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Unread 09-03-2009, 07:40 PM   #1
Kettles
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Alternator voltage output, what is the normal range?

OK, So I was wondering what is a normal range that the alternator should be putting out. I have a scangauge digital gauge thing, and one of the gauges I have it on is voltage. I always thought it ran a little low, because I have always been under the impression that normal output is like 14.2-14.4 volts. It usually ran 13.6-13.8, but today I noticed it hovering around 13.1. So my question is, where should it be?

Tomorrow if I remember I will clean the battery terminals again to see if that does anything.

Any advice? Am I just paranoid? (no doubt I am paranoid, I always am, but is it justified this time?)

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Originally Posted by speedbucket View Post
perfect depends on how far away you are when you look at it:D
Quote:
Originally Posted by Millermagic View Post
It's a 4.0 ... as long as there's something in the crank case that isn't coolant I'm sure it will still run forever.
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Unread 09-03-2009, 07:55 PM   #2
XJMuscle98
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13.1 seems a little low, nothing out of concern though.

You may want to consider doing the big 3 upgrade and see if it improves anything.

Temperature will also influence output.
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Unread 09-03-2009, 08:02 PM   #3
Kettles
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What is the "big 3 upgrade". I am no noob on here but thats a new one for me..
So where is the cuttoff for concern, below 13? below 12.5? If I know then I can keep my eye out for it.
AS far as outside air temperature this was about 75*, but it was really humid, maybe 70-80%. Engine temp was 206*, and air intake was running 116*. Got it to 3.5K rpm on an on ramp and it was 13.3 volts still btw.
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Quote:
Originally Posted by speedbucket View Post
perfect depends on how far away you are when you look at it:D
Quote:
Originally Posted by Millermagic View Post
It's a 4.0 ... as long as there's something in the crank case that isn't coolant I'm sure it will still run forever.
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Unread 09-03-2009, 08:12 PM   #4
XJMuscle98
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13.1 is low but good enough, once it starts getting below 13 I would draw concern imo.

Big 3 is upgrading to 1/0 awg wire from alternator to battery pos, battery neg to chassis/ground, engine to ground/chassis.

Current wires iirc are 8awg, so it allows more current to flow freely.
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1998 Jeep Cherokee 4.0L AW4/NP231 211k+

"Approximately 80 percent of our air pollution stems from hydrocarbons released by vegetation, so let's not go overboard in setting and enforcing tough emission standards from man-made sources."
Ronald Reagan

My goal is to have 20 lights around my XJ.

Currently: 10
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Unread 09-03-2009, 08:15 PM   #5
Kettles
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Oh, Never heard that called a big 3 upgrade. If It wern't for the fact I hate running wires I might do it. I terminated some 6awg wires on a trolling motor and it took everything I had on my biggest pliars to crimp in on good enough. seems like 1awg wire would be huge. That also is not a solution IMO. While I am sure the wires are kinda restrictive, and larger wires will help with crank times, that is an amperage thing. 22awg wire can handle 300volts, amperage is a measure of flow volume, voltage is pressure (using the good ol water through a pipe analogy). In this case It used to put out higher numbers and now it doesn't I highly doubt it is copper deterioration in the wires.
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"Dee", a Patriot Blue 2001 Cherokee Sport 4.0L High-Output Pictures Build Thread
The Rocket Sheep
"Live Free Or Die; Death Is Not The Worst of Evils." -General John Stark
Quote:
Originally Posted by speedbucket View Post
perfect depends on how far away you are when you look at it:D
Quote:
Originally Posted by Millermagic View Post
It's a 4.0 ... as long as there's something in the crank case that isn't coolant I'm sure it will still run forever.
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Unread 09-03-2009, 08:20 PM   #6
XJMuscle98
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0/1 actually.

which indicated the awg has one zero, which is 0 awg wire.

0/2 means two zeros so 00 awg

etc...

it's pretty big.

that blue wire is 0/1 wire

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"Approximately 80 percent of our air pollution stems from hydrocarbons released by vegetation, so let's not go overboard in setting and enforcing tough emission standards from man-made sources."
Ronald Reagan

My goal is to have 20 lights around my XJ.

