Forums General Discussion Large resistor/fuse/circuit breaker on W60

This topic contains 9 replies, has 6 voices, and was last updated by  john stevenson 8 years, 5 months ago.

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  • #68295

    Seawater
    Participant

    My W60 has a large resistor looking thing between the batteries and the starter. It is on the port side near the transmission. Does anyone know what this thing is for?

    My engine has never cranked over very well, always grinding over slowly even with new batteries with a fresh charge. I have heavy 00 or 000 welding cable to the engine and a good ground.

    Today I bypassed it, and the engine cranks like it ought to, and starts much quicker than it did.

    Any help would be appreciated.

  • #76953

    petedd
    Participant

    Sounds like a fuse. If you remove it, put an appropriately sized
    switch in-line. If you have ever had a starter stick, you know that it
    can start a fire in pretty short order so having a way to disconnect the
    circuit should be available.

    Pete

    On 3/30/2011 8:26 PM, Seawater wrote:

    My W60 has a large resistor looking thing between the batteries and the starter. It is on the port side near the transmission. Does anyone know what this thing is for?

    My engine has never cranked over very well, always grinding over slowly even with new batteries with a fresh charge. I have heavy 00 or 000 welding cable to the engine and a good ground.

    Today I bypassed it, and the engine cranks like it ought to, and starts much quicker than it did.

    Any help would be appreciated.


    Walter
    SV Madness
    P424 Hull #1

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  • #76954

    Seawater
    Participant

    Thanks, I have never had that unpleasant sounding experience, and hope not to.

    I was looking for some other info last night and found a part number for a shunt resistor. It does make sense that since I have a ammeter (non- functional, replaced by link 2000 system) that ammeter would have a shunt. It could also act as a fuse.

    Also, there are two push buttons next to this think on the engine, that I think are some sort of circuit breaker for the starter, I have a vague recollection of one of them popping once, and it took a bit of trouble shooting before I pressed one ot the buttons and restored the desired function (cranking, as I recall). Maybe they use the shunt resistor to measure the current flow too, but I don’t know how they would interrupt the current if they are not in series with the power flow. And, why would there be two?

    Sweet mysteries of life.

  • #76955

    quent
    Participant

    Hi Walter-
    We have a W-58, not a W-60, but they are probably wired in a similar manner.
    The device with a button is a circuit breaker for the glow plugs. The other device is probably a relay for the starter solenoid circuit. This is required so that the current necessary to engage the starter does not have to go through the key switch or starter button. It could be that one of the connections is not good, and there is insuffient power to fully close the starter solenoid. I’d clean up all these connections and see if that fixes the problem. If that doesn’t work, replace the relay.
    ABYC and Coast Guard do not require or recommend fusing the starter cable because of the necessity to always be able to start the engine. However, the starter should be wired through the main battery switch to allow this circuit to be disconnected. I also fuse the battery bank at a level to protect this unprotected starter cable. I think I have a 500 amp fuse there, which has never blown.
    Regarding the use of welding cable for the starter, Pearson did this on our boat too. Welding cable is inadequate for engine spaces. The insulation will not stand up to oil, fuel, or the engine room temperatures. On Clairebuoyant, the insulation on the red starter cable softened and split lengthwise near the starter. Had the bare conductor touched the engine, we could have lost the boat to fire.

    Quent
    Clairebuoyant, #132

  • #76956

    petedd
    Participant

    On my w58 there were two breakers. One for the starter solenoid and one
    for the glow plugs if I remember correctly.

    On 3/31/2011 5:12 AM, Seawater wrote:

    Thanks, I have never had that unpleasant sounding experience, and hope not to.

    I was looking for some other info last night and found a part number for a shunt resistor. It does make sense that since I have a ammeter (non- functional, replaced by link 2000 system) that ammeter would have a shunt. It could also act as a fuse.

