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Clay-All-Over

Posted 12/2/2009 19:10 (#947097)
Subject: Alternator Overcharging problem

Eastern Ontario

After blowing a few alternators and batteries, I decided to try and figure out the reason of why this was happening.

John Deere 4440
Delco Remi 10SI alternator
two 12 volt batteries ( 12 V system )

These are the new components I have installed today.

2 new batteries ( charged )
new alternator
made all new wiring related to batteries and alternator except the resistance wire kit which was installed a few years ago.
also installed a ground cable going from alternator to -tive pole on battery.

Some test results:

engine off / key switch off / voltage at batteries = 12.5V
engine off / key switch off / voltage at alternator bat terminal = 12.5V
engine off / key switch off / voltage at alternator no.2 terminal = 12.5V
engine off / key switch off / voltage at alternator no.1 terminal = 0 V
engine off/ key switch ON / voltage at bat and no.2 terminals =12.5V
engine off / key switch ON / volatage at no.1 terminal = 10.7V ( book says it should be between 2 and 9V )
engine running / voltage at bat terminal in the 14V range
engine running / voltage at terminal no.1 in the 12 V range

Going by the book, if terminal no.1 is either below or above 2 to 9 V, then alternator is the problem.

I've tried two alternators and both are the same. I don't think it's the alternator. I'm almost certain.

I'm thinking the problem is between the no.1 terminal and the key switch.

Question: Why was the original resistance wire replaced with the resistance wire kit? Could it be the problem? Could it be the key switch itself? I'm lost. The book doesn't take me in this direction.

Should I be looking someplace else?

Alternator pic is not mine, just borrowed from Google;-)

Edited by Clay-All-Over 12/2/2009 19:13

(Delco10SI.jpg)

(Resistance Kit JD.jpg)

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Delco10SI.jpg (50KB - 1123 downloads)
Attachments

Resistance Kit JD.jpg (69KB - 1169 downloads)

Gerald J.

Posted 12/2/2009 19:31 (#947136 - in reply to #947097)
Subject: Re: Alternator Overcharging problem

14.2 volts is the correct charging voltage. That's not overcharging.

15 or 16 volts is overcharging and comes from a shorted voltage regulator.

The rectifier is for a gas tractor with the alternator initial excitation coming from the ignition terminal on the switch. Without the diode the 10SI will backfeed the ignition and prevent stopping the tractor with the ignition switch.

Gerald J.

Jon Hagen

Posted 12/2/2009 20:03 (#947180 - in reply to #947136)
Subject: Re: Alternator Overcharging problem

Hagen Brothers farms,Goodrich ND

What voltage are you reading at the battery with the engine running ? Ideal is 14.2 volts, but most Delco 10 - 12 SI alternators for automotive use are set to make 14.6. a bit more than necessary for a tractor that works long hours, but not really harmful. Delco regulators set for 14.2 V are readily avalible for the same price.

You need full system voltage to the #2 wire, as this is where the internal voltage regulator "senses" system voltage and tells the alternator to charge hard enough to maintain 14.2-14.6 volts.
The only function of the #1 wire is to excite the alternator which starts it charging. Anything between 2 and 11V is fine as. long as the alternator excites at a reasonable rpm.
The ONLY reason there is a resistor in the #1 wire is to protect the diode trio and regulator from a high amp backfeed through the #1 wire if another accessory (such as the ignition coil in a gas engine.) is connected to that same ignition switch terminal. It also keeps the alternator from trying to charge the battery by backfeeding through the #1 wire if the heavy BAT wire should go open circuit.
On a gas engine, a diode to block backfeed in the #1 wire, or a resistor to limit backfeed to a level below what will power the ignition system and also limits backfeed to a level below what will damage the diode trio and regulator.

Lil' Hoss

Posted 12/2/2009 20:02 (#947177 - in reply to #947097)
Subject: Re: Alternator Overcharging problem

NESD

Anything over 15.5 volts is considered overcharging so your 14 volt range is fine, the resistance wire kit was installed because the original wire deteriorated to the point that the insulation was gone, this is very common. Over the years I have found many mistakes in the tech manuals and I suspect the voltage test at terminal 1 with the engine off/key off is one of them, the voltage should be zero.

Clay-All-Over

Posted 12/2/2009 21:14 (#947331 - in reply to #947097)
Subject: RE: Alternator Overcharging problem

Eastern Ontario

OK. So lets say that my 14.? V is fine. What would cause a battery to cook so much that no acid is left in it at all at the end of the day. This happened to two batteries within a week. These were not old batteries. Maybe a year or two max.

Also, while running, the needle on the dash would go so far to the right that it almost and sometimes goes into the red. I turn on all lights to keep the charge lower in hopes to save the batteries.

Now that is not normal.

Shouldn't the alternator charge and then not charge? I mean, not charge ALL the time?