Currently: 10
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Unread 09-03-2009, 08:25 PM   #7
Kettles
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You said 1/0 the first time, so I was assuming you meant 1 or 0 awg for 0awg I would just say 0, and for 00 i would say 00 Thats they way I have always heard it, and 0/1 is 2 charachters more so its not eve a shortcut (wheras 0/7 would make sense however).
Have you don the upgrade yourself? How long did it take you? I dont really ever plan on doing it, but if for w/e reason you can do it in 30 minutes or less I would. Only hicup would be the alternator to battery I can imagine. The others are open and straight forward. Isn't the engine to chassis ground the mesh wire at the back of the valve cover to the firewall? I assume the battery ground is just right at the battery there.
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"Dee", a Patriot Blue 2001 Cherokee Sport 4.0L High-Output Pictures Build Thread
The Rocket Sheep
"Live Free Or Die; Death Is Not The Worst of Evils." -General John Stark
Quote:
Originally Posted by speedbucket View Post
perfect depends on how far away you are when you look at it:D
Quote:
Originally Posted by Millermagic View Post
It's a 4.0 ... as long as there's something in the crank case that isn't coolant I'm sure it will still run forever.
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Unread 09-03-2009, 08:28 PM   #8
XJMuscle98
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Yea thats it.

once you have all the wires prepped and ready to go in it should be pretty quick and easy.

my bad I typed it wrong the first time.

haven't done it myself yet, but its good if you start getting lower output readings or dimming lights to help current flow.
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1998 Jeep Cherokee 4.0L AW4/NP231 211k+

"Approximately 80 percent of our air pollution stems from hydrocarbons released by vegetation, so let's not go overboard in setting and enforcing tough emission standards from man-made sources."
Ronald Reagan

My goal is to have 20 lights around my XJ.

Currently: 10
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Unread 09-03-2009, 08:44 PM   #9
Kettles
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2 things.
1: If anyone else has any input on the whole initial situation that would be great.

2: Is there a writeup for upgrading all the important wires to bigger ones. I don't like to do anything without a good full knowledge that I have everything I need before hand. I could buy a coil of 1 or 0awg wire and randomly start doing stuff but I dont roll that way. I would need new terminals, and whatever connectors I would need for the alternator. It also seems like new wires to the starter would be as usefull overall.
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"Dee", a Patriot Blue 2001 Cherokee Sport 4.0L High-Output Pictures Build Thread
The Rocket Sheep
"Live Free Or Die; Death Is Not The Worst of Evils." -General John Stark
Quote:
Originally Posted by speedbucket View Post
perfect depends on how far away you are when you look at it:D
Quote:
Originally Posted by Millermagic View Post
It's a 4.0 ... as long as there's something in the crank case that isn't coolant I'm sure it will still run forever.
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Unread 09-03-2009, 08:49 PM   #10
XJMuscle98
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How old is your alternator btw?
__________________
1998 Jeep Cherokee 4.0L AW4/NP231 211k+

"Approximately 80 percent of our air pollution stems from hydrocarbons released by vegetation, so let's not go overboard in setting and enforcing tough emission standards from man-made sources."
Ronald Reagan

My goal is to have 20 lights around my XJ.

Currently: 10
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Unread 09-03-2009, 08:52 PM   #11
Kettles
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Well the jeep is 8 yrs, so I would assume it is 8yrs old. I was happy to know I had a 124amp alternator factory, beats your 90amp. But if it fails then.. grrr.
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"Dee", a Patriot Blue 2001 Cherokee Sport 4.0L High-Output Pictures Build Thread
The Rocket Sheep
"Live Free Or Die; Death Is Not The Worst of Evils." -General John Stark
Quote:
Originally Posted by speedbucket View Post
perfect depends on how far away you are when you look at it:D
Quote:
Originally Posted by Millermagic View Post
It's a 4.0 ... as long as there's something in the crank case that isn't coolant I'm sure it will still run forever.
Kettles is offline   Reply With Quote Quick reply to this message
Unread 09-03-2009, 09:00 PM   #12
5-90
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Alternator output voltage should be min. .5VDC above the battery resting voltage, assuming you're not overdrawing the system.

