 Oldsmobile Silhouette "Final 500" mini-van Free engine block heater install, just ask. 110 warmer Prius done to date. Come join us at the ChicagoPriusGroup.

08-09-2007, 11:46 AM	#6
David Beale Senior Member Join Date: Jul 2006 Location: Edmonton Alberta Posts: 1,330 My Car: 2007 Prius Package: B Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Also remember the battery is a large block of metal, and it takes a long time to heat it up and a long time to cool it off once it's heated up. It isn't going to change temperature rapidly. It started at 100 F (ambient - and had all day to get there). You started using the battery, so it heated up a little more, but even if you blew 70 F air on it with a large fan it wouldn't cool off for at least an hour. The tiny fan the Prius uses is going to take a while to cool the battery. But at least it held the temp at 105 F while the car was using the battery. We don't get those kinds of temps. here, but one day we were at +30 C and I noticed a lower SOC, poorer mileage, and more ICE operation. Yes, I had A/C on - set to 27 C - even 30 C is too hot for me! Oh, and the Scangauge will not indicate traction battery temp or any other parameters. Those are "CAN" messages. The Scangauge only sees standard ODBII messages, such as coolant temp, 12V battery voltage, fuel use, etc. __________________ Edmonton Alberta "Pearl" is a 2007 Driftwood Pearl Prius.

08-09-2007, 01:49 PM	#8
Cheap! Senior Member Join Date: Apr 2006 Posts: 1,154 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 1	I use a “Fan Mod” on my fan to get it to go full bore when the OEM battery temperature gets above 94 deg. I want to modify it further to run as normal and then at my will, push a button to force it to full bore. The fan itself makes no noise, but the sucking air sound through the plenum is loud enough to be annoying if the radio is not on. Also, I have been looking into a direct tap modification to the AC/Heat vent to get the air into the battery compartment without mixing with the ambient passenger compartment air. I believe the Toyota guys should look into improving battery temperature management for the next Prius. Right now in Houston, the passenger compartment can reach 130 degrees and why would you want to grab that air. On the other hand out side temperatures are reaching 100 deg F. here. They need a system that would grab air from the best possible place depending on the batteries needs, whether it be from the inside, outside, or if it has to start up the AC/Heater, on it's own and grab the air from there. That system would be fairly complex (no more so then the regular AC vent system) but I think it would be helpful in there plug in version if it ever makes it to market. __________________ * Classic Silver, Prius Plus Plug-in Hybrid Electric Vehicle Conversion EV Button Free Reverse Beep Mod, Mirror Mod, Aerodynamic hubcaps, * Almost Free Anytime Reverse Video, Anytime Forward View Video, Fumoto F103N Oil Drain Valve, Almost Free Speed Wire Interrupt, Almost Free Navigation Override switch, Dual Microphone Mod In Dash DVD Theater, *V4 CAN-View </span> <span style="color:#FF0000">Mods wanted in the near future - Hydraulic Brake -Pressure Indicator -Hobbits Vacuum “Good vs. Bad” Driving Indicator

08-09-2007, 02:06 AM	#3
patsparks Uneducated bird-brain Aussie Join Date: Jul 2007 Location: Adelaide South Australia Posts: 4,425 My Car: 2004 Prius Package: Base Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 11	I wonder if having just the right rear window down would do the same thing? The wind would be right on the vent for the battery wouldn't it? This may force air through the battery better than the fan?

08-09-2007, 04:15 PM	#10
Green Hokie Senior Member Join Date: Mar 2007 Location: Glen Allen, VA Posts: 169 My Car: 2007 Prius Package: S Touring Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	That's it! I'm trading in my Prius for an Escape Hybrid. Just kidding, of course!