After running the motor for around 4 hours the tacho cuts out on my 3YM30 Yanmar. If you switch off the ignition switch and then switch it on again the tacho cuts in again but only for a limited time maybe 10/20 mins. This happens as regularly as clockwork every time I have to motor for extended periods. Anyone out there have a similar problem and has solved it?
3YM30 Tacho Problems
- Thread starter nick8489
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Have not seen that with my 3YM30. Is this original equipment(your boat is a newer H33)? I installed mine and it came with a new instrument panel. I don't like the lack of gauges but otherwise have not had a problem. You could rule out the ignition switch as a problem by jumping across. Get a short wire with alligator clips on each end. The obvious first choice is to tighten all the connections on the back of the panel. I am betting it is something to do with that switch.
The tach is usually from the output of the alternator, unless it's direct from the engine. If your batteries are/become full, the regulator may simply be turning off the alternator, thus turning off the tach. I have no idea what kinda charging system you have. Irish tachos are different.
Thanks Ed,
Mine is original equipment on a 2004 H33. Will have a good look at the ignition switch.
Interesting that you should mention this Stu as someone else told me that if the battery voltage get too high, they said over 15V then the tacho on the 3YM30 cuts out. Certainly when it does this on mine it is always when the battery is full. This does seem crazy if true. The local Yanmar guy says that he has not heard of this but then they never know anything electrical.The tach is usually from the output of the alternator, unless it's direct from the engine. If your batteries are/become full, the regulator may simply be turning off the alternator, thus turning off the tach. I have no idea what kinda charging system you have. Irish tachos are different.
My charging is twofold; from the engine altrernator via an aftermarket smart regulator and from 3x80 watt solar panels.
Yes, but
you didn't confirm if your tach IS run off the alternator. The 15V sounds a little nonsensical, since it's not a specific voltage, but rather what the regulator setting is, which could be 15 but that sounds way too high, more like 14.4 for wet cell batteries.
Now that you add the information that you have a hefty solar array, it becomes more apparent, again IF your have an alternator driven tach.
Wanna know? Turn on your fridge if you have one, or all your lights to create a load, and, if you can disconnect your solar for a half hour or so. Once the battery bank says it can accept some juice and the regulator starts charging, the alternator will run and the tach should, too. Please report back.
This is a simple check before ya go doing anything dangerous, like touching stuff!
Also, it's NOT the tach on your engine, it is the WAY alternators work, true for all alternators nothing to do with the engine at all.
This is NOT crazy. This IS true. Geez, if your batteries are always charged, your alternator will never have to work. That's great!
you didn't confirm if your tach IS run off the alternator. The 15V sounds a little nonsensical, since it's not a specific voltage, but rather what the regulator setting is, which could be 15 but that sounds way too high, more like 14.4 for wet cell batteries.
Now that you add the information that you have a hefty solar array, it becomes more apparent, again IF your have an alternator driven tach.
Wanna know? Turn on your fridge if you have one, or all your lights to create a load, and, if you can disconnect your solar for a half hour or so. Once the battery bank says it can accept some juice and the regulator starts charging, the alternator will run and the tach should, too. Please report back.
This is a simple check before ya go doing anything dangerous, like touching stuff!
Also, it's NOT the tach on your engine, it is the WAY alternators work, true for all alternators nothing to do with the engine at all.
This is NOT crazy. This IS true. Geez, if your batteries are always charged, your alternator will never have to work. That's great!
Off Alternator
I don't think that we are on the same wavelength though
The solar array does keep the batteries charged up pretty well full all the time and the fridge and freezer run 24/7. But this is no different to having shore power on permanently. It is illogical that Yamar would have a system where you couldn't read engine revs just because the batteries were fullty charged. Its got to be some other electrical gremlin
Yes the tacho does run off the altwernator.you didn't confirm if your tach IS run off the alternator. The 15V sounds a little nonsensical, since it's not a specific voltage, but rather what the regulator setting is, which could be 15 but that sounds way too high, more like 14.4 for wet cell batteries.
Now that you add the information that you have a hefty solar array, it becomes more apparent, again IF your have an alternator driven tach.
Wanna know? Turn on your fridge if you have one, or all your lights to create a load, and, if you can disconnect your solar for a half hour or so. Once the battery bank says it can accept some juice and the regulator starts charging, the alternator will run and the tach should, too. Please report back.
