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  1. #1
    New Member
    Join Date
    Apr 2002
    Posts
    19
    Location
    NC
    Tractor
    L2550

    Default Battry discharge

    I have a new battery, the regulator is only 1 yr old and checks out with the shop manual testing, the alternator puts out 12 volts (the shop manual says it should be 14) after charging the battery it starts fine running for 2.5 hrs and retuirning to barn, shut off and on restart the startere clicks like a dead battery, battery reads 12 volts anyone have any ideas, thanks.

  2. #2
    New Member
    Join Date
    Sep 2005
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    0

    Default Re: Battry discharge

    A fully charged battery will show over 12.6 volts, this is with the engine off and no load. The charging system is not putting out properly if you're only reading 12 volts with engine running. Check fan belt tension, battery wire to alternator possibly even fuses, not sure on the orange things. Anyway, if all that fails, pull the alt and have it checked at an auto parts store or alt repair shop. If I've missed something, you'll know soon enough... [img]/forums/images/graemlins/grin.gif[/img]

  3. #3
    Epic Contributor Bird's Avatar
    Join Date
    Mar 2000
    Posts
    36,983
    Location
    Texas

    Default Re: Battry discharge

    glennd has it right. A fully charged battery should have 12.6 volts; not just 12 volts, and the alternator needs to put out 14 (actually I think it should be 14.2 to 14.4) volts to charge the battery.

  4. #4
    Elite Member
    Join Date
    Mar 2002
    Posts
    3,310

    Default Re: Battry discharge

    Can't add much to what Glenn said, other than the 12v you are reading is probably coming from the battery and not the alt. unless you are checking directly from the (unhooked) alternator. You can unhook the alt. from the reg. and run briefly. A good alt. should put out 20-30vac.

  5. #5
    New Member
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    Sep 2005
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    Default Re: Battry discharge

    Alternator put out 20-30 VAC ?? Alternators put out DC, they have diodes in them to recify the AC to DC. Also all alternators I have seen will put out nothing with the regulator disconnected. They require a field current to activate/regulate their output.


  6. #6
    Elite Member
    Join Date
    Mar 2002
    Posts
    3,310

    Default Re: Battry discharge

    I guess it depends on what he really has. Sometimes the diodes are in the regulator. (At least in some Yanmars).

  7. #7
    New Member
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    Sep 2005
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    0

    Default Re: Battry discharge

    Oh ok, Thanks for the info Norm, Not a Yanmar man myself, not sure the origional poster is either. MOST alternators put out DC and if they have an external regulator, will not put out when it is disconnected. However most Briggs and Kohler type engines have an alternator under the flywheel and will act as you describe, putting out a higher voltage AC with the regulator disconnected.

  8. #8
    Veteran Member
    Join Date
    Jan 2002
    Posts
    1,927
    Location
    Home-1+ acres New Hope, TX / 24 acres-Fannin County
    Tractor
    JD 950

    Default Re: Battry discharge

    Larry - Did you clean and tighten your cable connections? Not just the battery end, but also the engine and starter end? Those symptoms can also indicate a bad/loose/dirty connection. Use a wire brush and make sure all surfaces are clean. Sometimes there is a white crusty looking buildup inside the clamp that is hard to see just by a quick look. The special battery brushes work great for that.

  9. #9
    Gold Member
    Join Date
    Oct 2002
    Posts
    317
    Location
    Middle Tennessee
    Tractor
    John Deere 4410

    Default Re: Battry discharge

    Larry, is this an Honorable Discharge or Dishonorable? [img]/forums/images/graemlins/wink.gif[/img] Seriously, I agree with Bird on the alternator output. Have you checked to see if you have a slow discharge drawing amperage away from the battery while it is setting. Try touching one of the battery cables to the battery terminal with everything turned off. If you see a small spark; something is drawing juice. Make sure all of you connections are CLEAN and tight at both ends of each battery cable. Check each battery cell with a hydrometer to eliminate the possbility of a bad or shorted cell. A shorted cell can do what you are describing. Good luck.

  10. #10
    New Member
    Join Date
    Apr 2002
    Posts
    19
    Location
    NC
    Tractor
    L2550

    Default Re: Battry discharge

    I charged the battery, it read 12.9 volts last night unhooked. Took the alternator to a repairman yesterday it apparently has a bad rectifer, should be ready sometime today, the repair is 1/2 the price of a new alternator so i went with that with some misgivings I usually like to put on New when something's amiss on the tractor. I'll let you know how it works out, thanks for the help, hope I don't need more at least on this particular repair.

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