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  1. #1
    Join Date
    Sep 2010
    Nova Scotia

    Extending Starter 12 VDC Terminal Capacity

    I had some unexpected trouble connecting my boat starter up after having it overhauled. The new 12 VDC battery post wasn't long enough for all the cables. Too many lugs and not enough space. Note this is for a boat stern-drive, so there are 4 cables. A heavy one from the battery, a slightly lighter one from the starter, another for the engine electrics and yet another for the electric pump that runs the stern-drive trim hydraulics.

    For some reason, the new solenoid terminal stud is too short. I can get the nut on, but not far enough. Even if I don't use the lock-washer, the stud isn't quite flush with the top of the nut, and it really ought to be at least 1.5 threads proud.

    I went back to the place that did the rebuild and they checked all their stock and no luck there. All were the same... too short. I then visited another starter/alternator shop and found out they stopped selling extenders some 10 to 15 years ago. No luck at the auto-parts store either.

    An internet Search did find one, but from some company I never heard of and a little pricey too.

    I had some thought of only installing a single wire and using a remote terminal block for the rest of the connections, however the engine wiring harness would have to be modified, and I didn't want to start cutting and splicing wires.

    So I decided to make one. I'm not sure how it will hold up with brass, copper and steel (dissimilar metals in a salt air environment), but the nut is steel and the old one showed only minor surface rust and it had been in use for 28 years. And there's something about why bronze is used vs. brass, but I can't remember. Anyway, it isn't being used under water.

    Below is a picture of the extender. I made it from an old brass pipe fitting and threaded the inside to fit a copper stud the Starter Overhaul guy gave me. A steel split pin is used to keep the two parts from turning.

    Here it is installed. You can see how I can split up the cable lugs at the two places shown at the arrows. For clarity I havn't shown the flat-washers or lock-washers.

    I hope it will work, and by that I mean I hope it doesn't corrode prematurely or vibrate loose. I am thinking of using lock-tight, but even with the blue stuff, it might come back to haunt me someday if I need to take things apart. it's a difficult spot to get to; down in the bilge.

    “A prudent person profits from personal experience, a wise one from the experience of others.”

  2. #2
    Join Date
    Aug 2002
    Through the Darien Gap
    I think I would have been inclined to fit a terminal block close by and modify the loom.

    Attached Images Attached Images
    Steve Brown

    CRC Regional Rep - East Anglia

  3. #3
    Join Date
    Sep 2010
    Nova Scotia
    Yes, Steve that is no doubt the best solution, but I compromised and fitted my adapter. It went on tight and I have confidence in it now that I've fitted it.

    Darn wring loom. Molded rubber boots over the terminal lugs... didn't really want to cut them, but I could have. I'm still a solder and heat shrink guy (or better yet, hermetic seals), and on old wiring one does run the risk of wire corroded enough to resist soldering. I do detest the simple crimp.

    I did look at a short battery cable with lugs at each end at the auto-parts store. Cheaply made, with crimped ends. Very thick lugs and would no doubt corrode very quickly. Suspect I would do better from a Marine Supplier.

    In hind sight I think I could have bought a Mercrusier solenoid with the longer terminal stud. Looking at pics on Ebay, it looks like the OEM has the longer stud, but the aftermarket doesn't. And of course the OEM is more expensive, but being merely a solenoid, it's not that bad.

    But I didn't know that then. My initial thoughts only went as far as buying a new starter, and they are atrociously expensive for an OEM one, and although the aftermarket ones are very cheap, quality could be a concern, and that stud still looks short.

    So I'll go with my adapter for now and hope for the best.

    Thank-you for your response.

    “A prudent person profits from personal experience, a wise one from the experience of others.”

  4. #4
    Join Date
    Jan 2009
    Dronten, the Netherlands
    And just cover the terminals with a good coat of Tectyl or non-Naphtha, you'll be fine
    BR Theo
    Not for the faint hearted, not for the shy...

  5. #5
    Join Date
    May 2004
    Stainless stud extenders any good?
    Pro Cobra Builder

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    OEM style stainless SIDEPIPES

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