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  1. #1
    Silver Member
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    Aug 2005
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    Eastern KS
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    JD 4100 HST CUT Yanmar 3TNE74

    Default troubleshooting charging system

    Battery is dying. How can I determine what is the failing component - alternator, inverter, battery? The alternator is putting off some AC voltage - specs say 30-50v, so I'll check, but even if it's putting off voltage, could it be weak on amperage?

  2. #2
    Elite Member
    Join Date
    Jul 2003
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    3,373
    Location
    Goffs Corner, KY
    Tractor
    IH 2444

    Default Re: troubleshooting charging system

    Alternator should not put out AC voltace above ripple voltage of less than a couple of volts.

    Unless the alternator is on a smaller tractor which has a seperate regulator/rectifier assembly.

    In either case the DC battery voltage should be over 14.25 volts with the engine running.


  3. #3
    Silver Member
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    Aug 2005
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    184
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    Eastern KS
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    JD 4100 HST CUT Yanmar 3TNE74

    Default Re: troubleshooting charging system

    Think I have the alternator + inverter setup. But the battery is dead now, so I can easily measure voltage across the battery while running. Any ideas how to PD if the failing component is alternator or inverter?

    Seems like the alternator should output 30-50 volts at some levels of amps. I can measure the open circuit volts, and maybe can get the inline current also.

  4. #4
    Gold Member
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    Oct 2005
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    344
    Location
    Goose Creek, S.C.
    Tractor
    Mitsubishi 1801

    Default Re: troubleshooting charging system

    Like slowrev suggested, look for about 14 volts at the battery when the engine is running. To answer your specific question though, yes, voltage can be present where amperage is not. It takes both to charge a battery. If you do have the proper voltage at the battery when the engine is running though, I wouldn't bet on low amperage. It is possible for part of the rectifier system to go bad and amperage to drop, but in a tractor where the run time compared to cranking is so long I doubt that it would be abvious. Back to what the problem can be though. Let's say you do have the voltage and amperage going to the battery, but still a cranking problem. It's starting to look like a battery problem. Before confiriming that, make sure you have good, clean connections, and check the condition of the wiring to the battery. I've seen wires that looked good on the outside, but were corroded on the inside to the point they wouldn't conduct. I'd find those with the voltage meter. No load, voltage was good, but under a load the voltage would drop considerably. The voltage meter will not read the amperage, but under the bad wire scenario what was happening was that the wire was not allowing sufficient amperage to flow. All of this, or any of it could be happening in your cranking problem.

    I recently had a charging problem on my tractor. It was as simple as a loose connection on the output line of the alternator. I hope yours is as simple. Do some checking and get some more info. I'm sure someone can get you on the right track.

    Tom

  5. #5
    Silver Member
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    Oct 2005
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    196
    Tractor
    Kubota BX1500

    Default Re: troubleshooting charging system

    Alternators do put out ac voltage. Alternators=alternating current.
    Your voltage range sounds about right.
    Suspect either wiring/connections to or from the voltage regulator, or the regulator itself. Voltage to the battery at max rpm should be about 14+ volts, DC.
    If AC voltage is measured at one side of the regulator, and less than 14+ DC volts on the other, Regulator is toast.
    If you get 14+ DC volts on the battery side of the reg, but only 12 volts at the battery, look for wires or connections between the reg and battery.
    If you have 14+ volts to the battery when engine is at full rpm, but battery won't start the engine the next day, get a new battery

  6. #6
    Super Member RickB's Avatar
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    Sep 2000
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    7,490
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    Eastern NY
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    Case 885, Ford 4000

    Default Re: troubleshooting charging system

    </font><font color="blue" class="small">( If you have 14+ volts to the battery when engine is at full rpm, but battery won't start the engine the next day, get a new )</font>

    Clean the battery connections well before condemning the battery. Can't count the no-start calls I have gone out on just to do this.

  7. #7
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    Default Re: troubleshooting charging system

    You should clean the battery terminals before you even start troubleshooting the charging stystem. A poor connection, while doing the voltage check, will give false readings.

    Many times, even clean looking connections, can lead to problems. If the post or lug is gray, sand or scrape it to bright metal. The gray color that lead turns to, is an oxide and doesn't conduct electricy well.

    You should not do the voltage check until the battery is at least charged enough to start the tractor. The batteryvoltage, at rest, should be 11.8 to 12.2 volts. Battery voltage should increase to more than 14 volts, with the engine at speed.

  8. #8
    Veteran Member
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    Jul 2005
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    1,470
    Location
    Georgia
    Tractor
    YM2000

    Default Re: troubleshooting charging system

    I havent seen that anyone has suggested a drain on the battery, though your post doesnt directly point to it either.

    Does the tractor do fine as long as its running, then become hard to start after sitting for a while? You could have a drain on the system, maybe a light on on your gauges or something powered up while the key is off.

    You could try disconnecting the negative post of your battery, connect a test light in series and see if it is lit. If it is lit, you should breifly touch the terminal to the post with the light still in place to kill any KAM(doubt you have it but, maybe). If it is still lit, leave it connected and begin disconnecting things like lights, and other loads, including the alternator and regulator. When the light goes out, you found your drain.

    I may be off base, but your post didnt really get too descriptive and I'm not really sure what we're working on either.

  9. #9
    Silver Member
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    Aug 2005
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    Eastern KS
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    JD 4100 HST CUT Yanmar 3TNE74

    Default Re: troubleshooting charging system

    Thanks everyone.. I should be more specific.

    I had a dead battery 6 weeks ago. Took it to Autozone, they tested it, said it was bad. I got an Optima. I put it in, it cranked for several times, then one day after running for an hour or so it would not crank. I charged it on the charger. It cranked for several weeks. Then a few days ago, it was dead. I jumped it, drove it 2 miles, and it was still dead. Therefore, my guess is it's alternator or inverter. I'll jump it now - dead battery - and see what voltage I have across the terminals. It should be 14 + as I understand. I suppose with it dead now, it will read 11 or such. So it 'has to be' &gt; than that, else charging system is not working. Then I need to isolate to alternator or inverter. As I recall, last time, the alternator was putting out 40+ AC volts. But I suppose the voltage could be there, but no amps -or- the inverter is bad.

  10. #10
    Epic Contributor Soundguy's Avatar
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    Default Re: troubleshooting charging system

    This doesn't address your problem.. but.. um.. Does your tractor really have an invertor? That is.. is your tractor is converting a dc supply to an ac supply voltage?
    ( A UPS power supply is essentially a battery, battery charger, and an inverter. charger maintains a 12v battery for example.. invertor converts the 12vdc to 120vac, for example.)

    Are you by chance thinking about a rectifier.. which converts ac current into dc current... etc..

    I keep seeing invertor mentioned.. and had to ask..

    ( though i have seen some garden tractors with built in invertors to run small load 120v tools away from the barn..
    etc... this is not what you are refering to is it? )

    Soundguy

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