'64 JD 3020 24V Diesel battery drain

[Hayward]

Hello, I'm chasing a battery drain problem on my 3020 24V diesel. I've rebuilt the generator and it starts and charges. The problem is battery drain while parked. After studying the wiring diagram, I feel good about everything being in place. I'm confused about the reading I'm getting through the right battery cable (which is Pos (+) to the starter). I see 12.7V from + post to cable going to starter. ? It being 24V, would I read the (-) Neg voltage coming from the left battery to the solenoid ? I placed meter lead on starter post, battery cable disconnected, the other lead on solenoid with battery connected, and I read battery voltage. Does this mean my starter is grounded ??

 

[wore out]

The voltage on the stud on the engine side of the starter ''belly'' should read (+) 12 Volts (nominal) with respect to the chassis and the upper terminal on the solenoid (where the cable from the (-) post on the left battery connects should read (-) 12Volts (nominal) and the reading BETWEEN the two aforementioned posts should be (+) 24 Volts at the terminal in the side of the starter ''belly''.

Do you have the early design with ''ground'' battery cables from each battery connected to the chassis, or the updated design with a crossover cable between the batteries and a lead with a fuse or a fusible link from the crossover cable to the chassis and two circuit breakers at the starter?

 

[Hayward]

Thanks, Wore Out, for your reply. My 3020 is '64 model with neg and pos ground to trans. plate. No cross-over cable.

 

[JD Dave]

You have a parastic draw there somewhere. Set your multimeter on amps and test each isolated component across the disconnected wires one by one. If you see an amperage reading, you know which
component is at fault. Starters are a known problem if there is any metal dust inside. Maybe simple disassembly and cleaning will solve the problem.

 

[Hayward]

I have tested for mA draw on Neg cable and see none. That's what had me looking for voltage on the Pos cable. I'll start looking again tomorrow, Thanks .

 

[used red MN]

JD Dave, enlighten me is this draw inside a starter caused by metal dust something specific to a JD with the 24 volt system due to the cable connection from the battery direct to the side of the starter? I could possibly see this as happening. In most Delco starters the circuit is broken in the positive engagement solenoid when the solenoid is not being energized by the key switch during starting. The high amp starting circuit is then open so it cannot have a draw. I have never heard of any draw found in one of those circuits on these types of Delco solenoids.
To Hayward, you will need to disconnect a cable from each battery and test for the ..parasitic draw.. with your meter in a series through the disconnected cables, each battery will need its own test. In other words one lead on the post and one on the disconnected cable post clamp. The 12 volt loads are balanced on those tractors taking approximately half the load off of each battery, this includes the lights with the switch having separate circuits for each battery.
If you find a draw I would suggest first pulling the voltage regulator cover off and look at the contacts for the three sets of magnetic coils. Lightly pull on them with your finger nail to see if one pops off its contact and then stays off. If you find this, that is where your draw is from. You may be able to clean the contact with some fine grit emory cloth and get it to work. Most likely it will require replacement. I know in many other cases for these old generator systems it is hard to find a quality replacement that lasts. If I am looking it up correctly a JD regulator is $115, probably well worth the money if it lasts 5 years or more.
I am attaching an old YT post that includes a wiring diagram. The in the original diagram the circuits are identified by left or right battery by a dashed line either above or below the circuit. The copy in the post is not good enough for consistent ID of the circuits in this way.
YT post with early 3020 24V wiring diagram

 

[Hayward]

Thank you for that info, used red MN, that makes more sense. I was testing for draw from the one battery that was being drawn down with the other battery still connected in series. I will test again tomorrow and post results.
I want to add: I've rebuilt the generator (armature, field coils, brushes, & wiring) and replaced the voltage regulator. Added 2 new batteries. I also have that wiring diagram, thanks anyway.

This post was edited by Hayward on 12/16/2023 at 08:23 pm.

 

[JD Dave]

Used red MN. I heard about the metal dust somewhere but I never had the problem. Logically, it's best to consider the starter, as a unit including wiring and solenoid etc., a possible source of parasitic draw. Do the amperage test between disconnected wires and connections.

