Volts way out of line? - Chevelle Tech
Electrical & Wiring Troubleshooting electrical problems.

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
post #1 of 30 (permalink) Old May 4th, 03, 3:44 PM Thread Starter
Lifetime Premium Member
Bill
 
Join Date: Jul 2000
Location: cols ohio/43123
Posts: 3,261
Post

Something I did not notice before or something keeps changing? Tested volts again with everthing on the volts went way past 16 volts when I gave it some gas.Changed wire ,ran from the # 2 pin on the alt to the thru firewall hook up and volts still past16 volts giving it some rpms.Turned everything back on except the head lights it went to 15.8 volts.Turn headlights back on it goes past 16 volts.Turn everthing off it reads 15.2
Last week it read 15.2 with everthing on.Whats
going on??


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


Sold May 09

540 BIG BLOCK
10.10 @ 130 ON MOTOR
9.47 @139 ON 175 HIT
driver is offline  
Sponsored Links
Advertisement
 
post #2 of 30 (permalink) Old May 4th, 03, 8:32 PM Thread Starter
Lifetime Premium Member
Bill
 
Join Date: Jul 2000
Location: cols ohio/43123
Posts: 3,261
Post

John,Peter what do you think?


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


Sold May 09

540 BIG BLOCK
10.10 @ 130 ON MOTOR
9.47 @139 ON 175 HIT
driver is offline  
post #3 of 30 (permalink) Old May 4th, 03, 11:49 PM
Senior Tech Team
 
Join Date: Dec 1999
Location: Canada
Posts: 1,413
Post

That's strange. Did you meaure that voltage at the connection for the #2 wire?

It sounds to me that either the alternator isn't regulating the voltage or there is a bad ground.

You need to have a decent sized wire connecting to the battery, body, engine and frame all together. You need a main power wire from the battery to frame and frame to engine to provide the return for the starter. Then, run something like a #8 from the engine, battery or frame to the body. Remeber, the grounds need to be sized as heavy as the positive wires.

Peter
Peter F. is offline  
 
post #4 of 30 (permalink) Old May 5th, 03, 9:49 AM Thread Starter
Lifetime Premium Member
Bill
 
Join Date: Jul 2000
Location: cols ohio/43123
Posts: 3,261
Post

This car is grounded to death.It has a large cable
the same size of the main cable running to the firewall thru connection.One running to the cage,one running to the frame,one large running from the block to the frame and one running from the block to the firewall.Maybe I need to pull the alt and have it rechecked?Crazy thing!Thanks,Driver


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


Sold May 09

540 BIG BLOCK
10.10 @ 130 ON MOTOR
9.47 @139 ON 175 HIT
driver is offline  
post #5 of 30 (permalink) Old May 5th, 03, 10:56 AM
 
Join Date: Feb 2000
Posts: 7,762
Post

Ever hook up that lead to terminal #1? It has a purpose.
John_Muha is offline  
post #6 of 30 (permalink) Old May 5th, 03, 2:36 PM Thread Starter
Lifetime Premium Member
Bill
 
Join Date: Jul 2000
Location: cols ohio/43123
Posts: 3,261
Post

Yes, I did. But it doesn't make any difference concerning the reading of the volts. At least it doesn't change when I hook it up or disconnect it. The only thing I noticed when it is hooked up is the generator light comes on.
Thanks, driver


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


Sold May 09

540 BIG BLOCK
10.10 @ 130 ON MOTOR
9.47 @139 ON 175 HIT
driver is offline  
post #7 of 30 (permalink) Old May 5th, 03, 5:38 PM
 
Join Date: Feb 2000
Posts: 7,762
Post

Quote:
Originally posted by driver:
Yes, I did. But it doesn't make any difference concerning the reading of the volts. At least it doesn't change when I hook it up or disconnect it. The only thing I noticed when it is hooked up is the generator light comes on.
Thanks, driver
Interesting. When the alternator is running the GEN light should go off. If it's not going off with the engine running try:
Engine off, unplug the connector. Turn the key on and measure the lead that goes to #1. That wire should have 12 volts. (That 12 volts comes from the ignition switch).
John_Muha is offline  
post #8 of 30 (permalink) Old May 5th, 03, 7:06 PM Thread Starter
Lifetime Premium Member
Bill
 
