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Thread: 7427 max input voltage/operating voltage

  1. #1
    Carb and Points! Sportbike23's Avatar
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    7427 max input voltage/operating voltage

    Hello,

    On a 16197427, does anyone know the max continuous input/operating voltage?

    If I remember correctly anything over 17 volts throws a code but I can't seem to find any info on what the ECM is safe to operate at.

    I've got an '89 C2500 5.7L TH400 that I changed to a '7427 about a year ago.

    The battery is a lithium titanate with a max charging voltage of 16.8V.

    And I have two amps that will go into protect mode at 16v so I need to keep it under that.

    Any info is much appreciated.

    Thank you

  2. #2
    Super Moderator dave w's Avatar
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    I wonder if the input voltages (battery and ignition) to the 16197427 should be externally regulated? https://www.wish.com/product/5f07d64..._wcB&share=web

    Possibly an external voltage regulator is needed for other EFI components that use battery or ignition voltage?

    dave w

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    Super Moderator dave w's Avatar
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  4. #4
    Electronic Ignition!
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    You say the lithium battery max charge is 16.8v but is the charge voltage that high? I don't know of any alternator charge system designed for over 14.8v. Anything over 15.0v is working in the realm of over charging in wet cell batteries. Usually over 15.0v we are looking at a bad battery and suspecting voltage regulator.

  5. #5
    Super Moderator Six_Shooter's Avatar
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    Quote Originally Posted by Kilroy View Post
    You say the lithium battery max charge is 16.8v but is the charge voltage that high? I don't know of any alternator charge system designed for over 14.8v. Anything over 15.0v is working in the realm of over charging in wet cell batteries. Usually over 15.0v we are looking at a bad battery and suspecting voltage regulator.
    There are higher voltage systems and alternators to suit. Some drag racers use 16V systems, that will typically charge nearer 18V. Some run no charging system at all.

    As far as the original question goes, While I haven't tested it, I would say that 16V continuous would be as high as I would push it. I did have one car that I had trouble with regulators for about 3 weeks with for some reason and one drive home, which was about 2.5 hours that night, due to traffic, the regulator failed and the charging system would go as high as 19V, with little load, so I turned on everything I could, and kept RPMs as low as I could, I tried to maintain under 16V if I could and the ECM in that car didn't seem to have any issues. It was a 1984 Cavalier ECM in that car, not the same as you are using, but also OBD1.
    The man who says something is impossible, is usually interrupted by the man doing it.

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