JD 4100 Compact Won't hold charge

I need some help in determining what & why my 4100 compact won't hold a charge.
I have been fighting this problem for quite awhile.
The strangest problem with it is that is a somewhat sporadic problem.
I've cleaned the battery terminals, I've replaced the entire cables.
Put a new battery in a few months ago.
After the new battery it would start perfectly....
For a week or two.
Then the tractor sat for a week or two.
Went out one morning, totally dead, the gauge lights didn't even come on.
I noticed one time when trying to get it started that it kind of clicked when turning the key, sometimes it would click, next time, nothing.
I replaced the key switch.
Slow charged the battery all day.
I had 12.50 volts at the battery.
Naturally it started right up.
I left sit for a while at an idle.
About 30 minutes went by, put my meter on the battery posts. It was showing 12.3 to 12.4 volts running...
Next morning, about 12 hrs. it fired right up.
The second morning about 36 hrs after the new switch & charged battery, it clicked a little, dash lights came on, but wouldn't even try to turn over.
I'll be taking the battery to be tested on Monday.
If the test shows the battery is good...
What is my next move?
Many thanks,
Jeff

I'm anxious to hear the results of the battery test. Otherwise, my guess is there is a terminal somewhere that is not completely clean. Could be the battery, but has to be in the electrical system somewhere.
BTW, the flasher switch and or directional signal switch is off....right?

Battery is probably ok. Sounds like a leakage problem gradually discharging the battery. My first suspect would be a problem in the alternator.

The alternator is likely bad. Bad is not much of a diagnosis, but the best way to check is with your volt meter when running
(after a good charging so the battery is full). The throttle should be about one half or so. The voltage should be 14.2 to 14.6
volts when measured from battery terminal to battery terminal. If it is, the system is charging, but might still be taking away
current when turned off. After the above voltage check, turn it off. Take the positive battery terminal off the battery and use
your volt meter between the battery post, and the terminal. (one lead to each) If the voltage reads more than one volt, (or using
a milliamp setting, about 120 to 150ma) there is a leak. I woud have the alternator checked at a Auto Electric shop. If it is
OK, there must be a leak in some other circuit. Jim

I have a PDF of the technical manual for the 4100, you're welcome to if, if wanted
shoot me your email, FYI for some reason the 4100 was prone to regulator and alternator problems back when they were new

Like Red's? Are they still in business?

It does sound like a battery drain, or alternator not putting out it's full potential.

The 2 can be related. Most auto supplies can test the alternator. It is only a 20 amp alternator according to Tractor Data, so don't let them tell you it is "only" putting out 20 amps, cause that's all it is designed to do.

If you take the battery in for a load test, be sure it is fully charged first in order to get a good test.

Have you checked the alternator belt for wear and tightness?

I went through a similar problem with my 4100. Constant dead batteries and voltage tests appeared like it was not charging. What it turned
out to be was a small timer located at the front of the tractor near the radiator. This timer controls the heating of the glow plugs. What
was happening was the timer was keeping the glow plugs on all of the time. It would then discharge the battery. What I did was unplug this
timer. To heat the glow plugs without this timer what you now do is put the tractor in gear and heat the plugs like you normally would.
Tractor must now be in gear for the glow plugs to heat. I suggest you google this for a better description of what this timer looks like and
its function. Hope this helps.

Yes and seem to do well. I am a customer upon a need for parts for my repairs. They say something like " is it from a late 40s Chevy or GMC. I say GMC, they say high deck or 221. I say high deck. They turn around and pull the parts off the shelf. Jim

" It was showing 12.3 to 12.4 volts running..."

NOT sure what all you've got going on, but battery voltage while running and charging should be 14 and a half Volts, give or take a half volt.

At 12.3 to 12.4 Volts, the charging shystem is DEFUNCT.

A quick update...
Battery tested ok.
I had to jump it again the other day. As soon as I had it going I put my meter on the battery posts. At half throttle the meter was showing about 9.5 volts.
I tested the alt. per the Tech manual. It was putting out 52 volts AC, 50 volts AC is minimum...
So,
Back to the Tech manual and see what my next step is...

Well,
Sunday morning, here is my latest update on this problem.
I had said battery tested ok. It did using my cheapo tester.
Had it tested at my battery dealer. Yes, it was shot....
Put the new battery in yesterday, made sure the posts & the cable ends were clean.
It started right up, ran it about 15 minutes.
Went back and did the alternator test per the JD tech manual.
The alt. is putting out 52vac when its unplugged.
Hooked the alt. back into the system.
I took a voltage reading at the battery before restarting, I had 12.4vdc at the battery.
Restarted & brought it to half throttle.....
12.4vdc at the battery.
So,
I have no charge into the battery.
Next step??
Replace the regulator??
I'm not an electrician....
Relying on the experts on here....
Thanks...
Jeff

(quoted from post at 08:42:27 11/11/18) Well,
Sunday morning, here is my latest update on this problem.
I had said battery tested ok. It did using my cheapo tester.
Had it tested at my battery dealer. Yes, it was shot....
Put the new battery in yesterday, made sure the posts & the cable ends were clean.
It started right up, ran it about 15 minutes.
Went back and did the alternator test per the JD tech manual.
The alt. is putting out 52vac when its unplugged.
Hooked the alt. back into the system.
I took a voltage reading at the battery before restarting, I had 12.4vdc at the battery.
Restarted & brought it to half throttle.....
12.4vdc at the battery.
So,
I have no charge into the battery.
Next step??
Replace the regulator??
I'm not an electrician....
Relying on the experts on here....
Thanks...
Jeff

Click to expand...

Running an alternator open circuit is usually not a good idea due to high voltages. . The alternator needs to be bench tested at a shop where voltage can be monitored as the alternator is tested up to full load .
The alternator may also have been damaged when the tractor was jump started from dead. The alternator reads the dead battery as a very low impedance . The alternator goes to max charge for an extended period of time , overheats and fails .
Just because an alternator maybe “rated” for example 55amps . That 55 amps is an intermittent max for 5 minutes and then the load should not be more than 2/3 to 3/4 of the max nameplate rating.
The battery was probably ok until the phantom current drain has ran it dead flat . This will damage any battery and repeat draining to dead will ruin batteries for certain .
Need to Solve the problem first as treating the symptoms will not be satisfactory.

buickanddeere,
Sent you an email.