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Unread 08-02-2009, 10:00 AM   #1
cj5jeff
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1981 CJ5 
 
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Low Voltage - Alternator not charging battery

I just installed a new alternator after my old one appeared to not be charging. I did not check the alternator before buying a new one as it was old. My votlage guage shows about 11 volts which drops to about 10 when the lights or anything else is turned on. I totally rewired the Jeep with a Painless harness during my recent frame off resto. The motor is a 360 with a Delco alternator. All compnents of the ignition system are new inluding the ignition module. Anyone have any ideas as to what might be causing the low voltage and battery not to be charging?

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Unread 08-02-2009, 11:22 AM   #2
CO64CJ5
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Which Delco alternator?
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Unread 08-02-2009, 05:26 PM   #3
JeepHammer
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LOW VOLTAGE complaints are usually bad volt gauges, or bad connections to the gauge.

If I'm reading this correctly, you have a problme with low voltage,
AND,
AFTER you installed the painless harness you had battery drain?

Anyway, I'd say take the alternator to be tested.
If the rectifier diodes are shot, it will charge about half way, and it will drain after shutoff.

All the discount places bench test for free, but I'd get two or three opinions before I made my mind up,
Some people don't know how to run the machines correctly.

You need to FULLY charge the battery.
Low current over a long period of time.
Check electrolyte levels before charging.

Once fully charged, you can LOAD TEST the battery at any of the discount places, they all have free testing with a full on load tester.

To find a 'Load' (electrical term for a 'Drain'),
Remove the NEGATIVE battery cable from the battery.
Makes sure there is NOTHING hooked up to the negative battery post.

Then get yourself one of the inexpensive Multi-Meters.
You can get them anywhere from Wally-World to Radio Shack to Harbor Freight.
(From $5 to $500, but the one you are looking for will be around $15 or $20)

Turn the dial on the Multi-Meter to DC VOLTS, and you want to say under 20 volts.

Hook up one test lead wire to the battery post via a clamp of some sort,
(Rubber bands or hose clamp work VERY well)

And the other test lead wire to the negative battery cable clamp.

Now you will read ALL loads being drawn by the vehicle.

Start by disconnecting the two wire plug from the alternator.
If the load vanishes (or mostly vanishes) you found the problme.

If not,
Pull the large wire off the back of the alternator.
Again, if the load vanishes, you found the problme (alternator).

Make sure some PO or nit-wit didn't connect anything but the positive battery cable to the battery positive terminal...
If they did, UNHOOK IT...

And then remove the smaller wires, One at a time, from the starter relay (except for the large battery cable, you have to keep the system connected while testing).

If the large starter cable on the other side of the starter relay makes the load disappear, then the starter relay is bad.

If removing either of the two smaller terminal wires makes the load vanish, then you have a bad starter relay.

If you remove the smaller wire from the BATTERY CABLE side of the starter relay, and the load vanishes,
You need to make longer test leads for your multi-meter.
That wire is the supply to the fuse block, and you are going to hook it back up,
Then move your multi-meter under the dash where you can see it,
And start pulling fuses one at a time to find the circuit where the load is hiding.

Pull fuses until you find the circuit that has the load,
Then you will need to get a wiring diagram, and hunt down what appliance is causing the load.

One thing I would start with,
Make sure your interior lights aren't turned on.
Even if you DON'T HAVE interior lights, your headlight switch is wired for that circuit, and you can have the wire that is supposed to power up the interior lights grounded out...

Another common phantom load is a bad cigarette lighter... They like to draw once they fall apart internally.
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Unread 08-02-2009, 07:15 PM   #4
cj5jeff
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Huge thanks. Given that everything is new and I wired the entire Jeep myself, I am sure that it is a bad connection that I caused somewhere. I will go through your steps and find it. Again, thanks for the help. This forum is great.
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Unread 08-29-2009, 08:59 PM   #5
cj5jeff
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Great help. Thanks. However, I still have not been able to track down the problem. My meter reads 20 on the 25DCV setting. It is off the charts on the 5 setting. The load goes away when I remove the wire on the battery side of the starter solenoid which from the above I understand to mean that there is a short somewhere in the fuse block. I have removed every fuse and the load still does not go away. I removed the plug on the steering column, the four wheel and reverse light indicators. I removed the wire in the engine compartment that goes to the heater. Everything else I think is fused. I am stumped.

