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Discussion Starter #1
We have a 298 Massey tractor (pride and joy of our fleet) lol that we need to change the alternator. I meant to take a pic earlier but I forgot so will try my best to explain. It has a plug with three connections and one terminal off to the side by itself. The plug connections have one wire that goes to the dash light, then the other two have wire each that goes directly to the starter, which goes to the positive post on the battery. Now my first question is, should both those wires go to the same place (starter) or should one go somewhere else? Seems funny to run two separate wires to and from the same places. And my next question is, where should the terminal by itself be connected? It originally had a black wire connected to it that upon further investigation went to a connection in the wiring harness but went nowhere from there.


We have had this tractor for a few years now, and we got thinking we don't remember if it has actually ever charged since we got it. It doesn't do a lot, auger and mower and a few odd jobs, but sick of always boosting it. Last fall put a new alternator on, but it didn't have the terminal off by itself so tried it anyways. It was overcharging the battery so one day when we were drying grain, without thinking I unplugged the alternator and in doing so burned it out. (big arc)


We have decided to rewire the charging system because the last owner has pretty much butchered everything he touched. Sometimes easier to start from scratch, but not when you don't know how it should work!
 

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Well in the case of the oh so common GM delco "1 wire" alt the hot rudders special.
There are actually 3 connections.
One heavy stud terminal goes to the battery [usually via the starter to save wire]
Then the 2 spade connectors with lighter gauge wire are for the charging light and regulator sensor wire.
The indicator light is grounded through the alternator.
There are options for the regulator voltage sens line.
They're called a "1 wire" because the indicator light terminal does not need to be connected and the reg sens line can simply be looped to the heavy output terminal of the alternator.... now IDEALLY the reg sens wire should go directly to the battery, so the battery itself gets the correct voltage regardless of poor connections between it and the alternator.
Not sure if you have that alternator, they're quite common, but what it comes down to is typically you have a heavy charge current carrying wire direct to the battery.
A lighter gauge wire connected directly to the battery for voltage regulator.
And another lighter gauge wire that goes to ignition to "turn on" the alternator.
[The gm delco are "self exciting" so the "turn on" wire is omitted.

Hope I didnt confuse things [I feel like a confused myself there..]

And this is very typical unless you looking at a Chrysler that has a "generator" instead of a alternator.... which just means the regulator is remotely mounted....I doubt your massey woukd have that though. Screenshot_20190414-212729_Chrome_1555298866080.jpg
 

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With a self exciting reg you only need connect the output to battery. Depending on magnetic and or speed you may have to bump throttle to latch regulator
 

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With a self exciting reg you only need connect the output to battery. Depending on magnetic and or speed you may have to bump throttle to latch regulator
If your talking about the common delco alt, I sure you still need to loop the reg volt sens terminal to the Alt output terminal...... it's a short wire, but regulator still need to know voltage.


I just grabbed a quick pic last night [I did see some with, some without the diode] was not paying attention. What's the purpose of the diode anyway?
I have installed a delco without the diode and light actually just using that terminal to "turn on" the alt straight to ign......??
 

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Discussion Starter #8
Ok, here is what I have.


#1 this is the post I'm unsure of where it goes.
#2 this goes to the dash light
#3 and 4 both have their own wire that goes to the starter/battery, assume this is done to handle the high current?


So should #1 go to the ignition with power only with the key on, or can it go directly to the battery power?
 

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On a delco you only need an output wire hooked up. Nothing else. Yes you need a self energizing reg.(se) If you hook control wires up 1 goes to battery, and 1 to a keyed switch. If you hook both to a live connection you can drain battery. So that is were diode comes in. If you burp to 1/2 throttle a delco will latch with no control wiring. Been there, done that


https://alternatorparts.com/what-is-a-self-exciting-alternator.html
 

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1 VS 3 wire systems

Well in the case of the oh so common GM delco "1 wire" alt the hot rudders special.
There are actually 3 connections.
One heavy stud terminal goes to the battery [usually via the starter to save wire]
Then the 2 spade connectors with lighter gauge wire are for the charging light and regulator sensor wire.
The indicator light is grounded through the alternator.
There are options for the regulator voltage sens line.
They're called a "1 wire" because the indicator light terminal does not need to be connected and the reg sens line can simply be looped to the heavy output terminal of the alternator.... now IDEALLY the reg sens wire should go directly to the battery, so the battery itself gets the correct voltage regardless of poor connections between it and the alternator.
Not sure if you have that alternator, they're quite common, but what it comes down to is typically you have a heavy charge current carrying wire direct to the battery.
A lighter gauge wire connected directly to the battery for voltage regulator.
And another lighter gauge wire that goes to ignition to "turn on" the alternator.
[The gm delco are "self exciting" so the "turn on" wire is omitted.

Hope I didnt confuse things [I feel like a confused myself there..]

And this is very typical unless you looking at a Chrysler that has a "generator" instead of a alternator.... which just means the regulator is remotely mounted....I doubt your massey woukd have that though. View attachment 151311
The 3 wire alt isn't a 1 wire, there is a difference.
1 wire alternators suck, while a 3 wire can charge at idle.

alternators-1-vs-3-wire
 

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All you need is a se regulator. Got a dozen working just fine. Charges at an idle once locked in. No problems. I am out of here. I have not got high enough boots to keep going
 

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Looks like tswansons link has all that you need. Two wires are paralled to increase current capacity, the terminal (#2) above those is for indicating lamp and the one off by itself is not used. Perhaps it is for tach sensing as Anvil says.

You need to check with a voltmeter and see if it is charging. Verify connections from terminals 3&4 to battery are intact. If you aren't getting above battery voltage at half throttle then you need to look at the alternator.

Slim possibility that the circuit to terminal #2 needs to be intact so if bulb is burnt out or wire broken then there is no trickle of current to excite the field to start charging. Doubtful, but if no other explanation for what you see then maybe look into the possibility.
 

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I think what it comes down to is as long as the thing is spinning at a good rpm and there is power supplied to terminal #2 you should get over 12.6 volts at one or both of the big spade terminals.
 

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Discussion Starter #18
Thanks you guys, as usual you give good information. I put on the new alternator, left the one terminal alone, and everything is working and charging good. I got thinking that since we got the tractor, the dash light never worked but we changed it last fall and that was why it wasn't charging because it was an open circuit. So probably the original alternator and the one we put on actually worked, but with the light burnt out they wouldn't charge. The one we put on last fall I have a feeling wasn't the right one or wasn't working from new and was over charging. The joys of buying junk from Piston Ring, you never really know what you are getting, on more than one occasion we have bought stuff that didn't work from them, so when a guy is working on something not really sure of to begin with then getting parts from a place that you have your doubts if the parts are even working or not, can cause some grief! Thanks again guys!
 
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