JD 1070 charge light help?

[Zeke56]

Hey, that's great. Now we have one 1070 that charges right and one that doesn't. This should make it easy. All we need is to put a voltmeter across the battery and an ammeter in series with the + lead to the battery. Then we record those two readings at rest and at various RPMs, with and without lights on.
If the batteries are good, doing that test should tell us all we need to know.

Start by recording the volts and amps with the motor off and lights on at 5 minute intervals until the voltage drops below to 12.2 volts or so. Try not to go to far below 12.2 volts. That will tell us the basic state of the batteries.

I sure do like those 1050/1070 series JDs. Some of the best.
rScotty

Thanks, rScotty. I'll be giving these last several suggestions a go after the next couple days. The "work" bay in my shop has a truck that will probably be out tomorrow. I'm thinking that the battery's fine where it starts easily in below 0 temps as long as I keep the charge light flashing to a minimum? I only run the flashers minimally when plowing the mouth of the driveway. I've been a "daytime snowplower" all this season. The 1070 has been very reliable until this electrical problem Know quite a few happy 1050 owners. Dependable compact tractors, generally.

 

[Zeke56]

I'm no electrical expert but if I had a persistent electrical problem with one of these tractors I would not only check the battery to frame ground but I would also check the engine to frame continuity. Some of the components were painted before assembly and the ground was carried in the connection bolts. As an example I have two JD 950's and none of the rear lights worked because the rear fenders had lost their ground. Apparently the design was adequate when the machine was new but failed with age. I have added ground straps to solve the problem.

Never thought to check the engine to frame continuity, but I now will. FWIW, these lights are working fine until and if I let that charge light remain on by running it above 1600 rpms with lights off. Need to use even less rpms if I want to run some of the lights. I agree with a couple others here, that it very well could be the alternator. I'll do the suggested checks in a couple days and report back. I'll also verify all the grounds mentioned.
Thanks for your feedback.

 

[pmsmechanic]

You know this just crossed my mind. If the voltage regulator is separate from the alternator you should take that and have it checked too. The problem might be in the voltage regulator.

 

[Dave M7040]

Zeke

I received a WSM from Joecdeere to better understand your tractor.

It's charging system is not like a GM or normal alternator but rather a dynamo.

The difference being with a "normal" alternator, the magnetic field inside the alternator is produced by coils of wire and the regulator varies the amount of current flowing through those coils of wire to change the alternator output whereas inside a dynamo, the magnetic field is produced by real magnets and thus there is no control of what is happening inside the unit.

The dynamo is sized to match the expected electrical loads on your tractor and if and when there is too much current, the excess is turned into heat and dissipated by the regulator fins.

The Alternating Voltage output of the charging unit needs to be verified.

Do you have a multimeter and are comfortable using it. The ones adequate to help you sell for less than $10 like this one from Amazon.

Set multimeter to measure AC voltage with a scale of 200 volts. On the meter I posted, the correct position one be one more step to the right.

Disconnect electrical plug at dynamo and connect test leads. At full engine rpm's you should read 40 volts or more.

The WSM is excellent. If you will do the first test I suggest I will have figured out the next one you should do.

Dave M7040

 

[Zeke56]

You know this just crossed my mind. If the voltage regulator is separate from the alternator you should take that and have it checked too. The problem might be in the voltage regulator.

The VR is separate from the alternator. Brought the previous VR to an electrical guy and it is not "testable". The current VR is brand new and has the same symptoms (results).

 

[Zeke56]

Zeke

I received a WSM from Joecdeere to better understand your tractor.

It's charging system is not like a GM or normal alternator but rather a dynamo.

The difference being with a "normal" alternator, the magnetic field inside the alternator is produced by coils of wire and the regulator varies the amount of current flowing through those coils of wire to change the alternator output whereas inside a dynamo, the magnetic field is produced by real magnets and thus there is no control of what is happening inside the unit.

