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Thread: Merc 150 four stroke ignition switch

  1. #1
    Ausfish Gold Member 552Evo's Avatar
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    Merc 150 four stroke ignition switch

    Happy new year to everyone. I hope everyone is safe from these tragic bushfires affecting so many people and so much country.

    I’ve installed a 2nd battery with a VSR relay that has an ignition enable/disable wire built in and I would like to find which wire at the ignition switch to cut that into please - if anyone can help ?
    I’ve had a look in the install manual supplied with the engine but that does not show the key switch wiring in detail.
    Below Ive taken a pic of the rear of the switch to show the wires and colours - from the switch the wires extend about 10cm to a plug/socket connector, I was planning on splicing into whichever appropriate wire.
    Any help appreciated,
    Thanks.
    Jamie




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  2. #2

    Re: Merc 150 four stroke ignition switch

    Have a look around your harness before cutting into everything. There is usually a spare 12 volt positive feed somewhere for running additional gauges and the like - just need to use a multimeter to make sure the one you select goes to +12 when the ignition is on. Far better option than cutting into a sealed wire.

  3. #3
    Ausfish Gold Member 552Evo's Avatar
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    Re: Merc 150 four stroke ignition switch

    Thanks Scottar yeah maybe a better idea.
    The only gauge or load that I can think of would be the Vessel View, but I’m guessing that’s a case of it being plugged directly into the merc motor loom ?
    All the rest of the accessories are off a main battery feed.
    I can’t go and have a look now I’m at work on late shift.


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  4. #4
    Ausfish Gold Member 552Evo's Avatar
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    Re: Merc 150 four stroke ignition switch

    Looks like it’s the purple wire that I need to use for the VSR enable ?
    That’s from YouTube for what that’s worth,,,
    I’ll try to find somewhere in the loom hopefully to neatly hook into it, without cutting, fingers crossed.


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  5. #5

    Re: Merc 150 four stroke ignition switch

    Evo, why do you want the VSR to be ignition enabled ? The VSR I have requires the enable wire to be connected to the -ve (negative) it may pay to check if yours in fact requires a +ve. It has been a few years since I installed mine but I seem to recall that a switch could be installed to disable the VSR inline with the enable wire.If you could post a photo of the wiring diagrams you have I or others maybe of further help.
    Frank

  6. #6
    Ausfish Gold Member 552Evo's Avatar
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    Merc 150 four stroke ignition switch

    Thanks Frank,
    The VSR I’m using has 5 wires I total.
    1 for each battery - house and start,
    1 for the ground sensing
    That’s the 3 main wires the 2 below are optional loops that can be cut open to use :
    1 for an external or dash mounted led to show when the relay is engaged.
    1 for a remote enable - this is the one I am querying.

    When I first installed the second battery and the VSR ( without the remote enable used ) the VSR enabled - I heard it click on, and the led on the relay was on. This was with the battery selector switch in the off position.

    I don’t want to have any sort of load on either battery when the boat is packed away. As I understand it with the VSR enabled both batteries are linked, ie one big battery. This situation is fine for charging, but not good for storage - that’s my understanding, I’m happy for it to be explained betterer

    So as a temporary measure I installed a rocker switch to test the setup, and it works. The VSR doesn’t turn on at all unless I have the switch on.
    So I thought it would be best to long term get rid of the switch I added to test the setup and connect the enable wire to the ignition/running circuit.

    Since the installation when I sat back and thought about how I’d be using it, I’ve figured that with the original battery isolation switch that was supplied with the boat, it’s going to be a PIA always changing from position 1 to 2 when I anchor up and soak some baits with the live well running and lights and sounder etc.
    Is this how it’s meant to be used ?
    Or am I meant to leave the switch on the 1/start battery and rely on the VSR to detect the drop and open the link between the 2 ? This doesn’t sound right to me ?

    Anyway sorry for the long story:

    Since last week when I installed it all I’ve found that it seems I should be using a different style of battery isolation switch, an intermediate style switch, like a double pole switch that keeps both batteries separate and the VSR links them as required.

    I hope all this makes sense to someone haha.



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  7. #7

    Re: Merc 150 four stroke ignition switch

    The traditional VSR's I used to simply connect the start battery connection to the output side of the main battery switch so it disconnects from the start battery when the switch is shut down. What I'm not sure of aith the newer digital VSR's that will also monitor the house battery for a charge input is whether they shut down entirely when the start connection is removed or whether they are still monitoring the house battery. Easy enough to connect a multimeter in series with the house connection to test briefly on a low milliamps setting - also connect the negative but not the start battery connection.