What am I missing?!?!
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Unread 08-29-2009, 09:31 PM   #6
jatepper
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Sorry I cannot contribute. I'm having either the same or a very similar problem right now. If I get more replies with the info I am looking for on my thread I will share. Good luck.
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Unread 08-29-2009, 09:44 PM   #7
cj5jeff
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I should add that I have a new battery and alternator. I should also add that when I bought the alternator there were two options for the 360, one that had 63 amps and one that had 78 amps. I bought the lower amperage battery and don't think this is the issue but I may be wrong. Everything in the Jeep is new including all of the guages. No dirty connections, etc. New Painless wiring harness. Because I did everything myself I am certain it is something small that I did wrong but just cannot trace it down.

Jatepper - if you find a fix please send me a PM
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Unread 08-29-2009, 11:32 PM   #8
carnuck
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Check the plug on the alt to be sure you don't have it backwards! It'll have this exact issue if it is. Oh! And make sure you have a ground wire from the battery negative to the body or the grounds for the lights, etc will have to pass through the engine bearings, trans, driveshaft, leaf springs to get back to the front!
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Unread 08-30-2009, 08:10 AM   #9
JeepHammer
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My 'Guess' is either lack of ground to the alternator, which you should run a dedicated ground to the alternator on a 24+ year old vehicle,

OR,
The fusible link that connects the 10 Ga. 'Red' wire to the back of the alternator has given up and is intermittent.

Since it starts charging, then drops off...
That probably means the resistor wire (#1 terminal on the two wire plug) is still intact and giving 'Excite' current to get charging started...

If it were me,
I would start by 'tugging' LIGHTLY on the fusible link where it attaches to the starter solenoid, battery cable side...
This will probably tell you if the fusible link has seen better days if the links 'Stretches' or seems corroded inside the insulation.

And I would supply the alternator with a dedicated ground by installing a 10 Gauge ground directly to the alternator housing.

I would also check the connections to the 'Sense' terminal,
The larger wire in the two wire plug.
You can do this by simply 'Looping' it around back of the alternator and connecting it to the 'BAT' terminal on the back of the alternator.

Last edited by JeepHammer; 08-30-2009 at 08:21 AM..
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Unread 08-30-2009, 08:54 AM   #10
cj5jeff
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I will give this a try. Thanks for the help.
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Unread 09-06-2009, 08:23 PM   #11
mmi
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Quote:
Originally Posted by JeepHammer View Post
My 'Guess' is either lack of ground to the alternator, which you should run a dedicated ground to the alternator on a 24+ year old vehicle,

OR,
The fusible link that connects the 10 Ga. 'Red' wire to the back of the alternator has given up and is intermittent.

Since it starts charging, then drops off...
That probably means the resistor wire (#1 terminal on the two wire plug) is still intact and giving 'Excite' current to get charging started...

If it were me,
I would start by 'tugging' LIGHTLY on the fusible link where it attaches to the starter solenoid, battery cable side...
This will probably tell you if the fusible link has seen better days if the links 'Stretches' or seems corroded inside the insulation.

And I would supply the alternator with a dedicated ground by installing a 10 Gauge ground directly to the alternator housing.

I would also check the connections to the 'Sense' terminal,
The larger wire in the two wire plug.
You can do this by simply 'Looping' it around back of the alternator and connecting it to the 'BAT' terminal on the back of the alternator.
I'm reading and following this with the same problem.

Dumb question: What do you mean by the 'battery cable side' of the solinoid? I have a positive red cable connected to the solinoid nearest the battery, and a large black negative cable on the opposite side of the solinoid.

I unhooked the ned cable from the battery as you said, with the DVM set up that you described. It reads 11.4 volts between the neg post and the neg cable clamp (compared to 12.6 volts between the battery posts)

I unhooked the red cable (to the solinoid from the pos battery post) and the volts drop from 11.4 and go to zero. Is it a bad solinoid?

I have a new battery and a new alternator, but the volts never move up above 12.6 with the engine running.