 

[Tx Jim]

I've witnessed the starter dust brush electrical drain way back in '65-'87 when I was employed at JD dealership. Field coils & brush holders are insulated from tractor frame along with remainder of 24 volt starting/generating components. Brush dust connecting the brush holders to starter frame creates the electrical drain.

 

[Resting Relics 1]

Hayward,
I'd bet money it's in the starter. Those early 24 volt setups were famous for this issue. Many even shorted out and started an electrical fire. Good Luck! John

 

[buckeye al]

Many have said to check the starter and maybe this will help with understanding WHY to do that.

The right battery + cable goes to the side post of the starter. That keeps the guts of the starter energized at all times! The
leakage current others have mentioned is from dusty, dirt coated brush holders, armature windings and field coils. Add in a bit
of moisture and the right battery's current now has a path to the frame through the starter's guts and to the housing closing
the loop. Notice how these starters do not have just a dust band but they're pretty well sealed when fully assembled. That's
to help keep 'em dry inside.

If you check the voltage from the starter's post that is connected to the bottom post of the solenoid and the frame of the
tractor, you'll see the right battery's + voltage (assuming it is not dead). You'll see - 12 from the top post to the frame, +
12 from the bottom post of the solenoid to the frame and 24 from the top to the bottom post of the solenoid. The only gap in
the 24 volt starter current loop is between the two posts inside the starter solenoid.

If as others said you set about looking for current flowing out of the right battery.... Try disconnecting the right battery's
forward cable then remove all wires from the starter's side post EXCEPT THE BATTERY CABLE. Go back to the right battery and
look for current flowing from the battery post to just the cable. This should be a zero. If not, the starter needs at least a
D & C meaning a dustin & cleanin.

Our 4020 had the very trouble you describe, chronically low right battery unless you started it every day or two. Found a 250
ohm fault in one of the field windings to the winding pole piece. Cleared that & it now sits for months & starts right up.

Not saying others have given bad advice but am only trying to maybe better explain how & why the starter (which cranks and
starts the engine very well) can be the dead or low battery problem!

Hope that helps!

 

[wore out]

GOOD advice, al!

To add to what you wrote, the innards of the generator remain connected to the (+) side of the RH battery, as well.

Dust and moisture in the generator can bleed away battery power, as well. Dirt and moisture on the underside of the voltage regulator, and the key switch can drain away power, also.

 

[wore out]

(quoted from post at 20:24:49 12/16/23) JD Dave, enlighten me is this draw inside a starter caused by metal dust something specific to a JD with the 24 volt system due to the cable connection from the battery direct to the side of the starter? I could possibly see this as happening. In most Delco starters the circuit is broken in the positive engagement solenoid when the solenoid is not being energized by the key switch during starting. The high amp starting circuit is then open so it cannot have a draw. I have never heard of any draw found in one of those circuits on these types of Delco solenoids.
To Hayward, you will need to disconnect a cable from each battery and test for the ..parasitic draw.. with your meter in a series through the disconnected cables, each battery will need its own test. In other words one lead on the post and one on the disconnected cable post clamp. The 12 volt loads are balanced on those tractors taking approximately half the load off of each battery, this includes the lights with the switch having separate circuits for each battery.
If you find a draw I would suggest first pulling the voltage regulator cover off and look at the contacts for the three sets of magnetic coils. Lightly pull on them with your finger nail to see if one pops off its contact and then stays off. If you find this, that is where your draw is from. You may be able to clean the contact with some fine grit emory cloth and get it to work. Most likely it will require replacement. I know in many other cases for these old generator systems it is hard to find a quality replacement that lasts. If I am looking it up correctly a JD regulator is $115, probably well worth the money if it lasts 5 years or more.
I am attaching an old YT post that includes a wiring diagram. The in the original diagram the circuits are identified by left or right battery by a dashed line either above or below the circuit. The copy in the post is not good enough for consistent ID of the circuits in this way.
YT post with early 3020 24V wiring diagram

Unless there's a substantial spark when connecting the battery cable, and the generator quickly heats up, stuck cutout contacts in the V.P. AREN'T the issue, and I would caution the O.P. to disconnect the batteries BEFORE deciding to take the cover off of the V.R..