    Also, there are two push buttons next to this think on the engine, that I think are some sort of circuit breaker for the starter, I have a vague recollection of one of them popping once, and it took a bit of trouble shooting before I pressed one ot the buttons and restored the desired function (cranking, as I recall). Maybe they use the shunt resistor to measure the current flow too, but I don’t know how they would interrupt the current if they are not in series with the power flow. And, why would there be two?

    Sweet mysteries of life.


    Walter
    SV Madness
    P424 Hull #1

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  • #76957

    quent
    Participant

    Hi Pete-
    That would probably be a good idea. The Westerbeke wiring diagram shows one 20 amp breaker servicing both the glow plugs and the starter circuits.
    Quent

  • #76958

    RichCarter
    Participant

    I think it’s the shunt resistor for the ammeter. It should be between the alternator and starter. The batteries should connect to the starter, not alternator.

    Rich

    On Mar 30, 2011, at 10:26 PM, “Seawater” wrote:

    My W60 has a large resistor looking thing between the batteries and the starter. It is on the port side near the transmission. Does anyone know what this thing is for?

    My engine has never cranked over very well, always grinding over slowly even with new batteries with a fresh charge. I have heavy 00 or 000 welding cable to the engine and a good ground.

    Today I bypassed it, and the engine cranks like it ought to, and starts much quicker than it did.

    Any help would be appreciated.


    Walter
    SV Madness
    P424 Hull #1

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  • #76966

    Seawater
    Participant

    Thanks, all.

    It was indeed a shunt resistor for the ammeter. I don’t see the reason for passing the starter current through the resistor, so I am bypassing it.

    Thanks for the heads up on the welding wire. I used the term loosly to mean 00 fine stranded wire. I will have to see if it is marine graded.

    The circuit breakers seem to be for the pre-heaters and the alternator, but I have not confirmed.

  • #76967

    madsailor
    Moderator

    Hi Walter,

    The reason the shut is there is because on a normal engine installation all
    power is tapped from the starter. Marine installs are different in that
    there are two main circuits, engine and ship’s power. For true current
    draw, move the shut to a single ground point. Otherwise, move it to the
    line that powers the dc panel.

    The shut should have very little resistance. Negligible when considering
    ship’s loads.

    Bob

    I’m not being terse. This is from my mobile.
    On Apr 1, 2011 8:09 AM, “Seawater” wrote:

    Thanks, all.

    It was indeed a shunt resistor for the ammeter. I don’t see the reason for

    passing the starter current through the resistor, so I am bypassing it.

    Thanks for the heads up on the welding wire. I used the term loosly to

    mean 00 fine stranded wire. I will have to see if it is marine graded.

    The circuit breakers seem to be for the pre-heaters and the alternator,

    but I have not confirmed.


    Walter
    SV Madness
    P424 Hull #1

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  • #76968

    john stevenson
    Participant

    If indeed the shunt is producing significant resistance on the starter
    circuit, it must be defective. As Bob wrote, the resistance should be
    negligible, unless the shunt is broken (or it really isn’t a meter shunt).
    I’d just throw it away.

    On Fri, Apr 1, 2011 at 9:04 AM, Robert Fine wrote:

    Hi Walter,

    The reason the shut is there is because on a normal engine installation all
    power is tapped from the starter. Marine installs are different in that
    there are two main circuits, engine and ship’s power. For true current
    draw, move the shut to a single ground point. Otherwise, move it to the
    line that powers the dc panel.

    The shut should have very little resistance. Negligible when considering
    ship’s loads.

    Bob

    I’m not being terse. This is from my mobile.
    On Apr 1, 2011 8:09 AM, “Seawater” wrote:

    Thanks, all.

    It was indeed a shunt resistor for the ammeter. I don’t see the reason

    for
    passing the starter current through the resistor, so I am bypassing it.

    Thanks for the heads up on the welding wire. I used the term loosly to

    mean 00 fine stranded wire. I will have to see if it is marine graded.

    The circuit breakers seem to be for the pre-heaters and the alternator,

    but I have not confirmed.


    Walter
    SV Madness
    P424 Hull #1

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    Regards,
    John Stevenson
    http://www.svsarah.com
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