So close and yet so hot

Green Hokie · 08-03-2007, 02:36 PM

<div class='quotetop'>QUOTE(richard schumacher @ Aug 3 2007, 11:43 AM) [snapback]489943[/snapback]</div>

Quote:

...People who drive around with the A/C off and the windows down on hot days thinking that they are improving the fuel economy of their Prius are in sweaty error.
[/b]

I have to respectfully disagree with this. I'm sitting at 70.2 mpg right now with 663 miles driven so far on my current tank. I'm down to one solid bar on the fuel gauge and probably have another 30-40 miles before it will start flashing. This week, the temp in my area has been in the mid 90's. Driving home after work (at around 5pm) with the AC on (manual at the lowest fan speed & lowest temp setting), my mpg average would always drop below 70 mpg by the time I got home. With the AC off and all windows down, my average mpg always climbs by the time I get home. Therefore, I have not yet experienced the drop in FE with a "hotter" running car/battery, as some others have observed. Therefore, I have a hard time believing that using AC will ever improve FE (regardless of the driving condition) versus not using AC.

**efusco** · 08-03-2007, 02:51 PM

Oh, I feel strongly there are temps where battery performance, like Tony described in the OP, drops off. But I agree, in general, that that will be at temps only over about 105-110...about the point where the cooling fans kick on.

But I, too, tolerate temps up to around 90 when I can. Just remember that when it's 90 outside and the sun's shining and the windows are up that interior temps can get much hotter. A car in the sun all day may start with a battery temp of 120+, this is clearly inefficient and car behavior will be adversely affected.

This is another one of those times where having a CAN-View is very nice so one can see exactly what's going on.

Green Hokie · 08-03-2007, 03:16 PM

<div class='quotetop'>QUOTE(efusco @ Aug 3 2007, 02:51 PM) [snapback]490062[/snapback]</div>

Quote:

...This is another one of those times where having a CAN-View is very nice so one can see exactly what's going on.
[/b]

Thanks, Evan. Will ScanGauge II measure battery temp? I am think of getting one instead of CAN-View, due to cost & ease of installation.

qbee42 · 08-03-2007, 03:30 PM

<div class='quotetop'>QUOTE(paulccullen @ Aug 3 2007, 10:58 AM) [snapback]489916[/snapback]</div>

Quote:

No disrespect Tony, but are you crazy?
[/b]

You have to ask?!? :P

Tom

Cheap! · 08-03-2007, 04:34 PM

This is what I have been seeing since last weekend. I had a horrible MPG day on Saturday, in fact all day Saturday. I live in Houston. Of course I normally drive with the windows down. Now I grew up on Long Island and when I first got here I was only miserable when the temps were above 80 deg. F. Now after many years of 90 days straight, each year, of three digit temperatures, I am use to driving with just the windows down up to 95 deg. F.

The high temperatures are the problem. I can’t get EV except only in the mornings for the first few miles into work. I have been trying to keep the AC on, but by the time the air gets to the intake vent in the back, it is already heated up, so it takes a very long time for my AC to cool the car down enough to then put cool air on the battery.

I have been working on a solution to this problem. I plan to somehow tap in with a small tube into the plenum and run it along my door jam, or even maybe under the car and then feed it into the battery vent intake plenum. I have a more intricate design that would snake back and forth across the roof, above the liner, to cool that first and to limit the affect solar radiation has on the passenger compartment. Then it would go down one side behind the plastic and into the battery plenum.

Now the PHEV conversion I have does modify the Prius battery fan to run faster, even full blast, but if it is only blowing hot air, what good does that do? I have noticed that the cut off for EV mode, on my pack temperature is about 114 - 116 deg. F. on the Can-View.

I of course will do a temporary tap from the AC vent, through the tube, over the passenger seat, over the back seat directly to the intake vent. However that will have to wait for a little while, and for a time that my wife is not in the car. I’ll post pictures.

priussoris · 08-03-2007, 04:46 PM

Tony,
with the title of this thread I thought I was going to report it to the MODS.

**efusco** · 08-03-2007, 05:01 PM

<div class='quotetop'>QUOTE(Green Hokie @ Aug 3 2007, 02:16 PM) [snapback]490072[/snapback]</div>

Quote:

Thanks, Evan. Will ScanGauge II measure battery temp? I am think of getting one instead of CAN-View, due to cost & ease of installation. [/b]

Not yet, but word has it that it will start having hybrid info...I don't know if it will be a programmable upgrade to the II or if it'll be a third generation update. You might be able to call the ScanGuage guy and find out.

Green Hokie · 08-03-2007, 06:00 PM

<div class='quotetop'>QUOTE(efusco @ Aug 3 2007, 05:01 PM) [snapback]490144[/snapback]</div>

Quote:

Not yet, but word has it that it will start having hybrid info...I don't know if it will be a programmable upgrade to the II or if it'll be a third generation update. You might be able to call the ScanGuage guy and find out.
[/b]

Thank you! I'll do just that before deciding to order. Wouldn't mind waiting a few months or so if it'll end up being a new 3rd gen unit.

And oh, my apologies to Tony for sort of hijacking his thread.