Edited by Clay-All-Over 12/2/2009 21:21

marlinpain

Posted 12/2/2009 21:23 (#947346 - in reply to #947331)
Subject: Re: Alternator Overcharging problem

45 miles south spingfield il.

do you replace batteries in pairs?

Jon Hagen

Posted 12/2/2009 21:44 (#947408 - in reply to #947346)
Subject: Re: Alternator Overcharging problem

Hagen Brothers farms,Goodrich ND

I have a Delco 12 SI alternator on my 4450 with the 14.6 volt regulator in it. This is a bit higher than the ideal 14.2V and runs the voltmeter about 3/8 inch from the red. To lower the system voltage just a bit, I connected the regulator plugs #2 wire directly to the big BAT stud on the alternator rear. This makes the regulator sense system voltage right at the alternator instead of back deep in the wiring harness. Moving that #2 wire to the alternator bat connection, prevents the system from increasing the voltage to compensate for voltage drop in the wiring harness. This gives me much closer to the ideal 14.2 volts at the battery when I have cab blower and / or lights on, which is a good thing for the batteries.
You might try this with your 4440, as it eliminates any possible fault in your harness #2 sense wire and lowers the system voltage closer to the ideal 14.2 volts. Put a 1/4 inch ring terminal on the regulator plugs #2 sense wire and attach it to the BAT stud. Tape up the original harness sense wire to prevent possible shorts and you should be good to go. This is common practice on generator to alternator conversions.

(Delco alternator wiring and 12V conversion.jpg)

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Delco alternator wiring and 12V conversion.jpg (28KB - 1351 downloads)

Clay-All-Over

Posted 12/2/2009 22:04 (#947447 - in reply to #947408)
Subject: Re: Alternator Overcharging problem

Eastern Ontario

I will try to connect the no.2 terminal to the bat terminal on the alternator tomorrow and see if that changes anything. As you said, that would eliminate andy doubt in the no.2 circuit. But I would think with my new wiring that this is not the case.

Jon Hagen

Posted 12/2/2009 21:28 (#947363 - in reply to #947331)
Subject: Re: Alternator Overcharging problem

Hagen Brothers farms,Goodrich ND

a charge rate that burys the voltmeter or cooks the batteries dry in a few days would indicate over voltage, well above 15 volts. Over voltage can be from a #2 sense wire with a bad connection in the harness or corroded plug at the alternator, sending a false low voltage signal to the internal regulator, causing the alternator to send actual system voltage above 15 volts. A defective regulator will also cause over voltage, but not likely with two alternators. I would suspect a poor connection in the #2 sense circuit.

The alternator should not charge then not charge, it should maintain a set constant voltage, close to the ideal 14.2 volts.

A battery with one shorted cell is in effect a 10 volt battery. the alternator is set up to charge a 12V battery which takes a minimum of 13.5 volts, 14 .2 V is ideal. A perfect 12V charging system connected to a 10V battery, (a 12V with one shorted cell is a 10 v battery) will boil that 10v battery dry while trying to do the impossible job of charging a 10v battery to 12 V.

Clay-All-Over

Posted 12/2/2009 21:48 (#947415 - in reply to #947363)
Subject: Re: Alternator Overcharging problem

Eastern Ontario

Maybe that was the problem. A bad connection in the no.2 line. I've changed that one front to back and actually ran that line to the starter terminal instead of the firewall solenoid. Some people just put the two lines together at the bat connection on the alternator which I think is not right.

So a bad line may have worked the alternator too hard and boiled a battery and killed a cell. Then make the alternator work even harder.

I did not change the batteries in pairs, so maybe they were both no good anymore.

I'm gonna ignore that 10.7V reading and see how long these batteries will last me this time.

With all new wiring, I think this should be OK now. I hope.

Thanks for clearing that up for me guys.

CATGUY

Posted 12/2/2009 21:48 (#947414 - in reply to #947331)
Subject: RE: Alternator Overcharging problem

Iowa

On your original post; your 2nd paragraph states: the new components I installed TODAY.

Did you already correct your problem with your new wiring?

How does your dash voltage gauge act now, after your new components and wiring?

Then again, maybe, you are just trying to back-track a little, to figure out what happened to those earlier batteries.(or I am mis-reading your information)

Clay-All-Over

Posted 12/2/2009 21:53 (#947425 - in reply to #947414)
Subject: RE: Alternator Overcharging problem

Eastern Ontario

The readings I posted and the position of the guage is what I got after all the new stuff was put in. The only odd thing I have now is the high voltage in no.1 terminal with ignition ON and the gauge going too far to the right when running the tractor.

Jon Hagen

Posted 12/2/2009 22:04 (#947449 - in reply to #947425)
Subject: RE: Alternator Overcharging problem

Hagen Brothers farms,Goodrich ND

Clay-All-Over - 12/3/2009 20:53

The readings I posted and the position of the guage is what I got after all the new stuff was put in. The only odd thing I have now is the high voltage in no.1 terminal with ignition ON and the gauge going too far to the right when running the tractor.

