Extremely low mileage in below 16 degrees
#21
01-18-2009, 10:31 AM
Re: Extremely low mileage in below 16 degrees
As you may have noted, read, there was a previous post wherein the owner noticed that the ICE was consistently running in higher RPM ranges in cold climates. My explanation, "theory" was/is that was the case since the ICE had to be used for recharging the battery since regen was incapable due to the low OAT.
I had regen/assist and the RPMS were not notably higher once I achieved warm-up (around 10 miles).
I have noticed on the Prius that on long hwy drives when there is not regen opportunity the control system will let the SOC deplete down to about 1/2 and then decide it must make use of FUEL for recharging. If I remember well/correctly, this "cycle" occurred about 3 or 4 times on the trip to Portland from Seattle on I5.
The battery charge indicator on the NAVI stayed at its normal level while I was at steady state (~80% of the display indicator, I know that doesn't equal 80% battery SOC but it's all I have available as a SOC indicator) . It went up to ~90% (along with the indicators showing charge/regen) when I had to slow down for several speed zones and traffic lights and down when I pulled off from the stop in EV. Since I have the hybrid NAVI display, I can tell when the system is in the different modes (EV/regen/assist/ICE only/mixed). All of these drive types were displayed as normal throughout the drive.
Apparently the early Prius firmware is designed to "wait" as long as is reasonable for a regen opportunity to arise and if that doesn't happen then the ICE is used. In your case not far into your COLD drive the ECU would "know" that no regen was likely to become available so it might use the ICE continuously.
Once again, the NAVI display indicated this was not the case on the FEH in this scenario. Regen was available as per the NAVI display and the charge/Assist gauge.
Since you didn't make mention of noting anything of this nature I assume you didn't pay attention to ICE RPM vs road speed...
But its probably worth asking...
Yes, I did pay attention as I'm an old school driver that listens to every sound a car makes and constantly monitors the gauges (I also own an old MG and you don't have any other choice with a car like that
). The RPMS were higher during the warm-up period but after that I was cruising at 45-60MPG with the standard 1700-2200RPM (varies depending on road inclination and driver demand). I use the FS often to get the ~1700RPM once I'm at speed and level.
I should also mention that while I was driving I could hear the battery vent fan running (if I concentrated on that area and sound). This indicates to me that the system had ample heat in the battery pack. (Note that Ford has done an excellent job with hiding this fan noise by matching it's use/RPM with ICE and road speed. The ambient ICE, tire and road noise is used to hide the fan)
I had regen/assist and the RPMS were not notably higher once I achieved warm-up (around 10 miles).
I have noticed on the Prius that on long hwy drives when there is not regen opportunity the control system will let the SOC deplete down to about 1/2 and then decide it must make use of FUEL for recharging. If I remember well/correctly, this "cycle" occurred about 3 or 4 times on the trip to Portland from Seattle on I5.
The battery charge indicator on the NAVI stayed at its normal level while I was at steady state (~80% of the display indicator, I know that doesn't equal 80% battery SOC but it's all I have available as a SOC indicator) . It went up to ~90% (along with the indicators showing charge/regen) when I had to slow down for several speed zones and traffic lights and down when I pulled off from the stop in EV. Since I have the hybrid NAVI display, I can tell when the system is in the different modes (EV/regen/assist/ICE only/mixed). All of these drive types were displayed as normal throughout the drive.
Apparently the early Prius firmware is designed to "wait" as long as is reasonable for a regen opportunity to arise and if that doesn't happen then the ICE is used. In your case not far into your COLD drive the ECU would "know" that no regen was likely to become available so it might use the ICE continuously.
Once again, the NAVI display indicated this was not the case on the FEH in this scenario. Regen was available as per the NAVI display and the charge/Assist gauge.
Since you didn't make mention of noting anything of this nature I assume you didn't pay attention to ICE RPM vs road speed...
But its probably worth asking...
