CJ- ALT, 3 wire to 1 wire ??? - Off-Road Forums & Discussion Groups
Jeep-Short Wheelbase All discussion of short wheelbase Jeeps: CJ, TJ, YJ and JK

 
LinkBack Thread Tools Display Modes
post #1 of (permalink) Old 02-28-2005, 08:00 PM Thread Starter
Keyboard Implanted
 
Smokngun's Avatar
 
Join Date: Sep 1999
Location: Palmyra, WI
Posts: 2,209
Thanks: 0
Thanked 0 Times in 0 Posts
 
CJ- ALT, 3 wire to 1 wire ???

Hi All, The alternator has been dead on My '83 CJ-7 for a while now and I got a new one wire alternator for it (GM style) about two weeks ago. I'm just getting around to putting it in and need some help.

Nowhere in the instructions for the new alternator does it say what to do with the two leftover wires (in one plug). Do I tape them up? Do I run a jumper across them? I don't want to cook anything so I'm askin' you guys! I feel really dumb, I should know this.

Thanks! Mike.
Smokngun is offline  
Sponsored Links
Advertisement
 
post #2 of (permalink) Old 02-28-2005, 11:12 PM
Way Outta Control
 
Join Date: Sep 1999
Location: usa
Posts: 10,815
Thanks: 0
Thanked 1 Time in 1 Post
 
Re: CJ- ALT, 3 wire to 1 wire ???

The reason they call it a one wire is it needs no other connections. Just tape them up or remove them.

But then, nobody told you the one wire alternators won't keep the battery fully charged, and you won't have the dash idiot light working anymore.

And you'll probably find it doesn't charge when you first start it and at low speeds like idle. Lights will flicker and dim at low speeds - but without the light you won't notice.

Notice some of the websites that sell them also want you to get a smaller pulley for the alternator to help with the last problems - just spins it faster.

Same troubles with the "cheat" method - of running the sense wire to the output.

It' not logical to me - you get less for more $$.
RRich is offline  
post #3 of (permalink) Old 03-01-2005, 06:35 PM Thread Starter
Keyboard Implanted
 
Smokngun's Avatar
 
Join Date: Sep 1999
Location: Palmyra, WI
Posts: 2,209
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: CJ- ALT, 3 wire to 1 wire ???

Thanks Rich, I didn't buy it with the intention of having a one wire alternator. I was under the inpression that it was "Bolt In" meaning ALL connections were the same as stock. I don't have an idiot light, I've got a volt meter, so that's not an issue. Why would it have low voltage output at idle/slow speeds? The tag claims 80 amps at idle and 140 at 2500 rpm...I know amps are not volts, I'm just a bit confused. Thanks for the help! [img]images/graemlins/smile.gif[/img]
Smokngun is offline  
Sponsored Links
Advertisement
 
post #4 of (permalink) Old 03-01-2005, 07:41 PM
Way Outta Control
 
Join Date: Sep 1999
Location: usa
Posts: 10,815
Thanks: 0
Thanked 1 Time in 1 Post
 
Re: CJ- ALT, 3 wire to 1 wire ???

The 2 wires on the side that you don't have on those.
One runs the "alt" light. But it also provides the field current to get it started charging.
The one wire's either don't use anything to get it started, or use a resister so high it stops charging at idle. That's why they recommend you use a smaller pulley so it spins faster, never goes as slow as it would if it used the correct pulley.

And the other small terminal - it's the "sense" wire - it monitors the state of charge of the battery - hooked directly to the battery. The "one wire's" just run that wire internally to the output of the alternator instead. The result is it's monitoring itself, not what it's supposed to be charging. It will cause the battery to never fully charge. Verify that by checking the battery with a hydrometer - you'll see.

I like to equate it to asking a politician if he's honest, or a car thief, a bank robber, or most anyone in prison. They'll all tell you they are honest - while their fingers are in your pocket. You can't ask them to self monitor, just like you cannot ask the alternator if it's charging the battery properly.


They work, just not like they could or should.
RRich is offline  
post #5 of (permalink) Old 03-01-2005, 09:34 PM
Official Historian
 
WILL's Avatar
 
Join Date: Sep 1999
Location: Hot Springs, AR
Posts: 8,339
Thanks: 1
Thanked 5 Times in 5 Posts
 
Re: CJ- ALT, 3 wire to 1 wire ???

I have a question about the sense wire on my setup. I am using a solenoid to starter cable as my connection between the alternator and a marine terminal on the top post. I have the sense wire hooked to the back of the alternator. I don't see what difference it makes if it is sensing the voltage at the alternator or the other end of that massive cable.
WILL is offline  
post #6 of (permalink) Old 03-01-2005, 09:57 PM
Mud in my Veins
 
Caver Dave's Avatar
 
Join Date: Apr 2000
Location: Winston-Salem, NC
Posts: 5,512
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: CJ- ALT, 3 wire to 1 wire ???