Mains upgrades? The OEM mains wires are 8AWG, but I offer upgrade kits in 4AWG and 1AWG (and can get other sizes up to 0000AWG or "4/0AWG" by special order - but they're really not necessary! Even 1AWG is overkill...) if you like. That could get you everything you need right out of the box and ready to install. See the link in my sig, and hit me backchannel if you want to discuss it further.
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Unread 09-03-2009, 09:08 PM   #13
XJ Jay
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Quote:
Originally Posted by MattEagan View Post
Big 3 is upgrading to 1/0 awg wire from alternator to battery pos, battery neg to chassis/ground, engine to ground/chassis.
usaly the big 3 is done in what ever gauge the power wire for the alt is done, and in most cases 1/0 is OVER KILL! unless you have a HO alt and a serious stereo set up 4awg is more then fine. keep in mind that you may need 2 feet between the battery and the alt, 4awg can carry 200 plus amps of currant over the short of distance with out any degrade in performance. same applies for the grounds. if u need to run 15 feet or power wire to a amp that can draw 200 plus amps, then 1/0 is a must! other wise keep the cash in your pocket, as 1/0 typicaly is at least double the price of 4awg
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Unread 09-03-2009, 09:15 PM   #14
Kettles
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Hmm.. seems kind of expensive.. Not to mention I have no clue which one on the parts list I would need... lol.. anyway barring that stuff.. Back to my original question. Is 13.1v too low? I will do a check on my battery rest voltage tomorrow (again, If I remember) and Ill see what she reads running on the way to my dads house. I would rather not have to replace my alt.. or battery for that matter.. they are not cheap.

I could drop in a marine deepcycle battery I have in my dads garage and see if anything changes. I know its a good battery (only 2 months old) and its CCA is like 700 or something, which is more than my current battery. However it may not fit, it is quite large.

XJ Jay:
Yes I agree that 0awg is way overkill and never had any intention of replacing wires with ones that large, not to mention I never really intended to replace any wires....

Lets stay on the original topic.. this is my thread afterall.
__________________
_=====o000o
//__l_l_,\____\,____
l_--\_l__l_/--|lllll|
_.(o)_)__.(o)_)--o-)_)
"Dee", a Patriot Blue 2001 Cherokee Sport 4.0L High-Output Pictures Build Thread
The Rocket Sheep
"Live Free Or Die; Death Is Not The Worst of Evils." -General John Stark
Quote:
Originally Posted by speedbucket View Post
perfect depends on how far away you are when you look at it:D
Quote:
Originally Posted by Millermagic View Post
It's a 4.0 ... as long as there's something in the crank case that isn't coolant I'm sure it will still run forever.
Kettles is offline   Reply With Quote Quick reply to this message
Unread 09-03-2009, 10:02 PM   #15
5-90
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Quote:
Originally Posted by Kettles View Post
Hmm.. seems kind of expensive.. Not to mention I have no clue which one on the parts list I would need... lol.. anyway barring that stuff.. Back to my original question. Is 13.1v too low? I will do a check on my battery rest voltage tomorrow (again, If I remember) and Ill see what she reads running on the way to my dads house. I would rather not have to replace my alt.. or battery for that matter.. they are not cheap.
13.1VDC is probably about right - as I said, compare it to your battery's "resting" voltage and see what you've got to compare it to. As long as you can get a half-volt or so higher with the engine running than with the engine off, you should be fine.

And, don't trust the IP meter as an "absolute" reading - it's more a "relative state-of-charge" indicator than anything else (I do miss having an ammeter - it was actually more precise.) Anytime you get a reading at the IP that is in any way suspect, the first thing you should do is dig out your DMM and verify it!

You're probably not in line for a replacement - just check things out first.
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