**TonyPSchaefer** · 08-03-2007, 08:40 PM

Quote:

And oh, my apologies to Tony for sort of hijacking his thread. [/b]

No prob.

Does anyone know the UV rating on the windows?
Sounds odd, I know, but since I work due South of where I live, the sun is ALWAYS to my left in the morning and ALWAYS to my left when I'm coming home. And to make matters worse, it's almost ALWAYS in that gap between the visor and the door jam.

I have been working under the impression that there's at least some level of UV protection in the window. No facts, just optimistic hoping. Even when I row down the windows, I normally don't put down the driver's window because - if you've met me you know - I'm extremely white and burn easily. During the course of a one-hour drive, five times a week (10 hours of sun time total per week), I'm sure that I would either sunburn or at least have an oddly dark left side of my face.

hobbit · 08-03-2007, 10:36 PM

Mike Dabrowski did an A/C-vent-redirect in his Insight, when he
figured he would need extra cooling when making the pack work harder
with MIMA. Similar type of air inlet, behind the passenger seat.
.
I've been thinking how absolutely stupid it is that the interior of
the car picks up so much heat, while the engine block tends to stay
fairly cool even on a hot day. We want the exact *opposite*, and it
would be lovely if there was a way to pick up all that cabin heat
before it becomes cabin heat and send it all to the engine coolant.
Year-round EBH users wouldn't need to plug it in on hot days.
Unfortunately, it would involve a fairly complex pickup structure,
or maybe some sort of black rubber mat with water channels you'd
throw over the whole car and hook into the cooling system somehow..
.
_H*

08-03-2007, 02:51 PM	#12
efusco Troll Slayer Join Date: Nov 2003 Location: Nixa, MO Posts: 14,708 My Car: 2004 Prius Package: #9 Nominated 1 Time in 1 Post TOTM Awards: 0 Friends: 26	Oh, I feel strongly there are temps where battery performance, like Tony described in the OP, drops off. But I agree, in general, that that will be at temps only over about 105-110...about the point where the cooling fans kick on. But I, too, tolerate temps up to around 90 when I can. Just remember that when it's 90 outside and the sun's shining and the windows are up that interior temps can get much hotter. A car in the sun all day may start with a battery temp of 120+, this is clearly inefficient and car behavior will be adversely affected. This is another one of those times where having a CAN-View is very nice so one can see exactly what's going on. __________________ Evan E. Fusco, MD Seaside 04BC9/OEM EVb/NAV & auto-BT/XM Radio, CAN-View, Shark Fin, BT Stiff. Plate, Skid Plate & Strut Support

08-03-2007, 04:34 PM	#15
Cheap! Senior Member Join Date: Apr 2006 Posts: 1,157 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 4	This is what I have been seeing since last weekend. I had a horrible MPG day on Saturday, in fact all day Saturday. I live in Houston. Of course I normally drive with the windows down. Now I grew up on Long Island and when I first got here I was only miserable when the temps were above 80 deg. F. Now after many years of 90 days straight, each year, of three digit temperatures, I am use to driving with just the windows down up to 95 deg. F. The high temperatures are the problem. I can’t get EV except only in the mornings for the first few miles into work. I have been trying to keep the AC on, but by the time the air gets to the intake vent in the back, it is already heated up, so it takes a very long time for my AC to cool the car down enough to then put cool air on the battery. I have been working on a solution to this problem. I plan to somehow tap in with a small tube into the plenum and run it along my door jam, or even maybe under the car and then feed it into the battery vent intake plenum. I have a more intricate design that would snake back and forth across the roof, above the liner, to cool that first and to limit the affect solar radiation has on the passenger compartment. Then it would go down one side behind the plastic and into the battery plenum. Now the PHEV conversion I have does modify the Prius battery fan to run faster, even full blast, but if it is only blowing hot air, what good does that do? I have noticed that the cut off for EV mode, on my pack temperature is about 114 - 116 deg. F. on the Can-View. I of course will do a temporary tap from the AC vent, through the tube, over the passenger seat, over the back seat directly to the intake vent. However that will have to wait for a little while, and for a time that my wife is not in the car. I’ll post pictures. __________________ * 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

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08-03-2007, 04:46 PM	#16
priussoris Join Date: Apr 2007 Posts: 1,005 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Tony, with the title of this thread I thought I was going to report it to the MODS.

08-03-2007, 10:36 PM	#20
hobbit Senior Member Join Date: Mar 2005 Location: Bahstahn Posts: 3,012 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Mike Dabrowski did an A/C-vent-redirect in his Insight, when he figured he would need extra cooling when making the pack work harder with MIMA. Similar type of air inlet, behind the passenger seat. . I've been thinking how absolutely stupid it is that the interior of the car picks up so much heat, while the engine block tends to stay fairly cool even on a hot day. We want the exact opposite, and it would be lovely if there was a way to pick up all that cabin heat before it becomes cabin heat and send it all to the engine coolant. Year-round EBH users wouldn't need to plug it in on hot days. Unfortunately, it would involve a fairly complex pickup structure, or maybe some sort of black rubber mat with water channels you'd throw over the whole car and hook into the cooling system somehow.. . _H*