Everything starts fine, so I assumed the solinoid (starter relay?) was fine, but as it runs, the battery gets no charge from the new alternator.
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Unread 09-06-2009, 08:43 PM   #12
jatepper
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If you have AC, make sure the AC is off when checking the voltage. The AC sucks a lot of power, but the system should still be charging your battery.

Quote:
Originally Posted by mmi View Post
I'm reading and following this with the same problem.

Dumb question: What do you mean by the 'battery cable side' of the solinoid? I have a positive red cable connected to the solinoid nearest the battery, and a large black negative cable on the opposite side of the solinoid.
Yes, he means the red cable from the positive terminal of the battery to the starter. WHere the red connects is the "battery cable side"
__________________
1985 Jeep CJ-7
Automatic-258 I6- Detroit lockers front/rear - Superior 1-piece axles, Ramsey Pro 9000 Winch, Quick Disconnects, 33 BFG AT's, 4.10 gears, Howell TBI, DUI HEI Ignition, Ground Pounder Rear Bumper / Tire Carrier Combo, Handen Fab integrated winch plate front bumper w/hoop, ORF weld-in front sport cage.

USMC 1999-2004 Semper Fi!

Hood Hi-Lift Jack Mounts for CJ/YJ/TJ/JK

Torchmate CNC Plasma Table Build / Projects

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Unread 09-06-2009, 09:21 PM   #13
mmi
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Quote:
Originally Posted by jatepper View Post
If you have AC, make sure the AC is off when checking the voltage. The AC sucks a lot of power, but the system should still be charging your battery.



Yes, he means the red cable from the positive terminal of the battery to the starter. WHere the red connects is the "battery cable side"
Ok, I think I've been testing it wrong - he means keep the primary thick red cable connected, but remove the smaller wires one by one. no wonder the volts dropped to zero when I unhooked the large red cable from the solinoid.

I wonder if starting with volts of about 11.4 means I have that neg load test set up correctly? Is that about how it should read if it's messed up and the alternator is not charging the battery?
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Unread 12-20-2009, 07:15 AM   #14
cj5jeff
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I tried everything JeepHammer reccomended and still can't identify the problem. Here is what I know:
1) My meter pegs at the 5 setting when it is connected as JeepHammer suggests. I have to use 25 to get the needle to where I can get a reading.
2) Volts drop to zero only when remove the small wire on the battery side of the starter relay.
3) I have removed each of the fuses in turn and the voltage does not go away.
4) All of the guages work and are all new.
5) Turning the lights on or off does not make voltage go away.
6) All new wiring by Painless so I can't blame something stupid on PO - I am the nitwit that has done something wrong.
7) I have nothing else connected to the battery.
8) The alternator is brand new and the alternator I removed appeared to be doing the same thing. The test JeepHammer suggests inidcates it is not the alternator.
9) The battery is new and fully charged with a charger.
10) The Jeep goes totally dead after sitting for a few days.
11) I get higher voltage on a fully charged battery but it very quickly drops to about 12 - 12.5 volts after driving for a bit.
12) I installed a new DUI ignition and nothing changed regarding the voltage problem.
13) Engine is a 360.
14) One other clue is that the wiper motor fuse blew some time back; not sure if it was related to the problem. It had a 15 amp fuse that I replaced with a 20 amp fuse and now seems fine.
15) The lights are always bright and do not indicate low amperage.

Bottom line - I have power going to ground somwhere - if it is not in the dash, not in the engine and not in the lights where else should I look and how do you troubleshoot this? JeepHammer, if it was not so close to Christmas and so cold here in Utah I would offer to send you a plane ticket to get here! This is getting thes best of me. Thanks in advance for any help you can give me.
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Unread 12-20-2009, 10:54 AM   #15
JeepHammer
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I'm booked until the 11th of January.

FIRST...

What I suggest you do is to take a close look at your alternator.

Take it to the local discount stores (more than one) and have it 'Tested'.
The reason for more than one is, it's free, and the guys behind the tester aren't always trained as well as the should be.

Get a consensus if the alternator is working correctly or not, that would be the starting point.
-------------------------------

SECONDLY,
Dash gauges LIE!

