Voltmeter only reading 12 volts - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Electrical
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 08-06-2010, 07:27 PM
Registered User
 
Last photo:
Join Date: Oct 2006
Location: pennsylvania
Posts: 1,091
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Voltmeter only reading 12 volts

I have a chevy one wire alternator--it always read 14 volts---today it dropped to 12--should I replace alternator?

all wires correct and tight

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 08-07-2010, 08:06 AM
sqzbox's Avatar
My pipes are my music
 
Last photo:
Join Date: Sep 2009
Location: indiana
Age: 64
Posts: 2,938
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Anything less that 14 V is shot. Might want to get it tested at the local part's store just to be sure. AZ and advance will test it for free. That will eliminate the gauge being faulty. At 12V it won't be long before the battery will give out stranding you on the road or parking lot away from home. Right now it appears your running off battery voltage only.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 08-07-2010, 08:34 AM
Registered User
 
Last photo:
Join Date: Oct 2006
Location: pennsylvania
Posts: 1,091
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I checked it with voltmeter at alternator and its reading 13-14 volts. NOW GET THIS!!! I had a B&M Megashifter that had a back-up light switch on it--this past winter I changed to a Gennie shifter which did not have the back-up light switch---so I taped the wires up and thought hell I never use the back-up lights anyway. But just yesterday I thought since I live in Pa I should have a way to turn them on because if the lights are on the car they must be functional. I put them on a toggle switch . Tonite the wife and I went out for a fish sandwich and somehow she (or her big purse must have hit the toggle (yeh its on her side of the car) because when I walked around the car I noticed the lights were on---turned them off and everything OK now---can't believe them 2 bulbs would pull that much juice---think I'll dissconect them again!
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 08-07-2010, 08:52 AM
sqzbox's Avatar
My pipes are my music
 
Last photo:
Join Date: Sep 2009
Location: indiana
Age: 64
Posts: 2,938
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
LOL. Never leave controls within reach of a woman! Just move the switch.
I have a toggle switch on my 4x4 with a red light in-line and the auxilary light's mounted backwards on the roll bar. Never had working back-up light's since I bought the truck. The auxilary light's work better than any back up's like having headlight's on the rear. Works great when 4 wheelin' in the dark.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 08-07-2010, 07:52 PM
Registered User
 
Last photo:
Join Date: Oct 2006
Location: pennsylvania
Posts: 1,091
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I know what U R saying---raced flat fenderer Jeeps with BIG motors for years---and plenty of trail riding after dark
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 08-08-2010, 12:17 PM
T-bucket23's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Engine basic condition - how to check Last photo:
Join Date: Aug 2005
Location: Massachusetts
Age: 57
Posts: 5,204
Wiki Edits: 26

Thanks: 7
Thanked 116 Times in 101 Posts
If you put the backup lights back on does your voltage drop to 12. In a healthy electrical system a pair of backup lights will not effect the alternator output.
What is the output voltage with the headlights on.

I am betting your regulator int the 1 wire is failing.
__________________
Artificial Intelligence is no match for Natural Stupidity



Chet
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 08-08-2010, 12:53 PM
Rickracer's Avatar
ASE Master Tech, Fabricator
 
Last wiki edit: Taurus 2-speed fan control wiring diagram Last photo:
Join Date: Jan 2010
Location: Kissimmee, Florida
Age: 55
Posts: 937
Wiki Edits: 8

Thanks: 0
Thanked 3 Times in 3 Posts
Could be a poor ground to the Voltmeter too,
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 08-08-2010, 03:08 PM
Registered User
 
Last photo:
Join Date: Oct 2006
Location: pennsylvania
Posts: 1,091
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
It stays right around 14 with headlights AND elec fan running---They are both run thru relays,but backup lights arent---wonder if thats why????
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 08-09-2010, 07:23 AM
T-bucket23's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Engine basic condition - how to check Last photo:
Join Date: Aug 2005
Location: Massachusetts
Age: 57
Posts: 5,204
Wiki Edits: 26

Thanks: 7
Thanked 116 Times in 101 Posts
Quote:
Originally Posted by yragat
It stays right around 14 with headlights AND elec fan running---They are both run thru relays,but backup lights arent---wonder if thats why????
They draw the same if they are run straight or through a relay. The relay just takes the big load off the switch.
Did you try turning them back on to see if the problem comes back. I am still not convinced that the backup lights are adding enough load to pull alternator voltage down to 12 volts.
Makes no sense
__________________
Artificial Intelligence is no match for Natural Stupidity



Chet
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 08-09-2010, 08:15 AM
Rickracer's Avatar
ASE Master Tech, Fabricator
 
Last wiki edit: Taurus 2-speed fan control wiring diagram Last photo:
Join Date: Jan 2010
Location: Kissimmee, Florida
Age: 55
Posts: 937
Wiki Edits: 8

Thanks: 0
Thanked 3 Times in 3 Posts
Quote:
Originally Posted by T-bucket23
... I am still not convinced that the backup lights are adding enough load to pull alternator voltage down to 12 volts.
Makes no sense
I agree, hence the comment about a poor ground. When I run into stuff that doesn't make any sense, about 98.9% of the time, it's a result of a poor ground.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 08-09-2010, 10:07 AM
Registered User
 
Last photo:
Join Date: Oct 2006
Location: pennsylvania
Posts: 1,091
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Ran it all day yesterday---14 volts came home turned on backup lights just fol the hell of it and sure enough--right down to 12---weird huh
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 08-09-2010, 07:28 PM
Rickracer's Avatar
ASE Master Tech, Fabricator
 
Last wiki edit: Taurus 2-speed fan control wiring diagram Last photo:
Join Date: Jan 2010
Location: Kissimmee, Florida
Age: 55
Posts: 937
Wiki Edits: 8

Thanks: 0
Thanked 3 Times in 3 Posts
Did you check the output at the alternator while the dash gauge was reading that low? I would........
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 08-09-2010, 08:04 PM
Registered User
 
Last photo:
Join Date: Oct 2006
Location: pennsylvania
Posts: 1,091
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by Rickracer
Did you check the output at the alternator while the dash gauge was reading that low? I would........

No I didn't---I will tomorrow
Reply With Quote Quick reply to this message

Recent Electrical posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
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 for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Cruise Control Compatibility with LED's? cboy Electrical 44 10-01-2010 12:08 PM
A true 12 bolt? pittbull7934 Transmission - Rearend 16 07-01-2009 08:34 AM
help please on a 67-69 rearend code PE MusclecarBob Transmission - Rearend 10 06-16-2009 12:35 PM
6 volts or 12 cantspel Electrical 6 12-04-2004 04:08 PM
Converting Light System to 12 volts JohnTN Electrical 2 12-04-2004 01:15 AM


All times are GMT -6. The time now is 09:34 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.