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JD 4020 24v alternator wiring


 
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quake
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PostPosted: Sun Jan 24, 2010 8:03 pm    Post subject: JD 4020 24v alternator wiring Reply to specific post Reply with quote

A friend of mine replaced the gererator with a one wire 24v alternator. It's only charging one battery. What I can't understand is if the alternator in grounded and only one battery is grounded how do you charge both batteries. Does anyone have a wiring diagram for this.
 
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Bob
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PostPosted: Sun Jan 24, 2010 8:08 pm    Post subject: Re: JD 4020 24v alternator wiring Reply to specific post Reply with quote

WHY don't you get the proper 24 Volt alternator with floating ground?

The setup you have will be a NIGHTMARE to anyone who ever has to work on it and straight 24 Volts above ground is enough voltage to WELD with!
 
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buickanddeere
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PostPosted: Sun Jan 24, 2010 8:43 pm    Post subject: Re: JD 4020 24v alternator wiring Reply to specific post Reply with quote

Your buddy was guessing instead of purchasing a service manual instead of knowing.
Now he is going to have to purchase another alternator which floats. Or repair the old generator.
He didn't save any $$$ being cheap.
 
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quake
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PostPosted: Sun Jan 24, 2010 9:46 pm    Post subject: Re: JD 4020 24v alternator wiring Reply to specific post Reply with quote

That what I thought. It looks like you would have to have an isolated or insulated positive and negative.
Thanks for the info.
 
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Tom 43
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PostPosted: Mon Jan 25, 2010 4:42 am    Post subject: Re: JD 4020 24v alternator wiring Reply to specific post Reply with quote

Where does the term "floating ground" come from? The generator, starter, and regulator are all grounded to the positive terminal of the battery. They are grounded through dedicated wires and insulated from the frame. I have heard the "floating" term before and am curious as to its origin.
 
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LarrySTN
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PostPosted: Mon Jan 25, 2010 5:27 am    Post subject: Re: JD 4020 24v alternator wiring Reply to specific post Reply with quote

Tom43 On a 4020 24 volt system, the starter generator and regulator are NOT positive ground to the frame. The starter generator and regulator ALL have positive and negative connections and are isolated from the frame, thus they all have a "floating" ground. One battery has a connection from positive post to chassis while the other battery has a connection from the negative terminal to the chassis.
 
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John T
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PostPosted: Mon Jan 25, 2010 6:07 am    Post subject: Re: JD 4020 24v alternator wiring Reply to specific post Reply with quote

The term "floating ground" in this context means the Starter and Generator do not have either electrical terminal bonded to the case/frame as the case in most typical 6 or 12 volt tractor gennys and starters. The terminals exit the case/frame and are insulated from it. The genny is 24 volt and charges BOTH 12 volt batteries at once in series and the starter is 24 volts NOT electrically tied to case/frame.

PS this is for the 24 volt systems of course NOT if they were converted to 12 volts

John T
 
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buickanddeere
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PostPosted: Mon Jan 25, 2010 1:57 pm    Post subject: Re: JD 4020 24v alternator wiring Reply to specific post Reply with quote

Because the 24V starter,generator and regulator make no reference to chassis to operate.
They could be bolted to a 2X4 and operate just the same.
 
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quake
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PostPosted: Tue Jan 26, 2010 4:17 pm    Post subject: Re: JD 4020 24v alternator wiring Reply to specific post Reply with quote

I rewired the batteries and hooked it up like this.

 
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44 Diesel Tech
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PostPosted: Tue Jan 26, 2010 5:07 pm    Post subject: Re: JD 4020 24v alternator wiring Reply to specific post Reply with quote

[quote="quake"](quoted from post at 01:17:15 01/27/10) I rewired the batteries and hooked it up like this.

Interesting, What are you doing about lights and gauges? To answer your question, one batt. must be bad.
 


Last edited by 44 Diesel Tech on Tue Jan 26, 2010 5:11 pm; edited 1 time in total
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quake
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PostPosted: Tue Jan 26, 2010 6:42 pm    Post subject: Re: JD 4020 24v alternator wiring Reply to specific post Reply with quote

Believe it or not a John Deere tech told me it would be no problem to hook up the lights and guages.this tractor has bouble lights on the front. I just looked a wiring diagram for the lights. He must have been talking about another 4020 Smile This is real interesting how they use both batteries to run the 12v lights with what you call a floating ground. I can fix this problem but it's gonna hurt me brain. I have thought about insulating the alternator.
It's up to the owner to decide.
 
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hunter64
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PostPosted: Tue Feb 17, 2015 7:49 pm    Post subject: Re: JD 4020 24v alternator wiring Reply to specific post Reply with quote

quake wrote:
(quoted from post at 17:17:15 01/26/10) I rewired the batteries and hooked it up like this.

I installed the 24v alternator and wired the batteries like the diagram. I was told by the electric shop to disconnect the old regulator but now I have no lights any thoughts?
Hunter
 
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Tx Jim
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PostPosted: Wed Feb 18, 2015 4:12 am    Post subject: Re: JD 4020 24v alternator wiring Reply to specific post Reply with quote


12 volt lights bulb don't last very long on a straight 24 volt system such as your drawing. You need 24 volt light bulbs.
 
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