This is a simple check before ya go doing anything dangerous, like touching stuff!
Also, it's NOT the tach on your engine, it is the WAY alternators work, true for all alternators nothing to do with the engine at all.
This is NOT crazy. This IS true. Geez, if your batteries are always charged, your alternator will never have to work. That's great!
I don't think that we are on the same wavelength though
The solar array does keep the batteries charged up pretty well full all the time and the fridge and freezer run 24/7. But this is no different to having shore power on permanently. It is illogical that Yamar would have a system where you couldn't read engine revs just because the batteries were fullty charged. Its got to be some other electrical gremlin
tach issues
I have a Hunter 45CC the tach is generator driven. Yanmar 4jh
The tach pegs at maximum at times during operation . If I stop the engine and restart it, it operates normally for awhile. If I turn the key off when it is maxed out, the tach goes back to zero, but when I turn the key back on the tach will not move off zero. It does however quiver when I do this. It also quivers right before it maxes out.
I always have some draw on the alternator so I doubt that the alternator is not putting out some amperes for the electronics and autopilot when this happens.
I can not find any bad connections in the wiring.
I have a Hunter 45CC the tach is generator driven. Yanmar 4jh
The tach pegs at maximum at times during operation . If I stop the engine and restart it, it operates normally for awhile. If I turn the key off when it is maxed out, the tach goes back to zero, but when I turn the key back on the tach will not move off zero. It does however quiver when I do this. It also quivers right before it maxes out.
I always have some draw on the alternator so I doubt that the alternator is not putting out some amperes for the electronics and autopilot when this happens.
I can not find any bad connections in the wiring.
Tachy tacho - what's a tacho?
And if it's electrical, the other "usual suspects" are connections, connections, connections.
OK, but don't say we didn't try to explain it to you.
And if it's electrical, the other "usual suspects" are connections, connections, connections.
Jim,
I also get the quivering, just before it drops out to zero and when I switch on again. So sounds like we have a vaguely related problem. Maybe it is a fault in the tacho itself.
Nick Sorry it took so long to respond. I still have not found the problem including checking for loose connections. Took it to Florida from Mass and it created some problems but not too many.
Nick...
A few years ago when my tach acted up (sensor off the flywheel teeth) with erratic, low, or no readings, I checked for loose connections but couldn't find the culprit. Finally pulled each apart, cleaned them with a swab of alcohol, used a needle nose to crimp the female ones tighter, and put them all back together. Haven't had the problem ever since.
A few years ago when my tach acted up (sensor off the flywheel teeth) with erratic, low, or no readings, I checked for loose connections but couldn't find the culprit. Finally pulled each apart, cleaned them with a swab of alcohol, used a needle nose to crimp the female ones tighter, and put them all back together. Haven't had the problem ever since.
I think that this is the wiring diagram for our 3YM30 tachometers: http://diychamber.com/wp-content/up...achometer-Wiring-Diagram-and-Instructions.jpg . The voltage at the "send" connection could be checked when working well, say at idle or some set throttle position. Record that voltage. Next time it acts up check the voltage with the throttle in the same position. If the voltage is the same then the problem "might be" the tachometer. Voltage erratic or very low then back to either: wiring connections, sender unit, or ???
"It is illogical that Yamar would have a system where you couldn't read engine revs just because the batteries were fully charged. "
Might not be logical but it does happen. Our 3YM030 tacho cuts out when the batteries are fully charged. Especially on No1 battery which is also charged by our solar pannel. when I want to look at the rpm I flick the bilge blower on. This slightly reduced the voltage and triggers the alternator to start a charge. Simple. Took me a while to ork it out too. Cheers
Might not be logical but it does happen. Our 3YM030 tacho cuts out when the batteries are fully charged. Especially on No1 battery which is also charged by our solar pannel. when I want to look at the rpm I flick the bilge blower on. This slightly reduced the voltage and triggers the alternator to start a charge. Simple. Took me a while to ork it out too. Cheers
would it be possible to series 1 or 2 diodes on the power supply line to the tachco to drop the voltage by 0.6-1.2V so that it'll always be below max voltage to tachco ?