Yes, I did pay attention as I'm an old school driver that listens to every sound a car makes and constantly monitors the gauges (I also own an old MG and you don't have any other choice with a car like that
). The RPMS were higher during the warm-up period but after that I was cruising at 45-60MPG with the standard 1700-2200RPM (varies depending on road inclination and driver demand). I use the FS often to get the ~1700RPM once I'm at speed and level.I should also mention that while I was driving I could hear the battery vent fan running (if I concentrated on that area and sound). This indicates to me that the system had ample heat in the battery pack. (Note that Ford has done an excellent job with hiding this fan noise by matching it's use/RPM with ICE and road speed. The ambient ICE, tire and road noise is used to hide the fan)
#22
01-18-2009, 10:57 AM
Re: Extremely low mileage in below 16 degrees
I don't own a FEH either. Is it alright if I post here or is FEH ownership a requirement to post in this section?
I can only speak for myself but you're welcome to post here but if a majority of people are asking you to leave, I hope you would take common courtesy and withhold your further input.
While the cold does effect certain hybrid functions (like auto-stop), non-hybrid vehicles suffer from poor mileage in the cold just like hybrids.
I agree that all vehicles will be affected by cold weather and expecting the same FE is not wise. With that said I'd like to address your list WRT the driving scenario I posted. Once again, I don't disagree with what you have said as it pertains to most cold weather driving scenarios.
The decrease in MPG is caused by:
1) Non moving warm up time.
Crank and drive time for me is always <5 seconds. I dont' believe in allowing the FEH to "warm up" while standing still. I know that ICE work better at a given temperature (thus thermostats, heat range spark plugs, etc.) but I also expect that the new use of ECU, fule injection, electronic variable ignition and timing, that simply sitting around for warmup is not as needed as it once was.
2) Engines all run rich till they warm up, thus consuming more fuel. In the Summer my car is warmed up within the first mile. In the Winter it can take up to 8 or 9 miles for the car to warm up to full operating temperature.
Agreed. I did see higher RPMs during the first 10 miles of the trip. I like to use the heated seat and multiple layers to keep me warm during this period and I try not to use the ICE heat until I feel that the engine has gotten to a point where the thermostat has opened and ICE heat will be "wasted" via the radiator and would otherwise be more efficiently used to heat me (and the battery pack via higher cabin air temperature)
3) Lube gets stiffer and take more energy to overcome friction.
Agreed. But I would expect that these lubes would reach a relatively warm and happy temperature about the same time that the ICE does. Maybe it's a little longer but when lubes are cold, friction is increased and friction when overcome creates heat. Thus in my mind the lube should at some point heat and then have it's normal resistence. I'm sure I drove past that distance on either leg of my trip.
4) If you don't put more air in your tires PV=nRT will cause your tires to be under inflated in the Winter adding to rolling resistance.
Agreed. I did check my air pressure before the trip (since I knew it was going to be a longer drive than normal) and they were within the range that I wanted them. I recently raised the presure and even with the cold air I would still be above the pressure I was running during the 40MPG runs.
5) If there is snow on the road this will increase rolling resistance (a lot) as well.
Agreed. But in this case there dry roads and no noticable wind forces. I assume that you could factor in that the cold air was just plain denser and therefore hardre to cut through. The FEH is a bit of a brick when compared to most of the other hybrids (but note the Highlander and the GM big hybrids).
I can only speak for myself but you're welcome to post here but if a majority of people are asking you to leave, I hope you would take common courtesy and withhold your further input.
While the cold does effect certain hybrid functions (like auto-stop), non-hybrid vehicles suffer from poor mileage in the cold just like hybrids.
I agree that all vehicles will be affected by cold weather and expecting the same FE is not wise. With that said I'd like to address your list WRT the driving scenario I posted. Once again, I don't disagree with what you have said as it pertains to most cold weather driving scenarios.
The decrease in MPG is caused by:
1) Non moving warm up time.
