A/C power usage - Fuelly Forums

Click here to see important news regarding the aCar App

Reply
 
Thread Tools Display Modes
 
Old 07-07-2006, 10:17 AM   #1
Registered Member
 
Join Date: Oct 2005
Posts: 682
Country: United States
Smile A/C power usage

I used the Scangage to determine the HP used by the A/C. With the A/C off, the Scangage read 0.4 gph. With it on, the Scangage oscillated between 0.5 and 0.6. Call it 0.6.

So assuming 20% efficiency for the diesel at idle:

Fuel rate at idle, A/C off
0.4gphFuel rate at idle, A/C on0.6gphA/C fuel usage0.2gph23000BTU/hrFuel conversion efficiency20%Combustion energy to HP4600BTU/hrEnergy conversion factor2545BTU/hr/hpMechanical HP1.8



This is at idle. I don't know if it varies much with RPM.
__________________

__________________
Capitalism: The cream rises. Socialism: The scum rises.
Sludgy is offline   Reply With Quote
Old 07-07-2006, 12:58 PM   #2
Registered Member
 
GasSavers_civicminded's Avatar
 
Join Date: May 2006
Posts: 71
I would assume that it would be pretty much a constant for when the compressor was running. Movement (and subsequent airflow over the condensor) would cause it not to run as much, but while it's on, I see no reason why it would vary.

My $.02
__________________

__________________
www.onetruth.com
www.sohchonda.com

GasSavers_civicminded is offline   Reply With Quote
Old 07-07-2006, 02:17 PM   #3
Registered Member
 
psyshack's Avatar
 
Join Date: May 2006
Posts: 443
Country: United States
It will use more at higher rpm. No butt dyno can feel 2 hp. But the butt dyno can feel it going down the road under load. Just turn a A/C on and off pulling a very slight grade.

Or as I called it in my Festive the turbo button. Turning the A/C off was like a shot from a bottle of NOZ.
__________________
09 HCHII, w/Navi
07 Mazda3 S Touring, 5MT
Mild Hypermiler or Mad Man?
psyshack is offline   Reply With Quote
Old 07-07-2006, 03:51 PM   #4
Registered Member
 
GasSavers_civicminded's Avatar
 
Join Date: May 2006
Posts: 71
Good point psyshack -

I guess I was thinking more of average loss rather than instantaneous. If the pump is spinning faster, it won't be on as long to reach required pressure. Therefore over time the average would be the same, or at least close to it (as we all know that spinning faster will loose some efficiency to friction).

And I LOVE the "turbo button" analogy - any of you guys remember Knight Rider? "Turbo Boost KITT!!"
__________________
www.onetruth.com
www.sohchonda.com

GasSavers_civicminded is offline   Reply With Quote
Old 07-08-2006, 03:09 AM   #5
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
What gets me is going down hill with no gas - darn cpu adds fuel when I kick in the AC and it doesn't need to. Next trick will be the blower fan kill switch so the AC runs at highway speed without the fan running - just using the natural air flow - should save some juice that way - can't recirculate however.
JanGeo 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
Looks like the price you entered for a litre of gas is unrealistic. winstona Fuelly Web Support and Community News 6 05-12-2013 10:26 AM
A side project I am working on... DTMAce General Fuel Topics 3 04-29-2010 02:21 PM
The Drive Smart Challenge mathowie General Fuel Topics 0 08-15-2008 08:55 AM
Diesels are very efficent at idle? philmcneal Diesels 36 04-05-2007 06:25 PM
Recommendations for a tire gauge Compaq888 General Fuel Topics 10 04-21-2006 02:18 AM

» Fuelly iOS Apps
No Threads to Display.
Powered by vBadvanced CMPS v3.2.3


All times are GMT -8. The time now is 10:30 PM.


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