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36 convertible electrical issue

Discussion in 'Luhrs Yacht' started by Nick Khoury, Jun 13, 2020.

  1. Nick Khoury

    Nick Khoury New Member

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    New to forum. I just purchased a 2004 36 convertible. Has 3126 cats and having electrical problems.
    1. Port engine started intermittently giving start up issues. Now it's always. When in run position voltage gauge shows 9 to 10 volts and clicks when trying to start. Checked batteries they are a year old and show 1275 cca when tested at two separate places. Cleaned connections and still doing same problem. I tried using parallel with starboard running and still not enough. I jumped batteries together and then use parallel and it will start. Next I'm going to check connections to ground from battery but I'm hanging hard time tracing ground path from battery because they go under generator and I can't see behind. Any suggestions?
    2. Other issue is with AC and DC panel when the battery charger is on port side dc panel works fine. If you shut Ac load off it kills dc side. Again batteries were both tested and are good. I didn't think Ac side and DC were connected in any way?
  2. JW Holt

    JW Holt New Member

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    Just for fun, buy a new battery and try it on one engine. I have had a few that have shown good on a snap on tester but the load was right on the line and the engine didn’t like it.
  3. Capt Ralph

    Capt Ralph Senior Member

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    What kind of battery tester? Lil thing or a real big carbon pile tester.
    Ohm out the cables. You could have a bad cable somewhere.
  4. Nick Khoury

    Nick Khoury New Member

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    West marine used the little tester handheld. I didn't trust it so went to O'Reilly's and they used the larger bench tester both came back good. I'm doing ohm on ground starting from batteries to engine. It's very hard to see because from batteries it goes under generator and I'm having hard time following. I looked at wire schematic and it shows from batteries to engine. I would like to know which ground goes directly back to battery because I see one above the oil pan on block. And another in bell housing by transmission going to back of starter?
  5. Capt Ralph

    Capt Ralph Senior Member

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    The negative and positive leads on the starter comes from the battery directly. Any cables on the block should only be for bonding and not battery negative like on your car. I recall a box above the starter that sends + & - to the ship.

    Remember, this is a boat and not a car or truck. There are large differences in how batteries and DC lines are run.
  6. Capt J

    Capt J Senior Member

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    If that all sounds good, it sounds to me like you've got a bad starter, or something far worse going on in the engine. First see how hard it is it bar the engine over. Secondly when this happens, tap the starter with a few moderate whacks with a hammer and then see if it starts. Quite honestly, just hiring a good mechanic will save you loads of time, frustration and money.
  7. Pascal

    Pascal Senior Member

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    Confused about this part of your post : “I jumped batteries together and then use parallel and it will start.”

    which batteries did you “jump” together? Paralleling batteries should be the same thing, connecting the port and Stbd batteries together
    Can you describe your set up ? How many batteries, what size, connected to what?

    In addition To the starter, there could be an issue with the battery switch as well
  8. Nick Khoury

    Nick Khoury New Member

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    It's almost embarrassing to post the solution that fixed everything. I started ohm testing and tracing from starter to grounding block to batteries and everything checked out. I put the volt meter on back of starter and had 12.7 volts and turned starter switch into on position and voltage dropped to 5 volts. Luckily I heard something arching in the electric box above starter. I had to disassemble couch to lift hatches so I could lift lid of electric box on engine. Then I went back to starter switch and when put into on position voltage on back of starter only dropped 1 volt. It started right up and no problem. On the back of the lid of electric box was a laminated wire schematic folded in half and plastic had melted and that was squishing wires in electric box and causing a short. Put the lid back motor fires up with no problems. Everything runs perfect. If you have 3126 cats check the electric box I don't know if caterpillar put this in or previous owners mechanic but it was the problem.

    One other question what size battery should be on each motor? The previous owner has 8d 1335 cca from Napa which are not marine batteries they are truck batteries. I'm asking because I ran the windlass and it drained the batteries causing the parallel to be needed to restart. Once I ran charger for hour it charged it back.
  9. Nick Khoury

    Nick Khoury New Member

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    Read below my fix of the problem you'll get a good laugh. Previous owner had two 8 d 1335 cca from Napa. These are truck batteries and not marine. I've read some different specs but would appreciate if anyone knows for sure what cca batteries should be used? Of course I'm replacing with marine 8d.
  10. Capt J

    Capt J Senior Member

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    An 8D is plenty sufficient for a 3126 starting battery. Glad to hear you found the issue. Sounds like you have a bad battery. How long did you run the windlass for?
  11. Nick Khoury

    Nick Khoury New Member

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    Capt j I ran it for fifteen seconds. Then was to close to another boat picked back up for another 15 seconds and dropped it back for second time but I couldn't bring up battery would drop down to 9 volts so I manually pulled it up. Charged it for about an hour and I can start motors but I'm thinking the 8d truck battery from Napa doesn't have same amp hour reserve that a marine battery has.
  12. Capt J

    Capt J Senior Member

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    It should have plenty of reserve to do that. Your batteries are just passed their expected life.
  13. Pascal

    Pascal Senior Member

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    An 8D should be fine, truck or marine. have you checked the water level?

    personally I can’t imagine why anyone would even think of raising anchor without the engines already started... it s a common sense safety issue.

    why did the cover on the box melt? And how can melted plastic squish wires causing a short?
  14. chesapeake46

    chesapeake46 Senior Member

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    More likely a loose connection caused the heat that caused the melting that was the result of the problem.

    Possibly 1/2 was fixed by PO ?
  15. Nick Khoury

    Nick Khoury New Member

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    yes checked water level it both batteries were good
    I don't know what kind of idiot sets and pulls an anchor without engines running but that's not me. The drop in voltage when I pulled it up the second time caused port main to shut down and then I had to parallel to restart. Pulled anchor up by hand. When I got back to dock an hour after with charger running re charged battery.
  16. DOCKMASTER

    DOCKMASTER Senior Member

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    Good to hear you are not running the windlass without the engine running. But if the engines were running why didn't the alternator charge as you were running the windlass? Maybe not enough charge from it at low RPM? I would do a complete check of your entire DC system. How much are your alternators putting out? Did you find the date code on the batteries? How old are they? It is possible the previous owner let the battery water level get low then added water getting it ready to sell. This can cause batteries to read fine but have no reserve. Also, do you have a generator with an A/C fed charger hooked up? Maybe you have something else drawing down your batteries? DC Refer, lights, etc?
  17. Pascal

    Pascal Senior Member

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    Your alternator should have recharged the battery, what is the voltage charger off but engine at high idle?

    the windlass shouldn’t cause a drop big enough to stop the engine. It sounds like the alternator isn’t charging

    this is why I hate how builders try to save a buck and use house one of the engine batteries to power house loads. Each Engine and generator should have it own bank plus one for the house loads. Check that alternator
  18. d_meister

    d_meister Senior Member

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    Sounds like the correct diagnosis to me, except the part of it being fixed. I would disconnect the cables at the batteries, and then dismantle and clean up all of the connections in the box. Going over all of the connection points in battery-direct wiring would be good, too.Be sure the wires aren't "Hot". There are often no fuses in short primary wiring circuits. If a wrench accidentally bridges connections; it's often welded in place.
    P.S. I think muscling an 8D battery out of the boat and around town to be tested shows admirable dedication :)
  19. chesapeake46

    chesapeake46 Senior Member

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    Good exercise though !!
  20. Nick Khoury

    Nick Khoury New Member

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    Agreed this is the first boat I've owned that runs house through motor battery. I'm going to check alternator output.