Wacky Tachy 101
Tachs do not operate on voltage variation like a rescaled volt meter. They are rescaled and refaced frequency meters. They read the ripple voltage fluctuations (AC component in DC current) in either the raw alternator output or from a dedicated tack sender (which is just a coil that gets energized once a revolution by a magnet on the flywheel)
With that said, as long as the ignition is on there should be ripple voltage to sense at the alternator. Even with the regulator turning the alternator completely off (which I doubt but there are lots of weird setup) there should still be residual ripple current coming from the alternator. The magnitude of the ripple (absolute value of the change in voltage) may be an issue. having good connections will tend to enhance the ripple voltage magnitude and give the tack sufficient voltage change to actually measure the frequency and convert that to RPMs.
You can test for ripple with your multimeter by setting it to the lowest (1-5 volts) AC voltage setting and testing between the alternator tack pickup (or + terminal) and ground. There must be an ac component for the tack to read. BTW putting a diode in will only make the ripple voltage magnitude less and make the tack think it is seeing 1/2 the frequency as the diode is taking out the other half (depends on tack model)
The description of your problem sounds like a loose connection due to heat rise. Hot stuff has more resistance than cold stuff. This is especially true of corroded parts. Had the same problem, same symptoms and fixed it just like Dan Johnson did. I have not had a problem for 3 years now.
99.44% of all electrical problems on boats are corroded / loose connections.
Tachs do not operate on voltage variation like a rescaled volt meter. They are rescaled and refaced frequency meters. They read the ripple voltage fluctuations (AC component in DC current) in either the raw alternator output or from a dedicated tack sender (which is just a coil that gets energized once a revolution by a magnet on the flywheel)
With that said, as long as the ignition is on there should be ripple voltage to sense at the alternator. Even with the regulator turning the alternator completely off (which I doubt but there are lots of weird setup) there should still be residual ripple current coming from the alternator. The magnitude of the ripple (absolute value of the change in voltage) may be an issue. having good connections will tend to enhance the ripple voltage magnitude and give the tack sufficient voltage change to actually measure the frequency and convert that to RPMs.
You can test for ripple with your multimeter by setting it to the lowest (1-5 volts) AC voltage setting and testing between the alternator tack pickup (or + terminal) and ground. There must be an ac component for the tack to read. BTW putting a diode in will only make the ripple voltage magnitude less and make the tack think it is seeing 1/2 the frequency as the diode is taking out the other half (depends on tack model)
The description of your problem sounds like a loose connection due to heat rise. Hot stuff has more resistance than cold stuff. This is especially true of corroded parts. Had the same problem, same symptoms and fixed it just like Dan Johnson did. I have not had a problem for 3 years now.
99.44% of all electrical problems on boats are corroded / loose connections.
Wacky Tacky 102
For completeness sake,
An alternator produces AC which is rectified by diodes into ripple DC. The tack output is just the AC before it gets rectified so a voltage 1-1.5 ish above the voltage you measure on the + terminal is what you would expect. The diodes drop the voltage when doing their job.
If the regulator turns off the rotor current completely there is still going to be residual AC at the tack terminal. This is because the rotor has some small residual magnetism even with the motor stopped.
If you have another power source that is not isolated from the alternator I suspect it could be raising the voltage at the alternator high enough to make the residual ripple undetectable by the tack.
SO
For this situation, turning on a load reactivates the alternator and gives you a much stronger (read larger voltage variation in the ripple) signal to the tack. The fact that you see quivering of the needle just before the tack dies that could be either the signal going low enough from a corroded connection or from the solar masking the signal when the alternator shuts off. In either case you are loosing / masking the signal and the tack unit is probably OK
Again, check the AC voltage from the tack terminal. If you compare it before and after (measure it at the engine instrument panel off the back of the tack) you should be able to see the relationship.
BTW switching the ignition on and off causes a voltage pulse which a frequency meter refaced to be a tack would interpret as rotations, very slow rotations, and would there for dutifully report them as a needle bump when the switch is thrown.
If you really want to understand consider that a wind generator (alternator with diodes and makes ripple voltage) can make your tack read RPMs if you just switch on the engine but don't start it. You can only imagine what happens when both are operating at the same time. The fix is really easy though.
Again, 99.44% of all electrical problems on boats are corroded or loose connections. It does not take much to suck up a 1.5 volt signal. One moderately corroded or 12 (that is the number in my start circuit) just OK connections can do it.
For completeness sake,
An alternator produces AC which is rectified by diodes into ripple DC. The tack output is just the AC before it gets rectified so a voltage 1-1.5 ish above the voltage you measure on the + terminal is what you would expect. The diodes drop the voltage when doing their job.