Join Date: Jul 2000
Location: cols ohio/43123
Posts: 3,261
Post

This car is driving me crazy.Took off alt and went to the shop that built it.Put it under a heavy load tested fine,14.2 under a load.Put it on a 40% load for 30 mins and it tested fine(14.2)
Tested amps 90.Took it back home hooked it back up
and ran the jumper off B+ alt - #2 plug in plus ran the brown wire to the #1 plug in.Alt 14.2
firewall cable 13.6 plug in #1 13.8.Turned everthing on fuse box 12 alt 13.2 firewall cable 12 the fuse box was really a little less than 12.
Volt gauge inside of car was reading below 12.I don't get it.The man that built the alt said what John had said about the #1 plug-in.I just don't know where to go with this thing next??Thanks


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


Sold May 09

540 BIG BLOCK
10.10 @ 130 ON MOTOR
9.47 @139 ON 175 HIT
driver is offline  
post #9 of 30 (permalink) Old May 5th, 03, 9:12 PM
 
Join Date: Feb 2000
Posts: 7,762
Post

Belive Peter suggested moving the #2 wire off the B+ terminal and tying it someplace else. Think he suggested the horn relay. Tried that or am I simply forgetting stuff again?
John_Muha is offline  
post #10 of 30 (permalink) Old May 6th, 03, 12:33 AM
Senior Tech Team
 
Join Date: Dec 1999
Location: Canada
Posts: 1,413
Post

I should have asked where you were reading the high voltage? When you tied the #2 wire to the horn relay the stock fuse panel and wiring should not have read over 14.2V. But, the alternator wire and the battery could have been higher.

In all cases, the firewall connector and battery should read at pretty much the same voltage. At these current levels you won't get hardly any voltage drop across that #1 guage wire.

Does the wire to the firewall connector also run the starter or is there a seperate starter wire?

I think your best bet is to connect the #2 alternator wire to the firewall connector. Try that and tell us what you get voltage wise. The firewall connector is the main power connection point for the car so that is the place where you want to regulate the voltage.

When I look at the voltages you just posted you're getting 13.2V at the alternator and 12V at the firewall connector. So, the wiring from the alternator to the trunk mounted battery and back drops 1.2V. Connecting the alternator #2 wire to the firewall connector will compensate for this by increasing the output voltage.

What rpm is required for the alternator to produce full output current? You should be able to get that from the rebuilder. What pulley ratio are you running from crank to alternator? The wiring method will only make the alternator produce what it's capable of.

Peter
Peter F. is offline  
post #11 of 30 (permalink) Old May 6th, 03, 11:55 AM
 
Join Date: Feb 2000
Posts: 7,762
Post

So far, I agree with Peter but maybe I am not seeing something else.
*A question about the wires on your horn relay.*
Do you still have the original large power wire that went to the bulkhead connector tied there? This wire originally supplied the original fuse block in the car. Thinking along with Peter's suggestion about moving the sense line to the firewall connector, the original fuse block line may also need to be moved there. (Keep thinking that the problem may be related to having 2 large loads separated from each other)
If I'm seeing things right this is an unusual set-up. Not that it can't be made to work.
John_Muha is offline  
post #12 of 30 (permalink) Old May 6th, 03, 10:15 PM Thread Starter
Lifetime Premium Member
Bill
 
Join Date: Jul 2000
Location: cols ohio/43123
Posts: 3,261
Post

I'll recheck everything again in the morning and let you know.When I was getting 16+ volts at the alt I tried it both ways on the # 2 pin.Off horn relay and off the firewall but nothing changed.I'll get more detailed with results next time.I checked so much I can't remember everthing.
Driver


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


Sold May 09

540 BIG BLOCK
10.10 @ 130 ON MOTOR
9.47 @139 ON 175 HIT
driver is offline  
post #13 of 30 (permalink) Old May 7th, 03, 12:25 AM
Senior Tech Team
 
Join Date: Dec 1999
Location: Canada
Posts: 1,413
Post

If you measured 16V at the same place the #2 wire from the alternator was connected you MUST either have an alternator problem or a bad wiring problem (ground or power wiring). I just can't think of any other reason this won't work.

The #2 wire is the sensing wire for the alternator. That is the terminal that the internal regulator measures to adjust it's output. So, the voltage where the wire is connected should not go above the 14.2V that the regulator operates at. With a heavy load, you can draw the voltage down but it should never go above 14.2V at the point where that wire is connected.

What size of wire were you using when you connected the #2 wire to the other locations. The stock wiring harnesses I see have what looks like a 10 or 12 gauge wire connecting that terminal up. It must be heavy for a reason since the factory wouldn't waste the heavy wire for no reason.

