John Deere 4100 won't charge battery

[brifo]

Hi guys,
I'm looking for some help 'cause I'm out of ideas. I have a 2001 John Deere 4100 and it isn't charging the battery. It all began after I finished mowing and shut it down. A few minutes later I tried starting it and it wouldn't turn over. I jump started it and although it turned slowly, it caught and started so I finished my work. The next day I went to start it and again it wouldn't turn over, just click like a low battery. I cleaned the battery terminals and jump started it again. I began mowing again and after a few minutes the lights began getting brighter and then they blew out (a voltage surge of some sort). I continued mowing and about 10 minutes later the engine stopped like I had turned it off. I replaced the battery and it now starts and runs fine, however, I am getting less than 12 volts at the battery, the same number whether it is running or not. I checked the alternater and it is putting out the 28-32 AC volts I was told it should. So I just replaced the voltage regulator ($143) and it is still less than 12 volts at the battery. Sorry for the long winded explaination but I'm hoping someone else has had a similar problem and can help.
Thanks in advance for any input anyone may have. Brian

[Upper5Percent]

During Alternator Regulated current output test...
If amp output is high but battery voltage does not increase...test the battery and verify ALL GROUND CONNECTIONS...

[brifo]

Thanks for the input Paul. The battery ground is good, I'll check to see if there are any other grounds that are bad. How do I perform the "Alternator Regulated current output test" that you refer to? The alternator is suppose to put out 20 amps max (which I can't test that high with my meter) but I don't know what the regulator is suppose to put out for amperage.

[JDFANATIC]

brifo,

Welcome to the forum!

[brifo]

Thanks for the warm welcome! A lot of good stuff in here, I'm glad to be a member.

[Upper5Percent]

Originally Posted by brifo

Thanks for the input Paul. The battery ground is good, I'll check to see if there are any other grounds that are bad. How do I perform the "Alternator Regulated current output test" that you refer to? The alternator is suppose to put out 20 amps max (which I can't test that high with my meter) but I don't know what the regulator is suppose to put out for amperage.

If you do not have the Technical Manual for your tractor, I would recommend you purchase it...

You still have to test your BATTERY...which is probably where the problem lies...

[brifo]

I ordered the Tech manual on Monday but it hasn't come in yet. The battery is brand new, replaced it first, and then the voltage regulator. I'm hoping the Tech manual has the schematics and I can find some diode or relay that might be bad. But without the manual, I sit here and impatiently wait...

[Upper5Percent]

Originally Posted by brifo

I ordered the Tech manual on Monday but it hasn't come in yet. The battery is brand new, replaced it first, and then the voltage regulator. I'm hoping the Tech manual has the schematics and I can find some diode or relay that might be bad. But without the manual, I sit here and impatiently wait...

If you still had a bad voltage regulator...after you had replaced your battery...the new battery could now be toast...

So when you get your manual...you will find an Electrical System Checkout Section and an Electrical System Diagnosis Section...you have to follow steps similar to a flowchart...after you slough through the 19 or so pages...you will understand why it is so hard to try an debug electrical problems on the internet...

[brifo]

ouch, I hope not. This is getting expensive...
Thanks for the advice, Paul. I know it is hard to trouble shoot online, wishfull thinking on my part that someone had the same problem and said, "oh, do this..." I'll be sure to put my solution on this post, whatever that may be...

[brifo]

Is the hour meter in series with the voltage regulator and battery and could it have blown when I had the power surge, causing my problem? I'm assuming I can check the hour meter for resistance like any other electrical load?

[brifo]

Well I finally received the tech manual today, too many pages in the Electrical system section and not enough time left in the day to go thru it all, so I did what most guys do, looked for the quick test/fix. After 3 hours of testing components and analyzing the schematics and not finding a bad part, I switched the "K7 Safety Relay" with the "PTO Light Relay" (because they look identical) and the charging system started working. Oddly enough, the PTO system appears to be working fine also. So my best guess to the problem is the relay was/is partially damaged from either the battery cell popping or the voltage surge and although it was still passing current thru it, it wasn't enough to turn the voltage regulator on to charge the battery. I also put the old voltage regulator back in and it works fine, $140 wasted.
If anyone needs any details to help troubleshoot your own problem, let me know, I'd me happy to share them.

[Upper5Percent]

You want to follow the STEP BY STEP Electrical System Diagnosis Section...do NOT jump a step unless they tell you to...it takes time, but that will find your problem...
And, in general will save you from buying too many unneeded parts...especially since electrical parts are NOT returnable...

[JDFANATIC]

Originally Posted by brifo

Well I finally received the tech manual today, too many pages in the Electrical system section and not enough time left in the day to go thru it all, so I did what most guys do, looked for the quick test/fix. After 3 hours of testing components and analyzing the schematics and not finding a bad part, I switched the "K7 Safety Relay" with the "PTO Light Relay" (because they look identical) and the charging system started working. Oddly enough, the PTO system appears to be working fine also. So my best guess to the problem is the relay was/is partially damaged from either the battery cell popping or the voltage surge and although it was still passing current thru it, it wasn't enough to turn the voltage regulator on to charge the battery. I also put the old voltage regulator back in and it works fine, $140 wasted.
If anyone needs any details to help troubleshoot your own problem, let me know, I'd me happy to share them.

brifo,

Expensive, but glad you figured it out. Hopefully this will help others in the future.

[brifo]

Thanks, I hope this can help someone in the future as well, 'cause if I can save someone the time (and money) that I invested, than that is what these forums are all about.

[brifo]

Update: I tested the relay that was in the charging system (per the tech manual) and it is fried. The reason it worked in the PTO system is that system is an "open" system that under normal conditions, the relay is not energized. The charging system requires the relay to be energized to close the circuit and allow charging. I also did a search for the relay because John Deere wanted $90+ for it which seemed a little pricey to me. I found a cross reference to a Subaru Starter Interupt Relay and I ordered it thru the Subaru dealer for $42, it is identical. I could have saved a few more $'s if I had ordered it online from a Subaru Parts website, but I didn't want to wait any longer. Who knew an Auto dealer would be the cheaper alternative.