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Converting a 420 to 12v with an alternator??

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Tyler, MO

11-13-2002 07:47:38




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I have the alternator already mounted on my 420. I plan to convert it to 12volt. How do I go about the wiring? Do I need a resistor to lower the voltage to the dist? Should I get a electronic ignition? If anyone that see's this would have a rough idea of how to run the wiring like to the alternator and switches/guages please let me know or reply to this post. Thanks




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G Taylor

11-13-2002 16:48:41




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 Re: Converting a 420 to 12v with an alternator?? in reply to Tyler, MO, 11-13-2002 07:47:38  
It's usually simpler to just restore the origional 6v system than custom figure out wiring for the non electrician. The origional system works fine in sub zero weather with a quality battery, large cables, low resistance connections and with a engine,carb and ignition in decent tune.



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tubba_JD420C_ny

11-14-2002 16:16:56




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 Re: Re: Converting a 420 to 12v with an alternator?? in reply to G Taylor, 11-13-2002 16:48:41  
Amen on that! G Taylor is right. I just finished re-wiring my formerly non-charging 420C and I replaced the generator, regulator, battery cables, etc with new 6-volt items. The big 6-volt size battery cable makes all the difference. So many 6-volt systems get rigged with the skinny 12-volt cables and that chokes off the current so that the starter doesnt get enough juice. Power is volts times amps, so if you have fewer volts, you need more amps to get the same power and you get more amps thru a big cable than a skinny one. Good luck, just my 0.02

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Clooney

11-13-2002 12:43:44




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 Re: Converting a 420 to 12v with an alternator?? in reply to Tyler, MO, 11-13-2002 07:47:38  
Tyler, assuming a Delco 10-SI 3 wire alternator the change over is not too complicated but a little tricky on the 40-420 due to the remote regulator & load circuit at the regulator. Most alternator conversion articles just gloss over the fine points like ignition feed, wire gauge & gage polarity. ~I will E-Mail you a fully explained wire diagram showing a Delco 10-SI on a 420 & showing the resistors & wire gauges complete with regulator by-pass & excitation circuit, look for it later tonight as I don't have access to my home network from my present location

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Tyler, MO

11-14-2002 09:05:52




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 Re: Re: Converting a 420 to 12v with an alternator?? in reply to Clooney, 11-13-2002 12:43:44  
Thanks for the color schmeatic!
the only thing is is that I have a one wire delco alternator with an internal voltage regulator. What do I have to do different for this? I assume that since the diode is internal, I wont have to add one in an outside circuit? I am sorry that I wasn't too clear about exactly what I was going to do. I am switching to a 12v, alternator, negative ground system. The alternator is a one wire delco with an internal voltage regulator. I have the alternator mounted on the tractor already. I hope this helps clear this thing up. Tyler

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Clooney

11-14-2002 11:24:37




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 Re: Re: Re: Converting a 420 to 12v with an alternator?? in reply to Tyler, MO, 11-14-2002 09:05:52  
Tyler, wire it the same except you wont need the yellow wire with the resistor & diode from the ign switch to the #1 terminal & you wont need the green wire to the #2 terminal.
~If the alternator has been sitting on the shelf for a while you will probably need to pull the plastic regulator cover & jump power from the alternator BAT post to the regulator #1 terminal to get it to charge for the first time, then it should charge on it's own after that until it sits for an extended time..
~Due to the belt pulley ratio you will probably have to bring the RPM to high idle every time you start it to get it to charge, but once initiated on each start cycle it should charge ok. ~I usually don't recommend a 1 wire alternator on a 2-cylinder Deere for that reason but of all the 2-cylinder tractors the 420 is about the best. They do make a low RPM cut-in Delco but it is more money & harder to find.

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Steve - IN

11-14-2002 10:06:53




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 Re: Re: Re: Converting a 420 to 12v with an alternator?? in reply to Tyler, MO, 11-14-2002 09:05:52  
Tyler,

You can find a good discussion with schematics of the 3 vs 1 wire Delco at the link below.

You should take note of the speed the normal one wire Delco "trips" at -- an RPM level you'll never see. So you'll want to either replace the regulator in the innards of the Delco, or change the pulley size to turn it faster.

Steve

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Steve - IN

11-13-2002 09:05:43




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 Re: Converting a 420 to 12v with an alternator?? in reply to Tyler, MO, 11-13-2002 07:47:38  
Tyler,

There are a number of articles on converting a tractors electricals already published on this web site which answer your questions - plus give you some pros and cons.

Link



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Tyler, MO

11-13-2002 07:51:09




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 Re: Converting a 420 to 12v with an alternator?? in reply to Tyler, MO, 11-13-2002 07:47:38  
Also, I plan to change the ground to negative? What do I need to do to accomodate this?



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Dan

11-13-2002 20:48:08




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 Re: Re: Converting a 420 to 12v with an alternator?? in reply to Tyler, MO, 11-13-2002 07:51:09  
Just change the wires on the coil. You should use either a 12 volt coil with internal resister or put a chtrysler type ceramic resister in the line that goes from the ignition switch to the coil. I have an alternator and 12 volts on my JD 430 and would never consider going back to 6 volts.



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