  8. #8

    Re: Merc 150 four stroke ignition switch

    Quote Originally Posted by 552Evo View Post
    understanding, I’m happy for it to be explained betterer




    Or am I meant to leave the switch on the 1/start battery and rely on the VSR to detect the drop and open the link between the 2 ? This doesn’t sound right to me ?


    Since last week when I installed it all I’ve found that it seems I should be using a different style of battery isolation switch, an intermediate style switch, like a double pole switch that keeps both batteries separate and the VSR links them as required.




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    Yes - that's what they do.

    Keep your existing battery switch and just add a another cheap key style to switch on your house power provided you have somewhere to mount it. Other than that, yes, there is a blue seas switch that in the first position switches on both the start battery and the house battery separate from each other and in the second position parallels the two.

  9. #9

    Re: Merc 150 four stroke ignition switch

    Jamie, Should I be worried ? your making some sense LOL.
    What you have said sounds OK BUT
    (1) the battery isolators should isolate power from the vsr when "off" ie the battery wires from house and start should through each isolator so there is no drain on either battery when they are "off"
    BTW this will also negate the need to enable / disable the VSR
    (2) Yes the switch for batt. 1 can be left on so that the start battery is auto disconnected from the house (by the VSR) when it falls below a set voltage so that your start battery is not discharged any further so has
    enough charge to start the motor.
    BUGGER I just reread your post, do you have only one isolator ?
    If so I'd be fitting another one, the switches I use are the 1 , 1&2, 2, off (ie 4 position switches) the start switch will allow the start from either battery or both, as will the house switch allow the house to be supplied from either
    battery. The VSR simply joins the two batteries when the "start" battery has enough voltage (after motor start) so both batteries are charging when motor is running. The VSR then disconnects the two batteries when the motor is stopped and the voltage falls far enough due to equipment that's on sounder, lights etc etc
    The wiring on your VSR looks a bit small for the house & start batteries, when the vsr switches the batteries together there can be a heavy current flow from the start battery into the house battery if the house battery is heavily discharged.
    For example my VSR is rated at 140Amps. When night fishing I always run the motor for about 10 mins. when I see the house battery getting a bit low (anything below 12volt)

    I hope I've helped and not confused you further (and you thought you had a long story)
    Frank

  10. #10
    Ausfish Gold Member 552Evo's Avatar
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    Merc 150 four stroke ignition switch

    Quote Originally Posted by scottar View Post
    The traditional VSR's I used to simply connect the start battery connection to the output side of the main battery switch so it disconnects from the start battery when the switch is shut down. What I'm not sure of aith the newer digital VSR's that will also monitor the house battery for a charge input is whether they shut down entirely when the start connection is removed or whether they are still monitoring the house battery. Easy enough to connect a multimeter in series with the house connection to test briefly on a low milliamps setting - also connect the negative but not the start battery connection.
    Thanks again scottar and Frank, all this info is gold, Ive known about this dual battery stuff for years but never really put any thought into how it’s meant to be used and how it works.
    Once I thought about out how it works then I can better understand how it’s meant to be used.
    Originally I thought the idea was promoted to totally separate the start battery, which it only does once a threshold voltage has been reached. That’s what got me thinking I had to do all this switching - to keep the start battery safe during an engine off period.
    Thinking about it further - this optional loop for the enable will not need 12v at all it will need a N/O relay contact,,,
    In my mind - adding a relay is adding a point of failure. So maybe like you say scottar - add a key style isolation switch to be the N/O contact instead. Less chance of failure.

    I’ve already picked up the blue seas “special” switch today on my way to work, so it’s there to be used, I’ll have another think over the weekend.

    Appreciate your help and inspiration fellas.
    Thanks.


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  11. #11

    Re: Merc 150 four stroke ignition switch

    Quote Originally Posted by 552Evo View Post
    Thinking about it further - this optional loop for the enable will not need 12v at all it will need a N/O relay contact,,,
    In my mind - adding a relay is adding a point of failure. So maybe like you say scottar - add a key style isolation switch to be the N/O contact instead. Less chance of failure.




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    Misunderstanding I think. The key type battery switch was to isolate the house load from the house battery as you don't now want it coming off the main start battery switch - regardless, now that you have the Blueseas one it's irrelevant. No need for a relay - the instructions say to connect that cut wire to 12 volts (the correct side of it) . You could do this at the engine ignition or it could even be hooked up to the battery switch output. The current draw of the VSR is minimal and will not be an issue over the course of a normal fishing trip. If you were to leave the batteries switched on for a period of weeks without a charger, they would be flattened however.

  12. #12
    Ausfish Gold Member 552Evo's Avatar
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    Re: Merc 150 four stroke ignition switch

    Ok got it thanks again.


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