One little slip while removing the cover can make a pretty good arc and let the smoke out of the system quite quickly. (You can WELD with 24 Volts!)

And DO NOT muck around pushing on the contacts while the batteries are connected.

(Don't ask how I know this!)

 

[Tech 7]

I had an issue similar to this on a 4020 a number of years back. John T who contributes here regularly, steered me to checking and cleaning
the dust around the brushes/commutator in the starter. Worked great.

 

[WTW]

Used Red, I am not JD Dave, rather I am WTW Dave, The Starter draw that JD Dave is referring to is not a 24 volt draw. It is a 12 volt draw on one battery (Normally the right hand battery is connected correctly), This battery is connected to the starter field winding which is open on the solenoid end and normally isolated from frame ground. But, when copper brush dust / grinding shorts the filed winding to the starter case / frame it will short right battery to frame and draws the right battery down. Right and left batteries are grounded to frame at the cross over cable ground wire. A shorted field winding in generator can do the same thing but is not very common like it is at starter due to the starter produces more grinding / dust. This is where my favorite saying comes from. Just got to be smarter than a dead battery Just a kidding joke, don't take it the wrong way. Hope this helps you. DW

 

[Hayward]

Sorry for the delay in getting back to you. I had a family member pass this week and am just getting back to 'somewhat' normal.
My fuses were blown in my Fluke meter and was one reason I wasn't seeing the Amp draw on the batteries. I used my test light since it was arcing where I disconnected. The test light would light when I put it in series with the battery. I have determined it is between the solenoid and the VR. Somewhere in the wiring harness. I put a tracer tone on the wire leaving the solenoid and it's coming up on different places on the ignition switch. Even the casing around switch. Could this mean wire is grounded leaving the solenoid ?

 

[Hayward]

(quoted from post at 10:13:27 12/23/23) Sorry for the delay in getting back to you. I had a family member pass this week and am just getting back to 'somewhat' normal.
My fuses were blown in my Fluke meter and was one reason I wasn't seeing the Amp draw on the batteries. I used my test light since it was arcing where I disconnected. The test light would light when I put it in series with the battery. I have determined it is between the solenoid and the VR. Somewhere in the wiring harness. I put a tracer tone on the wire leaving the solenoid and it's coming up on different places on the ignition switch. Even the casing around switch. Could this mean wire is grounded leaving the solenoid ?

I started back on the wiring today and found the test light goes out when hot wire from solenoid to Gnd post on VR is disconnected. It also lights up with same wire connected to A2 post on generator. This is very confusing since the wiring diagram shows it is wired correctly.This is new VR and rebuilt Gen. ??

 

[wore out]

I started back on the wiring today and found the test light goes out when hot wire from solenoid to Gnd post on VR is disconnected. It also lights up with same wire connected to A2 post on generator. This is very confusing since the wiring diagram shows it is wired correctly.This is new VR and rebuilt Gen. ??

Where did the VR and ''rebuilt'' generator come from?

Are you SURE they are correct and made for this 24 Volt ''isolated ground'' system?

You must be mucking around with the BROWN wire, which is NOT GROUND, but is actually (+) 12 Volts.?

There should NOT be a terminal on the VR marked ''GND'', but there MAY be because they used the same metal VR chassis as used on 12 Volt or other NON isolated ground units and the (incorrect) GND stamping came along with the deal.

With ALL leads disconnected from the VR check (with an Ohmmeter) for any continuity between the VR ''chassis'' and each and every terminal on the VR, there should be NONE/infinity.

 

[Hayward]

I bought the VR online as a 24V regulator. Looks exactly like the old one I replaced. I had the field coils pressed in by a local alternator shop and replaced armature and brushes myself. I will admit to not being a specialist at rebuilding these units. I tried to be careful about isolating terminals on the housing.
I will test the VR chassis tomorrow.

 

[Hayward]

I have tested VR for continuity to housing and it definitely is cont. on 3 out of 4 terminals. I tested the generator terminals for continuity to housing and they also test positive. I just thought I was doing a good job ?? I assume I need to replace the VR with another type even though it's the same as the previous VR ? Then RE-rebuild the generator.