Alternator went again

gary in neb. · Apr 24, 2017

so thought I had this alternator issue working on my white 2-135. went out disking yesterday and after about an hour the meter started bouncing around like it did in the past before the alt went out. did not have my digital with me so just unplugged it but did not seem hot. so before I condemn the alt i'm wondering if my gauge in the dash could be causing an issue? another thought, if I ran a new "hot" from the alt to the battery and disconnected the hot from the starter would it then isolate the alt to just the batteries?
Gary

Steve@Advance · Apr 24, 2017

This is really strange...

It shouldn't matter how the alternator is connected to the battery, to the starter solenoid is fine. Better there, that gets the connection away from the corrosive battery.

I suspect the volt meter is telling the truth, had it continued to spike voltage it would have eventually damaged the alternator. The gauge has nothing to do with the charging circuit, it just reports what it finds.

If I were going to rewire anything, it would be the wire from the battery post of the alternator to the #2 terminal of the alternator. If that connection is intermittent it will loose the reference voltage. You can buy that harness at the auto supply.

My only other thought would be a bad chassis ground, but even that shouldn't cause what you are having.

Another consideration would be a "one wire" alternator. That way there would be no question on the wiring.

Traditional Farmer · Apr 24, 2017

Advance Auto has a cheap little tester with a row of 6 lights to check charging,its about $12 handiest thing around I actually have a couple on tractors wired in that have no amp meter as they have a magnetic back.

gary in neb. · Apr 24, 2017

that wire is new. got a new pigtail thinking it had a bad connection. when I put this alternator on I ran a new wire (left the old one in place) from the "bat" of alternator to the solenoid. it's not actually the seloniod I guess is a relay that hooks to the solenoid as I could not find an end for a 10 gauge wire that fit a 3/4 bolt. the wire that goes to the "bat" and the relay are two separate wires but hooked at the same point at the selonoid. does that make sense?
I did run another ground from the alt to the block just to say I did it.
Gary

JimS · Apr 24, 2017

I had a similar problem with another vehicle. I ran a separate ground wire from the alternator directly to the frame. I haven't had an issue for years. Check your grounds and do not hesitate to add grounds; fairly cheap and easy to do.

gary in neb. · Apr 24, 2017

I have added one so far. direct from the alternator to the engine block.

Bob · Apr 24, 2017

1. What you are calling a "relay" may be a relay or a large circuit breaker. Either way, if it is arcing/a poor connection inside it could be destroying your alternators. How many terminals on it?

2. As I mentioned before, there needs to be an "idiot light", a resistor, or a diode in the circuit to the #1 "excite" terminal. If there isn't the alternator's diode trio or VR can be destroyed under certain circumstances. Have you checked for that?

gary in neb. · Apr 24, 2017

it's a relay that when engages would turn on the preheater for the engine. I tested the #1 wire and have resistance in it from the switch. thus the reason I did not add another resistor. however, at one point I had a resistor in it and the alt's still went bad. I could try another but when I metered the #1 terminal (it was last year so going on memory) it showed around 8 or 9 volt.
Gary

Janicholson · Apr 24, 2017

Put a condenser out of a spark ignition engine on the Each of the two Spade terminals (this should dampen spikes in the wiring and affect nothing else. Jim

INCase · Apr 24, 2017

Hello Gary,

any chance you could post pictures of the wires at the alternator and at the relay end that those same alt wires are connected to?

I think that might help us get you answers a lot faster without 20 questions and posts.

and
are all the bad alternators from the same store/brand?

Mark - IN. · Apr 24, 2017

Electrical problems can be tough to find, but if I can make a suggestion..."I ran a new wire (left the old one in place)"..., get rid of the old. If you replaced an original wire with an equal to or greater than gauge wire, get rid of the old. It may be a problem or it may become a problem. There are times when parallel can be an improvement and there are times when parallel can be a hindrance. If you replaced the old, take the old out of the equation and make a potential problem a non-problem.

Good luck.

Mark

JimS · Apr 24, 2017

I have an old Dodge pick up that was eating alternators. I went straight to the firewall. Don't hesitate to add another. It doesn't cost much and is cheap insurance.

gary in neb. · Apr 25, 2017

I will try and get some pics. alternators have come from different stores, some new some rebuilt so I've kinda ruled out bad alternators. i'm trying to find a FLIR camera I can borrow to try to find any "hot spots" that i'm missing.
Gary

Bob · Apr 25, 2017

Try a diode in the #1 circuit, AT THE ALTERNATOR. White banded CATHODE end goes to the #1 terminal.

I use 1N5408's, 3 Amps and 1000 PIV. If you can't find a cheap local source, I'll put one in an envelope and mail it you NC.

This will prevent any chance of the current the diode trio supplies to the regulator and rotating field from leaving the alternator thru the #1 terminal due to defective/improper wiring and killing the diode trio or regulator.

"when I metered the #1 terminal (it was last year so going on memory) it showed around 8 or 9 volt."

If that reading is correct with the engine running fast enough for the alternator to charge it would indicate an alternator that's already "sick" or something in the wiring loading the #1 terminal. You should "see" a voltage there VERY close to the voltage at the alternator's output stud.

The diagrams below show the effects of loading the #1 terminal.

<img src = "http://www.gondtc.com/~blweltin/Bob/DelcoSIA1A.gif">

<img src = "http://www.gondtc.com/~blweltin/Bob/DelcoSIB1A.gif">

gary in neb. · Apr 25, 2017

no one around here has a clue about that diode. does that just go "in line" with the wire?

Bob · Apr 26, 2017

(quoted from post at 14:46:37 04/25/17) no one around here has a clue about that diode. does that just go "in line" with the wire?

Note that in this example the #2 "sense" terminal is connected tp the output stud rather than to a point nearer to the battery (remote sensing) which is a better way.

Your alternator problem almost HAS to be either the #1 terminal is being loaded or there's an intermittent "open" in the wiring somewhere between the alternator's output stud and the battery.

If you can't easily find a diode locally, my offer to mail you one still stands.

[email protected]

gary in neb. · Apr 27, 2017

this is what I put on last night.

Alternator went again

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