Go Back   EcoModder Forum > EcoModding > Hypermiling / EcoDriver's Ed
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 08-09-2012, 08:31 PM   #1 (permalink)
EcoModding Lurker
 
Join Date: Aug 2012
Location: Canada
Posts: 3

Ridge - '06 Honda Ridgeline RTL
Thanks: 0
Thanked 0 Times in 0 Posts
A/C? (instantaneous mpg drops between 4 and 6 mpg with AC on)

Hey everyone!
I just got back from an 800+km trip.
I have the PLX Kiwi monitoring my mpg.
On the last leg of my journey, I decided to play around with my A/C.
I noticed that on a consistent flat road, when I turned on my a/c, my instantaneous mpg went down between 4 and 6 mpg. (depending on the road)
I am totally a newb. At tech school we were taught that a/c didn't take away power or mpg. This blew my mind!
Has anyone had a similar experience?
Also, I challenge you to find the flattest road you can and set your cruise and test it. A/C on and off. See what your mpg does.
Thanks for being patient if this is a total newb question!

- Buzz

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 08-09-2012, 08:58 PM   #2 (permalink)
40-60-40 MPH P&G
 
echo-francis's Avatar
 
Join Date: Feb 2011
Location: laval, QC
Posts: 277

Echo-P&G - '05 Toyota Echo base
Team Toyota
90 day: 82.76 mpg (US)
Thanks: 45
Thanked 113 Times in 58 Posts
i did this test sometimes ago and i get a minimum 6 mpg drop
__________________
Best Tank (1557.2 Km): 2.57 LHK (91.63 MPG (US) )
Best Highway Trip (~36.8 Km): 2.16 LHK (109 MPG (US) )
Best Commute Trip avg (73.8 Km ): 2.33 LHK (101 MPG (US) )
Echo-Troll Modding Thread

I know i dont have a very good write-up
no lean-burn? no good gear ratio? p&g is the answer
MPG=1 TIME=0
  Reply With Quote
Old 08-09-2012, 08:59 PM   #3 (permalink)
Master EcoModder
 
Join Date: Sep 2009
Posts: 5,927
Thanks: 877
Thanked 2,024 Times in 1,304 Posts
It varies from vehicle to vehicle. In my 02 Insight it was a 10 MPG hit, even when you set it on recirc, with low fan speed and just enough temp to be barely comfortable. On my Fiesta its much less, probably barely over 1 MPG. The manufacturers have done a lot with compressor technology as well as orfices instead of expansion valves to reduce the power requirements dramatically. The Fiesta is tolerable on low fan, recirculate, with the temp knob about 25% above max cool. I actually watched the instant MPG reading climb to 46.7 MPG running the AC the last time we rode in the Fiesta. In my Insight it would beat that MPG by about 7 MPG, not a huge difference.

regards
Mech
  Reply With Quote
Old 08-10-2012, 09:14 AM   #4 (permalink)
Master EcoModder
 
Join Date: Jan 2011
Location: na
Posts: 1,025
Thanks: 277
Thanked 218 Times in 185 Posts
With the Cobalt, I've only recorded one trip with AC on, it was 42(why record bad trips) vs same trip without AC averages about 48, trip average speed is about 50 mph. Comes to about 12% loss.

At idle gph goes from 0.3 to 0.4 no air vs air. So just for comparison. Changing the average speed to 48 mph to make the math easier, without air I use a gallon per hour. If with air I use 1.1 gallons to go the same 48 miles I get 43.6 mpg. (9% loss)

AC setting pretty much same as Old Mech, I'm usually ok until temps in 90's, and I get to park in the drive thru at work so car isn't really hot when I leave.
  Reply With Quote
Old 08-10-2012, 09:24 AM   #5 (permalink)
Administrator
 
Daox's Avatar
 
Join Date: Dec 2007
Location: Germantown, WI
Posts: 11,203

CM400E - '81 Honda CM400E
90 day: 51.49 mpg (US)

Daox's Grey Prius - '04 Toyota Prius
Team Toyota
90 day: 49.53 mpg (US)

Daox's Insight - '00 Honda Insight
90 day: 64.33 mpg (US)

Swarthy - '14 Mitsubishi Mirage DE
Mitsubishi
90 day: 56.69 mpg (US)

Daox's Volt - '13 Chevrolet Volt
Thanks: 2,501
Thanked 2,585 Times in 1,553 Posts
Quote:
Originally Posted by buzz_42 View Post
At tech school we were taught that a/c didn't take away power or mpg. This blew my mind!
Sorry, but your tech school is 100% wrong. Energy to do anything has to come from somewhere. That place on a car is your engine. To do anything requires power from it.