Take your voltage readings AT THE BATTERY.
Use the next setting above 12 volts on the scale.
(IE, 20 volts if you show that setting, if not, 200 volts)

Your battery voltage will DROP when you crank the engine, then it will come back up over a couple of minutes after you start the engine and the alternator does it's job recharging the battery.

If you DO NOT see this happening, then your charging system has 'Issues'...

--------------------------------------

THIRD,

"Painless" harnesses ARE NOT PAIN-LESS.
"Pain in the Azz" would be a better name for them.

---------------------------------------

HOOKUP...


You will need THREE Wires to the alternator and they must be wired correctly...

#1 will be the 'Excite' terminal.
It's labeled as #'1' or 'R' on the back of the alternator case at the REGULATOR PLUG.
It will be the SMALLER of the two wires, usually 'Brown' in the harness.

IT will need to be 'HOT' when the ignition switch is in the 'Run' position.
It SHOULD NOT be 'Hot' when the key switch is in the 'Accessory' position.

This wire can be spliced from the module 'Red' or 'Run' wire, but will need a 'Resistor' or 'Diode' at the plug in for the alternator.

The value of that resistor or diode will depend on which Delco alternator you have.
The Jeep CJ alternator is a Delco 10 SI and the upgraded FSJ alternator will be a Delco 12-SI that has the same requirements for a resistor or diode.
That would be about 10 to 15 Ohms resistance, same as the factory resistor wire (Brown Wire) to the factory alternator plug.

A diode can be substituted for the resistor in the SI series of alternators with no ill effects.

If you have gone over to a Delco 130 or 140 CS alternator, then more resistance is required in that excite line. Somewhere between 75 and 150 Ohms.
--------------------------------------




--------------------------------------

#2 Will be the 'Sense' or 'Sample' wire.
It will be labeled as #'2' or 'F' on the back of the alternator at the regulator plug.

You have some options for this wire, but the easiest way is to loop it around to the back of the alternator and connect it to the 'BAT' terminal on the back.

This line simply takes a Sample of the line voltage going to the battery.
If it drops below about 13 volts, this line tells the regulator to make more current,
When the line voltage exceeds 14.5 volts, this is the line that tells the regulator to start limiting current.
---------------------------

'BAT' Terminal On the back of the alternator.
This is the primary 'Charge' wire to the battery.

Since this wire is exposed to danger from grounding, it must have a SAFETY FUSE connected to it.

Factory uses a 'Fusible Link', a special blend of silver, nickel, chrome, lead, ect. that will burn through and save the alternator, and keep a fire from starting if the primary 'BAT' wire gets grounded.
I normally use a 12 Ga. fusible link with 10 Ga. alternator 'Bat' wire.
You can find fusible links at any discount store display with the regular fuses, but they will usually be on the bottom row...

DO NOT RUN YOUR SYSTEM WITHOUT A FUSIBLE LINK!





The 'BAT' terminal wire will run from the alternator back to the FUSIBLE LINK, which should be connected to the 'BATTERY CABLE' side of the starter relay ('solenoid'),

This keeps the fusible link at the 'Head' of the 'Bat' wire and will protect the entire length of the 'Bat' wire,
And it is mounted far enough away from the battery it will not cause an explosion of the battery gasses if the fusible link burns violently.

With these three connections your charging system should keep somewhere between 13.5 & 14.5 volts at the battery (once the battery is charged up from starting the vehicle).
----------------------------------

I also recommend you add a DEDICATED 10 GA. GROUND WIRE TO THE ALTERNATOR CASE FROM THE BATTERY CONNECTION POINT.

With DC current, you MUST complete the circuit!
Without proper 'Grounding', or circuit completion, the alternator WILL NOT work at peak efficiency.

--------------------------------------------

Here is a VERY SIMPLE diagram for wiring your Delco SI series alternator...




Notice the part numbers for the diode in the legend of this diagram?
This works WITH, or can be used alone (without) resistor wire in place...

Also notice the diode has a 'Stripe', and that stripe faces the alternator plug?

This is CRITICAL since the diode won't work if installed with the stripe facing the harness instead of the alternator!

If you have a working resistor wire (many have fallen apart down through the years) then the diode probably won't be necessary.

When I use a diode instead of, .... or inline with a resistor wire,
This is how the replacment plug looks when I'm ready to install it on the alternator/wiring harness,

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