The voltage drop on the #1 wire depends on how much load the alternator field circuit puts on it with the engine off and alternator not charging. Should be in the 5-10 volt range. With the engine running and alternator charging, there is no load in the #1 resistor wire and as much as 14 volts is normal.

I would check the accuracy of the in dash voltmeter with a good analog voltmeter right at the battery posts. If it is a bit higher than you like, moving that #2 sense wire to a connection at the alternator BAT terminal will usuall lower the voltage at the battery as much as 1/2 volt. It worked well on my 4450.

Jon Hagen

Posted 12/2/2009 23:05 (#947573 - in reply to #947449)
Subject: Re: Alternator Overcharging problem

Hagen Brothers farms,Goodrich ND

One other thing I forgot to mention, it takes higher voltage to charge a cold battery, less for a hot one.. For that reason, voltage regulators are temperature compensating to correctly charge a hot or cold battery. The regulator will automatically raise the alternator voltage a bit in cold weather and lower it a bit in very hot weather, to adjust for the needs of the battery. At 0 F, it is normal for a Delco alternator to charge at 15 volts. Don't mistake this automatic temperature compensation for a system fault.

Edited by Jon Hagen 12/2/2009 23:22

RickB

Posted 12/3/2009 05:51 (#947777 - in reply to #947097)
Subject: RE: Alternator Overcharging problem

Lincoln County. NC

It may be worthwhile to go back and do all the voltage tests after the tractor is worked and at operating temps.

Greywolf

Posted 12/3/2009 07:15 (#947810 - in reply to #947097)
Subject: Not to hijack but a somewhat related condition

Aberdeen MS

On my old Chevy single ax, the alternator will not self excite right after start up. Not sure which alternator it is for sure, but a '75 era 65 series with a 366.

After driving for up to 4 or 5 miles it will charge normally and offer no problems. Just takes a long time to excite, longer under load than without load it seems. An example being driving after dark or during the day, lights and no lights.

Just a curiosity more than anything else as to the "why". It's done the most hauling this year than others, it got a grand total of maybe 200 miles this year, but that's stretching it.

Battery is fully charged with no bad cells and battery connections cleaned at the start of the season.

Jon Hagen

Posted 12/3/2009 10:05 (#948027 - in reply to #947810)
Subject: RE: Not to hijack but a somewhat related condition

Hagen Brothers farms,Goodrich ND

Greywolf - 12/4/2009 06:15

On my old Chevy single ax, the alternator will not self excite right after start up. Not sure which alternator it is for sure, but a '75 era 65 series with a 366.

After driving for up to 4 or 5 miles it will charge normally and offer no problems. Just takes a long time to excite, longer under load than without load it seems. An example being driving after dark or during the day, lights and no lights.

Just a curiosity more than anything else as to the "why". It's done the most hauling this year than others, it got a grand total of maybe 200 miles this year, but that's stretching it.

Battery is fully charged with no bad cells and battery connections cleaned at the start of the season.

Make sure the alt belt is tight. possible low excite current from a fault in the #1 circuit. R&R the regulator plug in the alt(they love to corrode there).
possibly an out of spec regulator with too high a "kick in" voltage. One or more blown diodes in the diode trio. Worn,oily, sticky brushes.

Greywolf

Posted 12/3/2009 17:05 (#948446 - in reply to #948027)
Subject: Re: Alternator Overcharging problem

Aberdeen MS

Thanks Jon. Like I mentioned, more of a curiosity thing than anything else. It charges normally when it does excite and starts up.

Will be on the "to do" list next year when it's warmer out. It's hibernating right now for a few months.

Clay-All-Over

Posted 12/3/2009 12:43 (#948192 - in reply to #947097)
Subject: Update

Eastern Ontario

Not much has changed.

Did some tests this morning.

Checked both batteries for Volts and amps. Theyare OK

Tractor running / voltage at alt output is 14.47 V

Tractor running / voltage at battery is 14.45V

Used a little jumper cable from term. 2 to bat. on alternator with exact same results

Tractor stopped /voltage at battery is 13.01V

tractor stopped / voltage at term.1 is 11.25V

tractor stopped / voltage at term. 2 is 13.01 V

Everything seems normal except for the 11.25V at term.1.

Voltage guage is still on right hand side just before the red. I let the tractor run for at least 15 min.

I don't see what else I could do. I will assume that this is fixed and watch the alternator and batteries closely when the tractor goes back to work.

Thanks for everyones help.

ronm

Posted 12/3/2009 21:09 (#948848 - in reply to #948192)
Subject: RE: Update

Fruita CO

Sounds to me like you're good to go...

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