The dynamo is sized to match the expected electrical loads on your tractor and if and when there is too much current, the excess is turned into heat and dissipated by the regulator fins.

The Alternating Voltage output of the charging unit needs to be verified.

Do you have a multimeter and are comfortable using it. The ones adequate to help you sell for less than $10 like this one from Amazon.

Set multimeter to measure AC voltage with a scale of 200 volts. On the meter I posted, the correct position one be one more step to the right.

Disconnect electrical plug at dynamo and connect test leads. At full engine rpm's you should read 40 volts or more.

The WSM is excellent. If you will do the first test I suggest I will have figured out the next one you should do.

Dave M7040

Thanks a lot, Dave. I do have a multimeter, but not very competent in using it.
I have a friend and neighbor who is very competent with both tractors and multimeters. I'll run your suggestion by him and get back to you with the results. My friend has been kinda stumped with this electrical problem so far. We've ruled out a bunch of things. Just need to find the main issue.
Thanks again.

 

[Dave M7040]

Much of the advice you have received is not wrong just not applicable to a lower tech level charging system your tractor has

Motorcycle mechanics are much more used to charging systems which have to get rid of excess amperage by turning it into heat.

The fact that your charging light is coming on at high engine speeds leads me to believe your dynamo is not producing high enough alternating voltage until it is spinning fast.

If you post a picture of the face of your multi meter I can easily tell you how to set it to do this one simple test.

Dave M7040

 

[rScotty]

Thanks, rScotty. I'll be giving these last several suggestions a go after the next couple days. The "work" bay in my shop has a truck that will probably be out tomorrow. I'm thinking that the battery's fine where it starts easily in below 0 temps as long as I keep the charge light flashing to a minimum? I only run the flashers minimally when plowing the mouth of the driveway. I've been a "daytime snowplower" all this season. The 1070 has been very reliable until this electrical problem Know quite a few happy 1050 owners. Dependable compact tractors, generally.

That is right. You could run it that way from now on if you wanted to, and if you didn't need lights. The battery on a diesel really doesn't do much except start it and act a reservoir. It won't hurt the battery at all to start the tractor and then just sit there running a few lights from time to time. Nor will it hurt the alternator. There are some types of Voltage regulators that could be hurt by doing that, but frankly if yours is that type it is already a gonner.

After a few days running without charging the battery will begin to lose power and you will know it is time to put it on a charger overnight. That's about the size of the downside. I've run machines in that manner for months if not years until I got around to fixing them. BTW, the new "smart chargers" that sense when a battery is fully charged and then go into "float" mode are worth the money. Form my garage days I have a whole lineup of battery chargers, but the single simple "smart charger" is better than them all.

If you do are curious about how much reserve that your battery has left, it is easy to tell on a typical lead acid battery. Simply measure the D.C. voltage across the battery terminals when they aren't connected to anything. 12.7 volts is fully charged, 12.4 volts is 75% left, 12.2 is 50%% left, and 12.0 is about 25% power left before it goes clear flat. Try not to drain it below 12 volts and you will be fine. It's not a good idea to leave a discharged battery outside below freezing.
rScotty

 

[Dave M7040]

Surprisingly, many of these "low tech" charging systems make use of an SCR, or one of its variants, to control output voltage. It does away with the need for rectifiers and the problem of excess heat that has to be dissipated. I had an old Bolens G-14 from 1978 that used such a system. I too agreed from my beginning posts that the dynamo isn't up to par.

Here is the internals of a permanent magnet regulator I found attributed to John Deere.

The AC output has to be rectified to direct current and diodes inside the regulator are doing that but the excess voltage is bled off with a Zener diode.

Dave M7040

 

[zzvyb6]

Well, wouldn't you know it. Fired up my 1070 today after a few weeks and my charge light came on. Went off after about 2 minutes.

VRs for it are all over ebay. I will check VR connections and alternator output.