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DC Voltage Panel sometimes shows incorrect voltage

Discussion in 'Cabo Yacht' started by CSkipR, Dec 4, 2013.

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  1. CSkipR

    CSkipR Member

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    On the DC side of my electrical panel sometimes it shows the correct voltage of 26v with charger on for both the engine or house and other times it will show anywhere between 26v-80v. I don't really think it is accurate when that happens but cannot figure out why. Its been doing this for the past two years. Maybe something defective on the panel, not sure. Any ideas.
  2. Capt Ralph

    Capt Ralph Senior Member

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    I assume it's a digital volt meter? Bad DC negative connect.
    ,rc
  3. CSkipR

    CSkipR Member

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    RC,
    Yes it is a digital gauge in the electrical panel showing voltage and amperage. Its only the voltage that fluctuates a bunch. Should I look for a loose negative connection behind the panel?
  4. Capt Ralph

    Capt Ralph Senior Member

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    As nice and high tech digital gages are, They get flaky. The first thing to check would be the DC negative lead from the meter. Probably some light gage wire and a big crimp making a bad connect. If your panel is back lighted, or a close DC- bar, make sure you have a good connect to it. While the panel is open, try to get a mfg, model or part number off the meter. If problem comes back, start shopping the web with this info.
    ,rc
  5. CSkipR

    CSkipR Member

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    Will check tomorrow for any loose connections, etc.
  6. Chasm

    Chasm Senior Member

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    Could also be a charger defect!
    So check with a known good meter before you start to hunt wires. ;) Measure both DC and AC voltage, you should not have any significant amount AC on your batteries.

    Obviously you'll want to recreat the fault condition, when the charger is operating and the installed meter shows a suspect value. But: Take a good look at you batteries first, if this is actually a charger defect they could fail spectacularly.
  7. Capt J

    Capt J Senior Member

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    Check your charger. I replaced a lot of those Newmar chargers that Cabo used. I recently had one go bad on the sunseeker. It was letting 68 volts AC out and stuck in full charge mode. It cooked the entire set of 11 month old AGM batteries. Also, there are fuses on the backside of those displays and sometimes they didn't fit tight and caused the displays to do weird things as well.
  8. CSkipR

    CSkipR Member

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    Thanks although I don't think it is the charger. When this occurs and I turn off the charger the digital panel display will still show a high voltage. If it was the charger I would think when its turned off the voltage would drop back to approximately 24v.
  9. Capt J

    Capt J Senior Member

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    No, the DC voltage will stay high for a little while until the excess voltage/energy is used. Go feel the batteries and feel if they're hot or smell. Then put a multimeter on them and see where you're at on DC. Then check them with the multimeter on AC. You don't want AC current on your batteries, but if a diode goes bad in the charger it will leak through. AC voltage will drop off pretty quick as batteries cannot hold AC power.
  10. Capt Ralph

    Capt Ralph Senior Member

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    Chargers have been known to drive people nuts. They have a point. An intermittent diode?? anything is possible. But you state the meter reads these bogus high readings when charger is off.
    If I remember, you run your gen-set most of the time. Do you run the charger when on genny? does the volt meter go high while off the dock?
  11. Capt J

    Capt J Senior Member

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    On the Cabo's, you really should/almost have to run the charger all of the time. If you're running at cruise with the generator going, it will charge the house batteries, but usually not enough.
  12. CSkipR

    CSkipR Member

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    RC & Capt J,
    Yes I run the gen and charger whenever I'm out in the boat. Whether the voltmeter goes high when away from dock I honestly don't know or can't remember. Age thing.. Will flip breaker off at dock next time and check.
    Skip
  13. Capt J

    Capt J Senior Member

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    When it is showing high voltage, put a multimeter on the wiring on the backside of the gauge and check it. Also check it on ac voltage. If you're showing proper voltage the gauge is bad and it's an easy change.
  14. CSkipR

    CSkipR Member

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    Voltage Reading on DC Panel

    Capt J,
    I checked the batteries with and without the charger on and everything on the battery side seems good. Also checked them using the ac side of tester and did not get any voltage showing. I assume checking for ac voltage you just turn the meter over to ac and put meter wires on terminals. Temperatures were all about the same 72.
    Tried checking voltage on back of red digital gauge but there is all kinds of diodes, (some type of electronic board) and not any way to measure voltage that I saw.
    Skip
  15. Capt Ralph

    Capt Ralph Senior Member

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    You have a coffee pot on your ship? DOD issue (non flavored or fancy)?
    Think it's time for a visit.
    I'll bring all the proper hammers, I promise.
    If you can re-create the symptom, I can make it go aweigh (or fix it).
    ,rc
  16. CSkipR

    CSkipR Member

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    Digital DC Voltage gauge

    RC,
    Certainly got a coffee pot on board although this issue isn't worth your time. Its been like that for 2 years. I'm convinced its the gauge. Thanks for the offer but lets make it for a larger issue. I'm sure one is right around the corner because it is a boat.
    Skip
  17. Capt J

    Capt J Senior Member

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    Then just replace the part on the electrical panel. It's very good to know what your DC voltage is.
  18. Capt Ralph

    Capt Ralph Senior Member

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    Gee, Getting harder to find a cup of coffee.
  19. Capt J

    Capt J Senior Member

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    Hey. Coffee's getting expensive these days!
  20. CSkipR

    CSkipR Member

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    It looks to be very expensive.