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  1. #1
    New Member
    Join Date
    Mar 2008
    Posts
    11
    Location
    NW Illinois

    Default 790 Battery/Alternator Issue

    Got the 790 home on Friday last week. Thought it was a bit slow starting at first but hey, it hasn't been ran a whole lot lately most likely. Probably just have to use it a bit to blow the cobs out. Use it a bit Friday and Saturday, probably almost an hour on the clock. Come Sunday, click click no start! Negative battery cable was loose. I tightened it and jumped it and everything seems fine. Run it about an hour, let it idle instead of shutting off, and then shut it down in a place I know I can get to it to jump. Sure enough, no start again. Clean up every electrical contact on battery and alternator, jump it and put it away. Can't find stinking multimeter (still moving) so I throw my motorcycle battery charger on it.

    The battery took a charge and has been starting it each time I've tried over the past three days. I haven't really used it yet but I borrowed a multimeter and it seems like the battery voltage does not increase at all when the tractor is running no matter what RPM it's turning. Have done a bit of reading since originally posting, the battery discharge light is not coming on when the key is turned on, guess that may be an issue! So it's not going to tell me if it isn't charging.

    Is the alternator bad or something else in the chain? What AC voltage is the alternator supposed to put out when turning? The dealer will fix it but I kind of want to figure out what's wrong to double check them.

    Thanks in advance for any help!
    Last edited by maut9r; 04-09-2008 at 11:43 PM.

  2. #2
    Epic Contributor Soundguy's Avatar
    Join Date
    Mar 2002
    Posts
    47,271
    Location
    Central florida
    Tractor
    ym1700, NH7610S, Ford 8N, 2N, NAA, 660, 850 x2, 541, 950, 941D, 951, 2000, 3000, 4000, 4600, 5000, 740, IH 'C' 'H', CUB, John Deere 'B', allis 'G', case VAC

    Default Re: 790 Battery/Alternator Issue

    Find out why your idiot lamp ain't working.. check fuses and the lamp element.

    Looks like time for a alternator test after that.

    soundguy

  3. #3
    New Member
    Join Date
    Mar 2008
    Posts
    11
    Location
    NW Illinois

    Default Re: 790 Battery/Alternator Issue

    The dealer picked it up today and found the problem. Two wires up near the voltage regulator were un-plugged. One was a ground and one was the wire for the indicator light. Plugged them in and everything looks good. Getting about 14.5 - 15 volts at the battery now when the tractor is running.

  4. #4
    Super Member RobS's Avatar
    Join Date
    Jun 2000
    Posts
    6,235
    Location
    SW Michigan
    Tractor
    John Deere 790

    Default Re: 790 Battery/Alternator Issue

    Good to hear you got it fixed, now to enjoy it!
    Rob
    ****************
    John Deere 790, 70 FEL, 7 BH, 513 cutter and other fun stuff

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