Another thing to try is to move the meter -ve lead around when you're measuring the voltage. For example, when measuring at the same spot try putting the -ve wire on the body, frame, engine, alternator case, etc. The voltage should always measure the same or the ground is bad. Similarily, you can put the meter leads at each end of a wire to measure the voltage drop across it. Remember, every wire will have some voltage drop but with the wire sizes you have the voltage drops should be very small, likely in the 0.1 to 0.2 volt drop range as a maximum.

I think you need to eliminate a possible bad wiring connection. Crank it up with all the loads and look for a hot spot in the wiring because that'll indicate a poor connection.

If you are sure about the wiring then ask the alternator rebuilder about the #2 terminal being used as the sense wire and connecting it to another spot besides the bat post on the alternator. Maybe he did something funny in the rebuilding (what I wouldn't know). Maybe you need to take the car to him and confirm the wiring method you're using with him.

I can tell you one thing. If you want to run it with the #2 terminal connected to the Bat post on the alternator you will likely have to increase the wire size of the alternator to battery run and still live with a low voltage in the engine compartment. As an example, 8awg is 0.67 ohms of resistance per 1000 feet. So, 0.67 divided by 1000 is 0.00067 ohms per foot. 25 feet would be 0.01675 ohms. Times that by 90A and you get a 1.5V drop. Scary, huh? So, if you have 14.2V at the Bat post on the alternator the best you can get is 12.7V at the battery. You then get less after the wiring run back to the front of the car. By moving the sensing wire, the alternator will produce 15.7V at the Bat terminal so that you get 14.2 at the battery.

So you know, 1awg is 0.126 ohms per 1000 feet and 25 feet would have a 0.28V drop at 90A. So connecting the #2 terminal to the firewall end of the #1 wire should not result is a voltage at the battery much over about 14.5V.

Peter
Peter F. is offline  
post #14 of 30 (permalink) Old May 7th, 03, 10:22 AM Thread Starter
Lifetime Premium Member
Bill
 
Join Date: Jul 2000
Location: cols ohio/43123
Posts: 3,261
Post

One thing the alt builder said about the #1pin didn't make any sense to me.I noticed when he was testing it that he had a wire running to the #1 pin which I ask him what was the reason for it.He
said to energize the alt off of a key switch.The way I took it was with-out a hot wire going to the #1pin the alt wasn't charging? I thought thats was what the jumper wire running off the b+ alt to the #2 pin was for? This alt went way past the 16 volts range but it didn't do that the 1st time I did the test.I had thought about getting a alt from a buddy to see if it makes a difference.
I'll get busy today and try many different ways and this time write it down.Thanks for all your help on this on going problem.Driver


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


Sold May 09

540 BIG BLOCK
10.10 @ 130 ON MOTOR
9.47 @139 ON 175 HIT
driver is offline  
post #15 of 30 (permalink) Old May 7th, 03, 11:45 AM
 
Join Date: Feb 2000
Posts: 7,762
Post

Pin 1 is the field and requires an excitation voltage to the alternator. If an alternator is new or has sat for a period of time it won't start without the excitation voltage from the key switch. The idiot light was added in there as a "extra feature" and is not the reason for the wire.
Pin 2 is the remote sense line. It's the line that controls what the alternator puts out. If everything is close together, tying it to the back of the alternator works. If things are spread out, moving it away from the alternator and closer to the heavy loads works better. The sense line then measures that remote point and raises the voltage slightly out of the alternator.
Unless I misread things you have 2 points that draw a heavy load while normally there is only 1 point. The 2 points are
1, The original fuse block
2, The new firewall connector.
Moving the remote sense wire, from Pin 2, to the firewall connector should help. As the big power items come on, the remote sense wire will see the voltage drop on the firewall connector. The alternator B+ voltage will then go up to compensate for the heavy load. In other words, we don't care about the voltage on alternator B+. We only care about the voltage on the firewall connector.
That should take care of the problem with the firewall connector. Since you have a very large wire from the firewall connector to the battery, the voltage should almost be identical. This should keep the battery charged.
The next problem that may occur is the voltage to the old fuse block. I believe you still have this tied to the horn relay. After you have the system controlling the firewall connector, this point needs to be measured. If this point is too low, the wire to the fuse block, in the harness, should be moved to the firewall connector. However, one thing at a time.
John_Muha is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Chevelle Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address. Note, you will be sent a confirmation request to this address.

Email Address:
OR

Log-in









Old Thread Warning
This Thread is more than 6038 days old. It is very likely that it does not need any further discussion and thus bumping it serves no purpose.
If you still feel it is necessary to make a new reply, you can still do so though.

Thread Tools Search this Thread
Show Printable Version Show Printable Version
Email this Page Email this Page
Search this Thread:

Advanced Search
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may 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 On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome