Alternator output

Discussion in 'Instruments / Avionics / Electrical System' started by N804RV, Oct 2, 2019.

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  1. Oct 2, 2019 #1

    N804RV

    N804RV

    N804RV

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    I have a Kohler style 20amp alternator with an external rectifier/regulator in the Sonerai. I installed an alt. warning light/circuit and removed the analog volt meter to make room for a G-meter.

    The old analog volt meter showed about 14.5vdc inflight. But, the alt. warning light indicates an occasional over voltage condition.

    I put a digital volt meter across the battery terminals and went flying. It shows 15.3 - 15.4vdc when the over volts condition is indicated. Apparently, the alt warning circuit's over-volt threshold is set to 15.2 volts.

    My question: How high is too high? I've heard that automotive type charging circuits can see as high as 16vdc.
     
  2. Oct 2, 2019 #2

    Daleandee

    Daleandee

    Daleandee

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    My Cleanex uses a Yanmar 20 amp dynamo (PM alternator) with an external regulator. My charging voltage usually reads 14.7-14.8 after take-off. This works well with my Odyssey PC 680 battery as they recommend charging at 14.4-14.7 or float charging 8-10 hours at at 13.6. Most automotive alternators that I've checked lately will charge between 13.8-14.2.

    Not sure what battery you are using as that will have a great deal to do with the charging rate. I can't answer your question for you but for me, yes, 16.0 is much too high. 14.8 is the limit I like but that is what works best in the system I have. If you have one of the newer technology batteries ... everything above is incorrect.
     
  3. Oct 3, 2019 #3

    Dan Thomas

    Dan Thomas

    Dan Thomas

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    Check the grounding of the regulator/rectifier unit. A poor ground gives the regulator a lower voltage reference and it will increase the output to compensate.

    Otherwise, the unit might be shot.
     
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  4. Oct 11, 2019 #4

    N804RV

    N804RV

    N804RV

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    Good call Dan! Put a new rectifier/regulator on it today. Took all of 10 minutes. Verified the case-ground was adequate. 1.8 hours flight time today with no over-volts warning. Little digital meter showed pretty steady 14.4vdc.
     

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