Crank and drive time for me is always <5 seconds. I dont' believe in allowing the FEH to "warm up" while standing still. I know that ICE work better at a given temperature (thus thermostats, heat range spark plugs, etc.) but I also expect that the new use of ECU, fule injection, electronic variable ignition and timing, that simply sitting around for warmup is not as needed as it once was.
2) Engines all run rich till they warm up, thus consuming more fuel. In the Summer my car is warmed up within the first mile. In the Winter it can take up to 8 or 9 miles for the car to warm up to full operating temperature.
Agreed. I did see higher RPMs during the first 10 miles of the trip. I like to use the heated seat and multiple layers to keep me warm during this period and I try not to use the ICE heat until I feel that the engine has gotten to a point where the thermostat has opened and ICE heat will be "wasted" via the radiator and would otherwise be more efficiently used to heat me (and the battery pack via higher cabin air temperature)
3) Lube gets stiffer and take more energy to overcome friction.
Agreed. But I would expect that these lubes would reach a relatively warm and happy temperature about the same time that the ICE does. Maybe it's a little longer but when lubes are cold, friction is increased and friction when overcome creates heat. Thus in my mind the lube should at some point heat and then have it's normal resistence. I'm sure I drove past that distance on either leg of my trip.
4) If you don't put more air in your tires PV=nRT will cause your tires to be under inflated in the Winter adding to rolling resistance.
Agreed. I did check my air pressure before the trip (since I knew it was going to be a longer drive than normal) and they were within the range that I wanted them. I recently raised the presure and even with the cold air I would still be above the pressure I was running during the 40MPG runs.
5) If there is snow on the road this will increase rolling resistance (a lot) as well.
Agreed. But in this case there dry roads and no noticable wind forces. I assume that you could factor in that the cold air was just plain denser and therefore hardre to cut through. The FEH is a bit of a brick when compared to most of the other hybrids (but note the Highlander and the GM big hybrids).
I, for one, thank you for your input.
#23
01-18-2009, 03:24 PM
Ridiculously Active Enthusiast
Join Date: Sep 2006
Location: Beautiful Pacific NW
Posts: 1,678
Re: Extremely low mileage in below 16 degrees
]"..but if a majority of people are asking you to leave.."
How does one determine when a majority vote has been reached...??
Number of posts/posters....or number of views vs posts...??
Number of posters for a given thread are clearly in the minority compared to the number of views(readers..??)....
How does one determine when a majority vote has been reached...??
Number of posts/posters....or number of views vs posts...??
Number of posters for a given thread are clearly in the minority compared to the number of views(readers..??)....
#25
01-18-2009, 04:50 PM
Ridiculously Active Enthusiast
Join Date: Sep 2006
Location: Beautiful Pacific NW
Posts: 1,678
Re: Extremely low mileage in below 16 degrees
That's undoubtedly the BEST procedure to use....
#26
01-21-2009, 03:13 PM
Re: Extremely low mileage in below 16 degrees
He is on my "ignore" list, so I don't see his posts any more unless someone replies.
#27
01-21-2009, 08:19 PM
Re: Extremely low mileage in below 16 degrees
3) Lube gets stiffer and take more energy to overcome friction.
Thing is the lube in the wheels bearings gets stiffer too. In the Winter a car just won't coast as far as in Summer, even after a long drive. That the car is coasting eliminates all ICE and hybrids parts (if equipped) as a source of additional friction.
Part of it could be increased air friction but that would only account for the high speed aspect. At lower speeds it must be the stiffening of the wheel bearing lube, near as I can tell anyhow...
I image the wheels act like big ole heat sinks and that is what keeps the wheel bearing grease so cold/stiff even on a long drive. In fact I suspect (but do not know for sure) that stiff wheel bearing grease is one of the larger factors contributing to poor winter mileage.
Last edited by BigTuna; 01-21-2009 at 08:22 PM.
#28
01-21-2009, 08:31 PM
Re: Extremely low mileage in below 16 degrees
Why on earth would you assume that? How would I know about the effects of cold weather and snow on MPG if I'd never driven in cold/snowy conditions?