If the regulator turns off the rotor current completely there is still going to be residual AC at the tack terminal. This is because the rotor has some small residual magnetism even with the motor stopped.
If you have another power source that is not isolated from the alternator I suspect it could be raising the voltage at the alternator high enough to make the residual ripple undetectable by the tack.
SO
For this situation, turning on a load reactivates the alternator and gives you a much stronger (read larger voltage variation in the ripple) signal to the tack. The fact that you see quivering of the needle just before the tack dies that could be either the signal going low enough from a corroded connection or from the solar masking the signal when the alternator shuts off. In either case you are loosing / masking the signal and the tack unit is probably OK
Again, check the AC voltage from the tack terminal. If you compare it before and after (measure it at the engine instrument panel off the back of the tack) you should be able to see the relationship.
BTW switching the ignition on and off causes a voltage pulse which a frequency meter refaced to be a tack would interpret as rotations, very slow rotations, and would there for dutifully report them as a needle bump when the switch is thrown.
If you really want to understand consider that a wind generator (alternator with diodes and makes ripple voltage) can make your tack read RPMs if you just switch on the engine but don't start it. You can only imagine what happens when both are operating at the same time. The fix is really easy though.
Again, 99.44% of all electrical problems on boats are corroded or loose connections. It does not take much to suck up a 1.5 volt signal. One moderately corroded or 12 (that is the number in my start circuit) just OK connections can do it.
Tach problems it's not
The output of the alternator is based on battery acceptance: when they're full, like a jug of water, they will simply NOT take any more charge. Period. So charging stops, even though the alternator is still spinning.
So, please, first understand how alternators work and that your "tach" works off your alternator, based on the input from the other skippers with boats like yours. Second, instead of wondering about it, unless your boat's on the hard and you're waiting for spring, go to your boat and then come back online and tell us that you really have checked all the connections and placed a load on your electrical system to assure that the alternator HAS to put out some amps and, hence, obtain a reading.
It also appears that you do not have an external regulator, so your internal alternator regulator is a tapering charge one, consistent with what you are telling us about its behavior. With your solar system your batteries are almost always full. And even with your 24/7 fridge load, your INPUT exceeds your output. That's great. As previously suggested, then only turning on your fridge won't produce the load required, so disconnect your solar panels for a while.
We're here to help and hope that you can implement some of the input provided by many skippers to see if it works for you.
If it was my boat? I'd wire the solar system so that when I needed the tach I could turn off one or more panels so the alternator would HAVE to work. Nothing in charging lost by doing it that way.
You could perhaps consider the advice being given to you and work on that information. Reducing output voltage from an alternator will simply make it harder to charge your batteries, which makes absolutely no sense. Diodes were the old "isolators", a 1960 technology which was determined to be counterproductive to battery charging 40 - 50 years ago. Anyone who knew anything about electrical systems simply ripped them out of their boats.
The output of the alternator is based on battery acceptance: when they're full, like a jug of water, they will simply NOT take any more charge. Period. So charging stops, even though the alternator is still spinning.
So, please, first understand how alternators work and that your "tach" works off your alternator, based on the input from the other skippers with boats like yours. Second, instead of wondering about it, unless your boat's on the hard and you're waiting for spring, go to your boat and then come back online and tell us that you really have checked all the connections and placed a load on your electrical system to assure that the alternator HAS to put out some amps and, hence, obtain a reading.
It also appears that you do not have an external regulator, so your internal alternator regulator is a tapering charge one, consistent with what you are telling us about its behavior. With your solar system your batteries are almost always full. And even with your 24/7 fridge load, your INPUT exceeds your output. That's great. As previously suggested, then only turning on your fridge won't produce the load required, so disconnect your solar panels for a while.
We're here to help and hope that you can implement some of the input provided by many skippers to see if it works for you.
This is simple denial. Tachs working off alternators are a reality. In fact, most people work their house banks between 50% and 85% of charged, except for the weekend warriors who keep their boats plugged in all the time. OR folks who are very smart and have good sized solar arrays that keep up with their electrical demand. Most of the time the trick is to know how to recharge banks, not always having more juice than you need.
If it was my boat? I'd wire the solar system so that when I needed the tach I could turn off one or more panels so the alternator would HAVE to work. Nothing in charging lost by doing it that way.
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