Just remember the thousands just like me...

Pulled a used Delco off the shelf (unknown origin or output), spent 15 minutes adjusting spacers to mount it, 1 minute connecting it, and the past 4 years wondering when/if it will ever break/fail to keep the RedTop up enough to run the lights and winch! [img]images/graemlins/tongue.gif[/img]

Hell, it's one of the few things I *DON'T* worry about [img]images/graemlins/grin.gif[/img]
Caver Dave is offline  
post #7 of (permalink) Old 03-02-2005, 10:31 AM
Way Outta Control
 
Join Date: Sep 1999
Location: usa
Posts: 10,815
Thanks: 0
Thanked 1 Time in 1 Post
 
Re: CJ- ALT, 3 wire to 1 wire ???

Whenever there's current running through a conductor there's a voltage drop across that cable. The end opposite from the alternator will be a tad lower than at the alternator.

A battery that's only partially charged has very near the same voltage as one that's fully charged - within thousandths of a volt, even the slightly lower voltage at the battery end "seen" by the regulator results in the regular "thinking" the battery needs more, so it keeps on charging it. (Remember the energy being pumped into the battery is being converted to chemical energy, not stored voltage. That's why the voltage is so close.)

If it's "seeing" something other than the battery, like the alternator output, it gets "tricked" into thinking the battery's fully charged and lowers the current.
It eventually drops down to the point where the only output current it's providing is what the rest of the system demands, lights, ignition etc. The battery only gets "what's left over."


Remember too that a battery can only accept about 30 Amps to charge, more than that takes way excessive charging voltage and will kill the battery. When you gut up into the 16+ volt range it's possible to overcharge and burn it.

Keeping a battery undercharged shortens it's life and can't provide as much energy that you think it can. Like when operating a winch, you want as much power as you can.

Try it - Discharge the battery part way - like crank it a long time, or leave the lights on for awhile.

Attach the sense line to the alternator output - the cheat method - like the one wire's.
Run it till you think it's charged. Check the specific gravity of the battery - remember the reading.
Now change the sense line direct to the battery.
Start it again. Hear the alternator groaning again? It's charging that "fully charged battery."
After it's charged again, check the specific gravity again. Higher now. Battery is happier.

Believe it or not - The energy is actually stored as weight - the battery actually gets heavier! Not enough to notice, very slight, but enough to measure with a precision scale - try it! The higher specific gravity proves that - the higher the number, the heavier the solution is.

When a battery charges up, the electrical energy is stored in it chemically. That's why they say never add acid to a battery that's low - just water. If you did, the acid content would be too strong and the plates would erode real fast, and the chemical reaction would not work as well.
The sulfuric "acid" you buy at the parts house is dilute acid already, not full strength sulfuric, already has the right mixture of acid to water.

Since the energy is converted to chemical energy, the voltage is very close comparing a partially discharged vs. a fully charged one. The regulator makes it's determination as to charge or not charge by that very slight voltge difference.

Even a very discharged battery still has 2.1 volts per cell, but very little energy left.

Try it!
RRich is offline  
post #8 of (permalink) Old 03-02-2005, 12:35 PM
Can't Get Enough
 
Join Date: Mar 2000
Location: So. Jersey
Posts: 1,003
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: CJ- ALT, 3 wire to 1 wire ???

Quick quiz..........What happens if you hook your battery up backwards??????? ..........The headlights cast shadows and your stereo listens..... [img]images/graemlins/grin.gif[/img] [img]images/graemlins/grin.gif[/img] [img]images/graemlins/grin.gif[/img]
JimmyZ is offline  
post #9 of (permalink) Old 03-02-2005, 03:00 PM
Way Outta Control
 
Join Date: Sep 1999
Location: usa
Posts: 10,815
Thanks: 0
Thanked 1 Time in 1 Post
 
Re: CJ- ALT, 3 wire to 1 wire ???

He He -- some things don't mind -- they are the ones that aren't smoking.
RRich is offline  
post #10 of (permalink) Old 03-02-2005, 04:06 PM
 
Join Date: Nov 2000
Posts: 2,687
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: CJ- ALT, 3 wire to 1 wire ???

[ QUOTE ]
...The result is it's monitoring itself, not what it's supposed to be charging. It will cause the battery to never fully charge. Verify that by checking the battery with a hydrometer - you'll see.

I like to equate it to asking a politician if he's honest, or a car thief, a bank robber, or most anyone in prison. They'll all tell you they are honest - while their fingers are in your pocket. You can't ask them to self monitor, just like you cannot ask the alternator if it's charging the battery properly.

[/ QUOTE ]

How about this, its like putting the thermostat in the furnace room. It might be the same temperature as the rest of the building, but likely not.
TiminMb is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Off-Road Forums & Discussion Groups 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 for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may not post new threads
You may not 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