Frank Lee posted up some good info on the A/C penalty a while back.

http://ecomodder.com/forum/showthrea...ighlight=a%2Fc
__________________
Current project: A better alternator delete
  Reply With Quote
Old 08-10-2012, 01:29 PM   #6 (permalink)
Master EcoModder
 
Join Date: Jan 2011
Location: na
Posts: 1,025
Thanks: 277
Thanked 218 Times in 185 Posts
I wonder if the Tech Teacher really meant AC doesn't hurt mpg anymore than the aero penalty for having windows rolled down?
  Reply With Quote
Old 08-10-2012, 01:50 PM   #7 (permalink)
Master EcoModder
 
Join Date: Sep 2009
Posts: 5,927
Thanks: 877
Thanked 2,024 Times in 1,304 Posts
I kill the compressor when I am idling and let the fan blow over the cool evaporator. My car also stays in my garage so it is always cool when we start off, except when we park somewhere in the sunshine. The Fiesta made one 50 mile trip this week, while the motorcycle went 215 miles at 90.84 MPG. I don't intentionally ride the bike in the rain, but I have become good at watching the weather radar and dodging the storms we have almost daily this time of year.

regards
Mech
  Reply With Quote
Old 08-10-2012, 02:12 PM   #8 (permalink)
EcoModding Lurker
 
jalmir's Avatar
 
Join Date: Aug 2012
Location: Montreal
Posts: 60

Avante - '02 Hyundai Elantra GT
90 day: 32.07 mpg (US)
Thanks: 1
Thanked 8 Times in 8 Posts
On my 2002 Elantra I know it take a LOT of power from the engine, never checked the MPG but when I turn the A/C on you feel the car jerk "back" right away (it slows down quite a bit). This is a know problem on this generation (2001 to 2006) but it was fixed later (2007 and up).

My best FE with the A/C on was 6.4l/100km (almost 37 MPG) on a highway trip, so I'm guessing I could've easilly gotten above 40 MPG if I had turned the A/C off!
  Reply With Quote
Old 08-10-2012, 02:50 PM   #9 (permalink)
Wiki Mod
 
Weather Spotter's Avatar
 
Join Date: Nov 2009
Location: Midland MI, USA
Posts: 2,042

Max - '14 Ford C-Max SEL
Thanks: 228
Thanked 304 Times in 210 Posts
On my matrix its a 4-6 MPG drop with AC on. windows down is no drop up to 60 MPH. since I am almost never over that speed when its hot out my ac stays off.
__________________
  Reply With Quote
Old 08-12-2012, 03:55 PM   #10 (permalink)
Intermediate EcoDriver
 
Mustang Dave's Avatar
 
Join Date: May 2009
Location: Northern Arizona - It's a DRY cold..
Posts: 671

Trigger - '07 Ford Mustang V6 Premium Coupe
Team Mustang
Sports Cars
90 day: 32.76 mpg (US)

Big Red (retired) - '89 Ford F-250 4wd Custom
90 day: 18.13 mpg (US)

Big Red II - '13 Ford F-150 FX4
Pickups
90 day: 19.61 mpg (US)
Thanks: 163
Thanked 129 Times in 102 Posts
Quote:
Originally Posted by buzz_42 View Post
Hey everyone!
I just got back from an 800+km trip.
I have the PLX Kiwi monitoring my mpg.
On the last leg of my journey, I decided to play around with my A/C.
I noticed that on a consistent flat road, when I turned on my a/c, my instantaneous mpg went down between 4 and 6 mpg. (depending on the road)
I am totally a newb. At tech school we were taught that a/c didn't take away power or mpg. This blew my mind!
Has anyone had a similar experience?
Also, I challenge you to find the flattest road you can and set your cruise and test it. A/C on and off. See what your mpg does.
Thanks for being patient if this is a total newb question!

- Buzz
I tried your challenge last Summer on a very slightly downhill section of road with my Mustang. Cruise control was set at 35 MPH. Scangauge indicated 80 MPG with A/C off. It dropped to 60 MPG when I turned on the A/C. 20 MPG/25% difference! Under those low load circumstances. I'll have to check the difference in GPH when I get a chance.

Living in the mountainous part of Arizona, I rarely use A/C except on road trips. When I need to use A/C, I set it on recirculating and "pulse & glide" the compressor.

__________________
Fuel economy is nice, but sometimes I just gotta put the spurs to my pony!



Quote:
Originally Posted by thatguitarguy View Post
Just 'cuz you can't do it, don't mean it can't be done...
Quote:
Originally Posted by elhigh View Post
The presence of traffic is the single most complicating factor of hypermiling. I know what I'm going to do, it's contending with whatever the hell all these other people are going to do that makes things hard.
  Reply With Quote
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com