Haynes Forums  

Go Back   Haynes Forums > Haynes Roadster Forums > Electrics
FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Display Modes
  #41  
Old 9th February 2010, 09:55 PM
Enoch Enoch is offline
Senior Member
 
Join Date: Nov 2009
Location: Near Boston, Lincolnshire
Posts: 788
Default

You have that the wrong way round Baz - the resistance of the bulb is the constant, it's the voltage that's the variable. As voltage increases and the resistance stays the same the current increases. Therefore higher engine speeds = higher voltage = higher current. always allow for this in calculating wire ratings. In the aircraft industry we used to do that, add 50 per cent then double it
Reply With Quote
  #42  
Old 9th February 2010, 10:10 PM
alga's Avatar
alga alga is offline
Senior Member
 
Join Date: Feb 2009
Location: Vilnius, Lithuania
Posts: 1,249
Default

Well, that's close to multiplying by pi, which is used when estimating software development ;-D
__________________
Albert
Haynes Roadster FAQ | Haynes Builder Locations
Gallery, build thread in Lithuanian / via Google Translate.
Reply With Quote
  #43  
Old 9th February 2010, 10:48 PM
AshG's Avatar
AshG AshG is offline
Super Moderator
 
Join Date: Jul 2008
Location: Rochester
Posts: 1,882
Default

i worked out the rating then doubled it on everything.
Reply With Quote
  #44  
Old 11th February 2010, 05:56 PM
baz-r baz-r is offline
Senior Member
 
Join Date: Nov 2009
Posts: 1,464
Default

Quote:
Originally Posted by Enoch View Post
You have that the wrong way round Baz - the resistance of the bulb is the constant, it's the voltage that's the variable
doh i know. i was just thinking in the wrong wavelength again
its the night shifts you know
Reply With Quote
  #45  
Old 11th February 2010, 06:18 PM
baz-r baz-r is offline
Senior Member
 
Join Date: Nov 2009
Posts: 1,464
Default

here's a quick calc linkey so no thinking is required

http://www.sengpielaudio.com/calculator-ohm.htm

55w bulb = 2.61 ohm at 12v

11.5v=4.41A
12v=4.58A
14v=5.34A

Last edited by baz-r : 11th February 2010 at 06:19 PM. Reason: typo
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

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT +1. The time now is 04:03 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.