A/C Usage and Impact on FE - Page 3 - Fuelly Forums

Click here to see important news regarding the aCar App

Reply
 
Thread Tools Display Modes
 
Old 07-01-2009, 04:39 AM   #21
Registered Member
 
shatto's Avatar
 
Join Date: Sep 2008
Posts: 345
Country: United States
1.Rain.
At the family holiday feast preparations, the kid asked his mom why she cut the ends off the ham then tucked them in the pan before baking. She replied that that is what she learned form watching her mom, and to ask grandma. Grandma's reply was the same as the daughter so she turned and asked the Matriarch of the family, the Great Grandmother who replied; small pan.

People still drive in the rain with the windows open.
Great Grandpa didn't have Air Conditioning that automatically ran with the defroster to remove the window-fogging humidity.......

Water on roads dramatically reduces free rolling. Ever hit a puddle at speed?
Better MPG might be because we drive slower?

2. Using the A/C.
I missed the part about the reduction in MPG caused by the drag of having open windows...even a little bit.

I didn't see the part where the ScanGauge was compared to actual arithmetic involving real miles and real gallons.


But, silly me...
I got rid of my Dakota because the A/C broke and it cost more than the truck was worth to fix it.
To me, the conversation is academic. I chose comfort.
__________________

__________________
I use and talk about, but don't sell Amsoil.
Who is shatto?
06 4.7 Tundra replaced a 98 Dakota 3.9.
623,000 miles on original engine and transmission, using Amsoil by-pass filters and lubrication.
+Everybody knows something you don't know.
+Artists prove truth can be in forms you don't understand.

Low-Risk Option Trader
Retired Pro-Hunter featured in; 'African Hunter', by James R. Mellon III. and listed in; Rowland Ward's Records of Big Game.
shatto is offline   Reply With Quote
Old 07-01-2009, 04:50 AM   #22
Registered Member
 
theholycow's Avatar
 
Join Date: Apr 2008
Posts: 6,624
Country: United States
Send a message via ICQ to theholycow Send a message via AIM to theholycow Send a message via MSN to theholycow Send a message via Yahoo to theholycow
Quote:
Originally Posted by shatto View Post
To me, the conversation is academic. I chose comfort.
Me too. Besides, it evens out in the end; I'm a more patient driver and more able to save gas when I'm more comfortable.
__________________

__________________
This sig may return, some day.
theholycow is offline   Reply With Quote
Old 07-01-2009, 06:05 AM   #23
Site Team / Moderator
 
Jay2TheRescue's Avatar
 
Join Date: Sep 2008
Location: Northern Virginia
Posts: 4,719
Country: United States
Location: Northern Virginia
I totally agree. If I'm not comfortable there is no way I'm going to hypermile. I'm going to get to my destination as quick as possible.

-Jay
__________________








Jay2TheRescue is offline   Reply With Quote
Old 07-01-2009, 06:26 AM   #24
Registered Member
 
Join Date: Nov 2007
Posts: 1,852
Country: United States
Location: north east PA
{Bottom line is the more efficient cars become the much greater the cost of running the AC. It's more exponential than linear and if we ever build mega mileage cars we will also have to address the gross inefficiency of conventional AC systems, even with the best modern designs of compressor.}

I believe this only applies to traditional belt driven ACs. The Prius uses a variable speed electric compressor. It doesn't directly suck off energy going from the engine to the wheels. There will be a mpg penalty of some type, since the energy it takes from the battery has to be replenished in someway, but then the battery is cooled by the cabin air. So AC use may keep it at a more efficient point.

I've heard BMW was experimenting with regenerative braking on non-hybrid cars to run accessories. With the regen brakes and a beefy battery, it may be possible to replace all the belt driven add-ons with electric.
trollbait is offline   Reply With Quote
Old 07-01-2009, 08:44 AM   #25
Registered Member
 
JanGeo's Avatar
 
Join Date: Jan 2006
Posts: 2,444
Country: United States
Location: Tiverton, RI
Send a message via Yahoo to JanGeo
Driving in rain helps mileage a little sometimes - a little water on the road makes it more slick and lubricates the tread reducting traction and lowering rolling resistance a little and raising the MPG - however if it gets too deep then it can slow you down. It also adds moisture to the combustion which helps generate more power in the engine. Using a little heat for the defroster keeps the windshield clear but since the cars have gone to a single stupid control for the vents you can't get warm air on the windshield and cold air on you like my old VW Rabbit with the separate fresh air vents that only put out cold air and separate control levers for feet and windshield. Ahhh those were the simpler days when a simple lever turned something on and off as much or as little as you wanted. Now you have dash - dash and feet - feet - feet and windshield with defrost - windshield with defrost.
JanGeo is offline   Reply With Quote
Old 07-01-2009, 09:54 AM   #26
Registered Member
 
theholycow's Avatar
 
Join Date: Apr 2008
Posts: 6,624
Country: United States
Send a message via ICQ to theholycow Send a message via AIM to theholycow Send a message via MSN to theholycow Send a message via Yahoo to theholycow
Adding moisture to the air/fuel mix might help.

Rolling resistance, AFAIK, is not caused by tread friction on the road (and if it was, tires would never last 40,000 miles). It's caused by having to deform the sidewall at the bottom.

I sure would like separate controls for things.
__________________
This sig may return, some day.
theholycow is offline   Reply With Quote
Old 07-01-2009, 02:44 PM   #27
Registered Member
 
bowtieguy's Avatar
 
Join Date: Oct 2008
Posts: 1,873
Country: United States
Location: orlando, florida
Quote:
Originally Posted by theholycow View Post
Why would rain decrease rolling resistance? I can only imagine it making more rolling resistance as the tire has to displace the water...
i'm thinking light rain and/or roads w/ good drainage keeping standing water to little or nothing.

oh, and we call slick roads at the beginning of rainfall "black ice" in FL.
bowtieguy is offline   Reply With Quote
Old 07-04-2009, 07:47 PM   #28
Registered Member
 
Join Date: Apr 2009
Posts: 52
Country: United States
Quote:
Originally Posted by Jay2TheRescue View Post
I think larger engines don't suffer as much... I tested this a year or 2 ago. Drove my truck on its daily drive, with the A/C on max for a week, then drove it with the a/c off and windows up for a week and noticed no difference in my mileage.

-Jay
i can vouch for that, i take a hit of about 4-6mpg in my civic running the a/c. my explorer is almost un noticeable.
__________________
nate sanders

the less throttle you give, the more mileage you get!
hi tech hillbilly is offline   Reply With Quote
Old 07-05-2009, 05:40 PM   #29
Registered Member
 
Join Date: Jan 2007
Posts: 104
Country: Canada
The differences are insignificant in my cars. The Matrix is small but I think the electric compressor used in it instead of a belt driven one helps. However, its cooling effect is not exceedingly strong at the same time.
swng is offline   Reply With Quote
Old 07-06-2009, 09:25 AM   #30
Registered Member
 
KARR's Avatar
 
Join Date: Sep 2008
Posts: 73
Country: Portugal
Location: Algarve
Light rain may improve mileage since it cools down the road surface turning it less sticky than in a hot day. As you all know, tarmac may start melting if the temperature is high enough.

Heavy rain will decrease mileage even if the tarmac has cooled down, for the reasons mentioned.
__________________

KARR is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
New personal best today 96hb General Fuel Topics 14 05-29-2008 07:35 AM

» Fuelly iOS Apps
Powered by vBadvanced CMPS v3.2.3


All times are GMT -8. The time now is 01:16 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.