Turning on headlights drop rpms, wth?
03-30-2012, 02:41 PM
#21
Registered User
Join Date: Feb 2008
Location: the great Maine wilderness
Posts: 2,048
Likes: 0
Received 4 Likes
on
4 Posts
The voltage stays the same because the alternator is maintaining it within a certain range. The reason that the engine slows down is because the generator is working harder and drawing the work from the fan belt.
The field windings are being sent more current which creates a stronger magnetic field that the armature must pass through creating more electricity for the battery and electrical system. The stronger magnetic field is harder for the armature to pass through creating more drag on the belt pulley. That drag is what pulls down the RPM's.
The field windings are being sent more current which creates a stronger magnetic field that the armature must pass through creating more electricity for the battery and electrical system. The stronger magnetic field is harder for the armature to pass through creating more drag on the belt pulley. That drag is what pulls down the RPM's.
03-30-2012, 04:17 PM
#23
... "idle up" features to boost idle speed when either of those devices are on at idle. You could probably wire up some relays to pick up that the head lights are on and have that bump up the idle via the A/C idle up VSV....I essentially do that on my '85. A/C is not hooked up but I left the dash switch and the idle-up VSV. When wheeling, especially at higher elevations at night, I'll just flip on the "A/C" which turns on the VSV and bumps the idle speed up.
03-31-2012, 11:19 AM
#24
Contributing Member
A larger alternator will not change the amount of work that the engine has to do to generate a given amount of electricity. A larger alternator will potentially produce more electricity. The things that will help your engine work less hard have already been suggested ... good connections, good grounds, larger wires, less accessories. 4crawler had a good solution to help your truck deal with added loads, (and he has forgotten more about electricity than I have ever even tried to understand).
Good stuff
http://www.4crawler.com/4x4/CheapTri...adlights.shtml
Good stuff
http://www.4crawler.com/4x4/CheapTri...adlights.shtml
Last edited by Buck87; 03-31-2012 at 11:37 AM.
03-31-2012, 11:31 AM
#25
Contributing Member
More good stuff:
I would start with cleaning all your grounds, battery cable and connections to/from the alt. Your gonna have to do it anyway with a higher amp alternator. Upgrading your battery cable to a higher gauge will help as well. The larger the gauge of wire the lower the voltage drop across them. The lower the voltage drop the lower amount of current that has to be supplied. = less strain on the alt.
I think this is why the headlight harness upgrade affected how much my alt affects the alt thus the draw on the engine and idle change.
FYI when I turn my heater on my idle drops from 950 to a little under 800.
I think this is why the headlight harness upgrade affected how much my alt affects the alt thus the draw on the engine and idle change.
FYI when I turn my heater on my idle drops from 950 to a little under 800.
Last edited by Buck87; 03-31-2012 at 11:37 AM.
03-31-2012, 12:17 PM
#26
Registered User
Join Date: Aug 2010
Location: miranda,ca
Posts: 92
Likes: 0
Received 0 Likes
on
0 Posts
i have looked through 4crawlers site through and through in the past few years all awesome info and have used alot of it. i think with out it there would be alot more shabby yotas running (or not running) around.
i did my head gasket a few months ago and everything is clean, grounds, connections and plugs alike. i think a good starting point for me, is to do a voltage drop between alt and batt, and at the same time see how many amps the alts actually putting out, says in the book with load at least 30a. 6 months ago i had to take it apart, somthing was stuck in between the brushes and shorting it out and going to overcharge. has worked ever since i cleaned it out, but i should check its output..sound right?
i did my head gasket a few months ago and everything is clean, grounds, connections and plugs alike. i think a good starting point for me, is to do a voltage drop between alt and batt, and at the same time see how many amps the alts actually putting out, says in the book with load at least 30a. 6 months ago i had to take it apart, somthing was stuck in between the brushes and shorting it out and going to overcharge. has worked ever since i cleaned it out, but i should check its output..sound right?
Thread
Thread Starter
Forum
Replies
Last Post
rushw
General Electrical & Lighting Related Topics
4
07-18-2015 01:46 PM
icentropy
86-95 Trucks & 4Runners
7
07-14-2015 10:23 AM
88runnergomas
86-95 Trucks & 4Runners
0
07-09-2015 01:12 PM
