JD 730 D 4 - 6 volts convert to 2 - 12 volt 97

JD 730 D 4 - 6 volts convert to 2 - 12 volt

He has 4- 6 volt batteries now..

Clooney

Clooney

Quote: "You guys have any ideas on the 12 volt part of the harness that is backfeeding and or discharging?"

--I covered that in the first post but you must have missed it in all the words explaining the system operation.. It should be easy to find the problem [if you even have one]..

First, MAKE SURE the ign switch is turned off & all lights & accessories are off [including the cigarette lighter].. Then remove that center small battery wire between the center battery posts & chassis ground,, then hook a 12 volt test light between that wire & the tractor frame.. IF, the test light lights [or glows] you have a short between the 24 volt system & ground [or something is hooked to the 12 volt system that doesn’t belong].. If the test light doesn’t light [or even glow softly] you probably don’t have a problem..

IF, the test light lights [or glows] - start by removing one then the other battery wires from the starter’s connection studs, if the light goes out you have a shorted starter [remove the starter & pull it apart & look for brush material or dirt piled up in the bottom of the starter].. If the light still doesn’t go out then start removing the battery wires from the voltage regulator & generator until the light goes out.. When you find the wire that when removed turns the light out post back & I’ll talk you through the repair or help you isolate what’s shorted.

Note: the starter is usually the cause of the battery run-down but it also could be something else..

Quote: “ bought two 975 CA Interstate Heavy duties to do the job.. Is this enough battery to start the beast?”

--Yes, it will start it ok but you really won’t know at how cold it will start it until winter comes.. Those 2-12 volters have to be real strong to start that diesel at sub 0°…

JDClooney@aol.com

Quote: "First question, will the two 12v"s do the job?"

--Yes, but you will need the largest CCA 12 volt batteries you can fit in that battery box.. The more Cold Cranking Amps the better as those 2-cyl diesels crank over with difficulty when extremely cold.. [BIG batteries with lots of CCA will work fine]..

Quote: "Also I have one small lead for the 12 volt system (guages ect.) When I hook it up I have been told from the previous owner it draws the system down"

--That small battery ground wire is for the two 12 volt systems to operate correctly.. When the batteries run down with that wire connected it usually means you have a short to chassis ground between the 24 volt part & the 12 volt part [usually the starter].. See below for details on operation.. You might try hooking that wire up & seeing if the batteries run down, if so try removing the two big battery wires from the starter & seeing if the system stays up, if so remove the starter & clean the brush debris from the bottom & make sure NO internal wires are shorted to the starter case.. As a quick test- with ALL the lights & accessories turned off you shouldn’t get a spark when that center battery wire is hooked to ground.. Or a 12 volt test light shouldn’t light when hooked between that removed center wire & the tractor chassis. If you get a spark, or a test light lights you have an accessory left on or a short to ground in the 24 volt part of the system [usually the starter is a common place]..

Quote: "Also, other weird thing, when I switch the lights on the gauges work?"

--That"s usually an indication that the center battery ground connector wire isn"t connected from the center battery posts to the tractor chassis so the lights on one side act as a chassis ground for the gages & other side.

Quote: " I have no experience with this electrical system"

--Joe, the 24 volt 2-cylinder diesel system is rather complex when FIRST looked at [or worked on] but once you understand it"s reason & function it isn"t too bad [see the below operating principle]..

**2-Cylinder 12/12/24 volt operating principle**

--Basically your tractor has 3 electrical systems on it....
A 12 volt positive ground system using 1/2 the batteries at positive ground,,, A 12 volt negative ground system using 1/2 the batteries at negative ground,,, & a 24 volt system using all the batteries is series…

---The tractor has an isolated ground 24 volt system.. That means that both the starter & generator are “completely isolated” from the tractor frame [& chassis] so no part of the 24 volt system uses the tractor frame [or chassis] for either a power or a ground circuit.. Each of the 12 volt systems DO use the tractor frame [or chassis] to carry power for either power [one 12v side], or ground [other 12v side] circuit.

--The key to that system is a simple little wire running from the 2 [center most] posts between the center batteries to the tractor frame. Without that wire the system wouldn’t have either 12 volt system.

---What you have with the Deere 24 volt system: Is one 12 volt ‘negative’ ground system that runs from the positive most battery post in the battery chain to that little wire between the batteries, about ½ the lights & accessories are on that system,,,,, You have one 12 volt ‘positive’ ground system that runs from the negative most battery post in the battery chain to that little wire between the batteries, that runs the other ½ of the lights & hopefully the other half of the accessories,,,,, You then have a 24 volt system, that runs from the positive most battery post in the battery chain to the negative most battery post in the battery chain [all batteries in series for 24 volts]. Both the generator & starter are electrically isolated from the tractor frame & chassis so the starter is powered from the most positive battery post in the battery chain to the most negative battery post in the battery chain. The generator then charges ALL the batteries together as a 24 volt system from the most positive battery post to the most negative battery post. ___Simple as that!

--That 12/12/24 volt system is simple & functions extremely well IF all the light & accessories loads are kept even & matched on both 12 volt systems. The problems arise when more accessories are added to one side than the other of the 12 volt systems. If electrical loads AREN"T kept pretty well matched then one side of the system doesn’t charge completely & that can spell trouble for starting, as the 24 volt part that uses ALL the batteries in series can’t use the dead battery in the chain & then won’t receive it’s full 24 volts.

~Simple when you think about it.. Difficult when you just think of it…

Questions… Just post back..

JDClooney@aol.com