Need help w a hourmeter switch on my boat please

Discussion in 'General Electronics Chat' started by Flyboycj84, Apr 23, 2014.

  1. Flyboycj84

    Thread Starter New Member

    Apr 23, 2014
    19
    0
    Hello all.....stumbled across your forum while searching for answers to a prob i have with my boat and the part isnt made any more from the manufacturer. Very basic description here as I am definitely a newb with my basic electrical understanding.

    Here goes:

    The ignition switch has 3 positions: off/on/start. The hour meter is normally hooked up to a 12v post on the ignition switch allowing it to record hours when the ignition is on. The problem is that the hourmeter will record when the switch is ON, and this is a problem because i only want to record motor running hours. So, Chaparral wired something in which the hourmeter is only provided 12v when you engage the spring loaded START position and then have the key in the ON position.

    This fancy item is no longer available for replacement, and cannot be ordered. Strange, I know.

    So what can I wire up/make that will only provide 12v to the hourmeter AFTER the ignition switch is turned to START?

    Ideas appreciated!
     
  2. samuel.whiskers

    Member

    Mar 17, 2014
    95
    2
    How about changing the ignition switch to provide an ACC setting, much like a car?
    Or running the hourmeter off the alternator on the engine??
     
  3. Flyboycj84

    Thread Starter New Member

    Apr 23, 2014
    19
    0
    Good ideas. As for the ignition, i guess the design was made so i dont have to worry about switch position. And short of running new wiring, I dont think theres anywhere in the helm to tap into that has power only when the motors are running.
     
  4. inwo

    Well-Known Member

    Nov 7, 2013
    2,433
    315
    Connect hour meter to electric fuel pump. If it's a carb. motor, electric fuel pump is powered thru oil pressure switch.

    If not, add an auxiliary oil pressure switch. I think they're about $10.

    Here's a BW S369 I have for a spare.
     
  5. Flyboycj84

    Thread Starter New Member

    Apr 23, 2014
    19
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    Hmm...that could work. The motor is an EFI, so fuel pump runs in ON position, so that's out. Thanks!
     
  6. inwo

    Well-Known Member

    Nov 7, 2013
    2,433
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    That's the fool proof way. Meter only runs while engine is running.
     
  7. inwo

    Well-Known Member

    Nov 7, 2013
    2,433
    315
    Here's a hard way if you have a standard warning light.:D

    A wire from the sensor side of the warning light, could drive the base of an NPN transistor with hour meter in collector circuit.

    Loss of oil pressure shunts base drive, turning off hour meter.

    Should only need a 2N222 and a 470ohm or so base resistor.
    Warning light remains connected as is.

    [​IMG]
     
  8. inwo

    Well-Known Member

    Nov 7, 2013
    2,433
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    Like this................................

    Oops, forgot the emitter. (It's the bottom-NPN)
     
  9. Flyboycj84

    Thread Starter New Member

    Apr 23, 2014
    19
    0
    No warning light, but.....there is a warning horn! Interesting. Also, I went out and multimetered again and found that of the 2 power leads that go to the hourmeter......they both measure 12v when the switch is ON, but one of them measures around 5-6v when the motor is running. Not sure how this helps though.
     
  10. inwo

    Well-Known Member

    Nov 7, 2013
    2,433
    315
    If it's a one-wire oil pressure switch that is normally at ground, then goes open with pressure it should work.

    Unless load is high impedance.:( There should be a fix for that though.:D

    Wait for other input however. I'm half asleep.
     
  11. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
    428
    ont thing forgotten, if you turn on the ignition switch without starting the engnes, you can damage the ignition, burn points, coil, ect. as well as charging system damage. if you want to run electric things without the engine running, take them off the ignition circuit.
     
  12. wayneh

    Expert

    Sep 9, 2010
    12,127
    3,048
    FWIW, on my boat I use a small, cheap, Briggs and Stratton hour meter that triggers off sensing a current in one of the spark plug wires.

    My boat's computer also logs engine hours but I cannot get at the number without dealer equipment. That logging is "ignition on" hours. So it exaggerates engine hours. BUT, the computer turns off the ignition after a few minutes if the engine is not running, so it's not so bad.

    Point is, maybe your boat's computer also turns off your meter after a while if it knows the engines isn't running.
     
  13. Duane P Wetick

    Active Member

    Apr 23, 2009
    408
    19
    On my boat, key-Off shuts down the engine and disables the hourmeter, which gets it power from the tachometer. This is the logical way to determine if the engine is running; 0 rpms means engine(s) are shutdown. I don't why you would want to wire the hourmeter any other way.
    Note: AlfaCliff is correct, leaving the key on will run your batteries down (I've done it!). If you want to run accessories with the engine(s) off, re-wire them off the ignition circuits.

    Cheers, DPW [Everything has limitations...and I hate limitations.]
     
    Last edited: Apr 25, 2014
  14. wayneh

    Expert

    Sep 9, 2010
    12,127
    3,048
    Because the key can be on, hour meter counting, without the engine running.
     
    inwo likes this.
  15. Flyboycj84

    Thread Starter New Member

    Apr 23, 2014
    19
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    So the Chaparral guy I spoke with said that one of the wires going into this "box" pulses when the tachometer is powered. The pulsing wire then apparently "tells" the main power lead to feed 12v to the hourmeter. They are checking on a replacement frm the hrness maker and brainstorming on their end. I guess we'll see! Thx for the responses.
     
  16. inwo

    Well-Known Member

    Nov 7, 2013
    2,433
    315
    And the other one is 0 or 12vdc?

    Is meter connected thru the device you mention in first post?
    Is device not working?
     
  17. Flyboycj84

    Thread Starter New Member

    Apr 23, 2014
    19
    0
    Correct, device is not working. When motor is running one wire is still a full 12v, and the other is reduced to 5-6, which ive now learned is pulsating from the tach.
     
  18. inwo

    Well-Known Member

    Nov 7, 2013
    2,433
    315
    Is the device potted? Or do you have access for repair?

    It could just be single transistor and capacitor to make an integrator.

    The pulses would be leveled out (thru diode and resistor) then routed to base of transistor that pulls the low side of hour meter to ground.
     
  19. debe

    Well-Known Member

    Sep 21, 2010
    946
    184
    This circuit is a Gas safety valve & should do what you want. It senses ign pulses to activate the relay. No ign pulses it turns off. Think I may have drawn the 2 transistors wrong. The BC337 is NPN & the BC327 is PNP.
     
  20. Flyboycj84

    Thread Starter New Member

    Apr 23, 2014
    19
    0
    Ummm, wow. You guys rock. I'm not gonna lie, I now know how it feels when laypeople hear my coworkers and I talk flying (airline pilot). You have provided what I need as far as a diagram goes. If the Chaparral guy can't help me out, I will definitely investigate soldering up this circuit. I think I can decipher most of that diagram with the Google machine and my electrician neighbor. Thanks!
     
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