#29
01-27-2009, 01:08 PM
Re: Extremely low mileage in below 16 degrees
I recently made the same trip to Kansas City. The temperatures were about an average of 28 degrees on the way there and 17 degrees on the way home. I tried to keep the MPH to about 68. I normally get about 35 MPG in 60 degrees. This trip I received 26MPG on the way there and 25MPG on the way home. The trip is about 4 hours long with no stops. The RPM's were regularly 3000 to go 68 MPH. In my previous post, I averaged about 20MPG and it was 6 degrees.
I have been to the dealer three times and they have no suggestions. I am ready to get rid of this car and it only has 7000 miles
I have been to the dealer three times and they have no suggestions. I am ready to get rid of this car and it only has 7000 miles
#30
01-27-2009, 04:40 PM
Re: Extremely low mileage in below 16 degrees
All engines will do poorly in cold weather. One of my first cars actually had a 'choke' lever that I had to set to start the car in the winter, back it off a click after starting and let it run a few minutes, then back it off slightly more after it had run a few miles, and I couldn't shut it off completely until the car had been running may be 5-10 miles depending on the temps.
The choke enriches the fuel mixture. Modern cars have no 'choke' or 'throttle' levers anymore... but not because the physics of the universe have changed... but because the wonderful computer figures out what the right mixture needs to be and is able to blend it to the point that we get "warmed up" car acceleration when a car built years ago would have very poor performance until it warmed up.
I wouldn't think about the temp of engine & drive-train lube friction too much, the bigger problem is "thermal mass". While fluids are trying to warm up, the ice-cold steel is trying to wick that heat right back out. The more thermal mass, the longer it takes (and more energy) to affect change. Frankly a tiny engine warms up faster (also cools down faster).
You can help your car by blocking the grille to reduce airflow through the radiator and engine compartment. This will slow down how quickly the heat can dissipate, resulting in a shorter warm-up time and maybe even boost some driver happiness because the heater can produce warm air inside the car faster.
There are lots of other little factors... anything that draws power is going to reduce economy, so the rear-window defroster that probably needs to run 15 minutes, the front-window defroster which force the AC to run in virtually any car sold in the US, seat-heaters, etc. will all chip away. The tires will lose about a pound of pressure per 10 degrees of temperature drop and that means your "perfectly inflated" tires at 80 degrees in the summer are now all under-inflated by about 7 pounds each.
While your car is getting worse economy in frigid temps, keep in mind that EVERY car is getting awful economy in frigid temps. You're not doing nearly as bad as the guy next to you.
The choke enriches the fuel mixture. Modern cars have no 'choke' or 'throttle' levers anymore... but not because the physics of the universe have changed... but because the wonderful computer figures out what the right mixture needs to be and is able to blend it to the point that we get "warmed up" car acceleration when a car built years ago would have very poor performance until it warmed up.
I wouldn't think about the temp of engine & drive-train lube friction too much, the bigger problem is "thermal mass". While fluids are trying to warm up, the ice-cold steel is trying to wick that heat right back out. The more thermal mass, the longer it takes (and more energy) to affect change. Frankly a tiny engine warms up faster (also cools down faster).
You can help your car by blocking the grille to reduce airflow through the radiator and engine compartment. This will slow down how quickly the heat can dissipate, resulting in a shorter warm-up time and maybe even boost some driver happiness because the heater can produce warm air inside the car faster.
There are lots of other little factors... anything that draws power is going to reduce economy, so the rear-window defroster that probably needs to run 15 minutes, the front-window defroster which force the AC to run in virtually any car sold in the US, seat-heaters, etc. will all chip away. The tires will lose about a pound of pressure per 10 degrees of temperature drop and that means your "perfectly inflated" tires at 80 degrees in the summer are now all under-inflated by about 7 pounds each.
While your car is getting worse economy in frigid temps, keep in mind that EVERY car is getting awful economy in frigid temps. You're not doing nearly as bad as the guy next to you.
