Charging problem on my John Deere 4100

   / Charging problem on my John Deere 4100 #1  

Towmater

Member
Joined
Aug 5, 2011
Messages
32
Tractor
John Deere 4100
Hello! I've had a little problem with having a dead battery. I hooked up a flamming river disconnect switch to see if that would fix it and it seems like it could be the alternator. After charging the battery on a slow charge overnight the charge was at 12.68 volts. I parked it outside during the day and let it run for 15 min with the lights on and the volts dropped to 12.02 while running. I turned the lights off, let it run some more and was slowly climbing to 12.28v and then 12.30 volts. I checked it late last night and the volts after sitting was 12.5v. Note, this is a new battery too but I thought the problem was the battery at first. Does this sound like a bad alternator to anyone? Shouldn't the volts when running be more like 13.0 volts??? Need help... I'm a rookie at this stuff but I think I am on the right track.
 
   / Charging problem on my John Deere 4100 #2  
Yes, I do think you are on the right track. Charging at half throttle should give you close to 14V with lights out.
 
   / Charging problem on my John Deere 4100 #3  
Check for proper belt tension. As stated 14v running, not at idle. Battery will (should) maintain 12.5 +- after setting. If stored in barn( any place) mice love the insulation on wires. Have found shorts.
 
   / Charging problem on my John Deere 4100
  • Thread Starter
#4  
Thanks for the advice! I think the next step is to put it at half throttle when running and double check it. I do not believe I was at half throttle when I checked it. Thank you.
 
   / Charging problem on my John Deere 4100
  • Thread Starter
#5  
Ok guys, I changed the voltage regulator per advised by dealer and no good. I changed the alternator and went from running volts with lights on from 11.97 volts to 12.23 running volts with the new alternator. Without the lights on it runs at 12.5 volts. What do you think? I'm thinking I should be ok. Hopefully so because the snow is coming. When the tractor is shut off it stays at 12.68volts which is the same as my suv. I think I have it fixed. No where near 13.90 volts though like some stated.
 
   / Charging problem on my John Deere 4100 #6  
OK, I have the same problem as Towmater. I keep a trickle charge on to keep the battery voltage up. I have had the battery load checked and it is fine. I have checked the termanals and they are clean of corrosion. With a fully charged battery of 12.9V I started the tractor. At idle 1000 rpm I have 11.95v. At 2500 rpm I have 12.21v. After 5 minutes of run time, shutting down the engine and the battery voltage is 12.7v. Are there any adjustments to tweak the voltage regulator or alternator. On my cars and trucks I just check ther battery voltage with the engine running to check out the alternator. I would have thought that Towmaster would have had 14v with a new alternator. Are there any checks that I am missing? Is there a good place to get an alternator? I can live with the trickle charger that is directly wired to the battery and easy to connect/disconnect but the wife doesn't like getting stranded in the field when she shuts down the tractor after a long idle.
 
   / Charging problem on my John Deere 4100
  • Thread Starter
#7  
Well absaroke, I'm still having the issue. Bottom line is mine is not charging enough while running. I can have a full charge and it still will drain with the new alternator. After a heavy day of use and running and starting it sometimes will die at the end of the day. I've recharged the battery and the at times will sit for three weeks with the battery disconnect switch disconnected and will fire right up. So I've feel it just is not charging enough while running per my other threads to this. I've decided I'm going to let a dealer look at it in about a week so I'll let you know, I'm tired of screwing with it. I just feel the volts should be much higher when running. Who knows, maybe the dealer sold me the wrong alternator because they were back and forth on two different ones.
 
   / Charging problem on my John Deere 4100 #8  
Well absaroke, I'm still having the issue. Bottom line is mine is not charging enough while running. I can have a full charge and it still will drain with the new alternator. After a heavy day of use and running and starting it sometimes will die at the end of the day. I've recharged the battery and the at times will sit for three weeks with the battery disconnect switch disconnected and will fire right up. So I've feel it just is not charging enough while running per my other threads to this. I've decided I'm going to let a dealer look at it in about a week so I'll let you know, I'm tired of screwing with it. I just feel the volts should be much higher when running. Who knows, maybe the dealer sold me the wrong alternator because they were back and forth on two different ones.


Most modern alternators have a built in regulator, So if the belt is tensioned correctly and all connections are good, then the alternator/regulator is not working correctly, and yes the charging voltage should be about 13.6 to 14.1
Your battery is running the tractor the alternator is pretty much not even there. Take it and have it tested or get a new one. If you by chance have and external regulator, then start looking there.

James K0UA
 
   / Charging problem on my John Deere 4100 #9  
Towmater and James

James - I agree what the voltage should be and that mine is not putting out the correct voltage.

Towmater - I'm anxious to hear the results from the dealer. I was quoted about $350 for an alternator. I will just keep the trickle charger hooked up if that is the real price.
 
   / Charging problem on my John Deere 4100
  • Thread Starter
#10  
Update. I dropped off my JD 4100 at the dealer today, printed off my thread from here and gave it to them. He confirmed when running the voltage should be right around 13.5volts. I told him I feel there is a draw somewhere considering when running it is draining and also when shut off it will drain the batteries after about three weeks. BUT- then again that might of been after running it for 1/2 a day and then parking it. I feel it is something charging related. Could very well be the new alternator is bad too. We will see!
 
 
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