defective coil

[hanleyclifford]

Sorry Hanley but that doesn't answer the questions:

1. If true, why Steve's and not mine? We have virtually identical setups and virtually identical usage, his failed (assumed "drilling") and mine hasn't. If this were a real issue, wouldn't I have experienced the same?
2. You said I suspect never get their batteries up to full charge where the alternator can "drill" the system at full voltage allowed by the regulator for any appreciable time. This assumes a variable voltage output from the alt/reg when in fact it's the amperage that varies. The voltage strives to remain constant. Man, I can't even believe this discussion has come up again.
3. Are you suggesting ANYONE running their engine with fully charged batteries risks coil damage from the alternator? Or that we don't see the damage because nobody runs their engine very long with fully charged batteries?
4. How much run time with fully charged batteries does it take to damage the coil? Steve didn't mention a time span but I did, 9 hours continuous with a 100 amp alternator capable of putting out 50 amps @ 2000 RPM at ~14.1 volts constant.
5. What about a cross country auto trip? Their batteries will be fully charged early on, their charging system is the same as ours and they'll be running for hours upon hours, day after day. Do their coils get "drilled"? My folks' 1960 Mercury station wagon didn't have coil problems in 1964 on such a trip. Six weeks of daily extended operation.

This isn't complicated. You suggest running for an as yet unspecified time with fully charged batteries can "drill" a coil to failure and I'm not buying it without some solid support.

My only reason for challenging the premise is to maintain solid information on the forum. If this is true it should be supported. In fact I'll open it up: Does anybody have experience or a reference in support of the premise? If it's true it's new territory to me and I'd like to learn more.

#1 - No such thing as "identical" systems. #2 - The operative word here Neil is "strives", but it never really gets there throughout the system until the batteries are satisfied. #3 - Not a risk if you keep voltage at low levels at coil+ no matter what state of charge the batteries are at #4 - 14.1volts alternator output is probably good for you for a motor Pacific crossing, but maybe not for others. #5 - we're talking EI here, with fancy coils. In short, the tolerance of a coil for high voltage is hard to predict or calculate, but a good bellweather is to put your hand on it at cruise rpm after a few hours running. If you can't do it, be afraid - be very afraid.

[ndutton]

Steve's and my system are as closely matched as systems can get yet he experienced a widely different result than me. Also, are you suggesting motoring in the Pacific is different than elsewhere? That's why Steve's failed and mine didn't? If Steve moved his boat to the West Coast he wouldn't have had the problem? Sorry, this isn't the solid support I was hoping for.

Let's try one single question based on your premise that begs a simple numerical answer: What is the expected voltage difference at the coil before and after the batteries are charged fully, a voltage difference that I can actually measure on my boat?

And with that, I'm done. The last word is all yours.

[hanleyclifford]

Steve's and my system are as closely matched as systems can get yet he experienced a widely different result than me. Also, are you suggesting motoring in the Pacific is different than elsewhere? That's why Steve's failed and mine didn't? If Steve moved his boat to the West Coast he wouldn't have had the problem? Sorry, this isn't the solid support I was hoping for.

Let's try one single question based on your premise that begs a simple numerical answer: What is the expected voltage difference at the coil before and after the batteries are charged fully, a voltage difference that I can actually measure on my boat?

And with that, I'm done. The last word is all yours.

Neil, I'm trying not to be obtuse about this but I'm afraid I cannot give you the numercal answer you are asking for. This is what happens on my boat; after a night on the hook in the wilderness with a refrigerator running my batteries can be down to 50% especially if I watched TV etc, etc. When I start up the engine in the morning the alternator can be putting out 60 amps for a few minutes at say 13.9 or 14.0 volts. The batteries are really sucking it down. But the voltage throughout the system is wildly variable and only begins to stabilize slowly and in fact never becomes precisely uniform throughout. For the first few minutes I monitor the digital ammeter and voltmeter observing the rising voltage and falling amps readings on the meters respectively (both readings are at the main buss bar). The picture below probably was taken a few minutes after start up at maybe 800 rpms. But that voltage is way higher than what was being delivered to the resistor array. As the day progresses the voltage in the system slowly becomes more uniform, closer to alternator output voltage, though never achieves true equilibrium; but it can get close enough to "drill" a coil or something else at near alternator output voltage.

[sastanley]

SO, what I am thinking about doing is adding a few voltmeters to specific places..add one at coil (+) (behind resistor), and maybe at the ignition bus bar (in front of resistor), I have one at the 1-2 main switch posts (in the main panel) & one at the key.

That gives four distinct places to observe...this likely won't happen until next spring though..

I am still interested in this because the last time I had the boat out, (single-handed), the engine sputtered and died on me while the autopilot was holding the boat into the wind at low RPM and I was on deck dealing with sails after a 1+ hour motorsail. This was in an open creek with obstacles at a distance, but is unacceptable and I lose trust in the engine when this happens. So much so that on the return trip I purposely sailed in light winds to only run the motor for 10 minutes on either side of the trip.

[hanleyclifford]

Shawn - As an alternative you might consider using just one voltmeter and a rotary switch with sensing wires running to each location you wish to monitor. I used to do this with a Professional Mariner DFM - 4 that I still own. The only problem was that it only read to tenths of volts but had it's own selector switch built in. I'll get it out and post a pic later. I do have a Blue Sea digital voltmeter/ammeter - shunt included (no rotary switch) that I'll let go wicked cheap.

[67c&ccorv]

Careful guys...you don't know what you might create there!

https://www.youtube.com/embed/8H3dFh6GA

[hanleyclifford]

Here 'tis:

[romantic comedy]

maybe we can come up with a drill chart.

Have a voltage vs time plot for coil temp.
of course it is really amperage that we are following.

[hanleyclifford]

maybe we can come up with a drill chart.

Have a voltage vs time plot for coil temp.
of course it is really amperage that we are following.

That's what Neil wants. Whoever comes up with it gets to be platoon leader.

[sastanley]

Hanley, I was going to comment that even at Defender's prices, that Volt/ammeter from Blue Seas is wicked high dollars.

This is all just theory for me know...anything to keep me up at night and pre-occupied to avoid school work and other chores during the waking hours.

[smosher]

I used my standby battery and it was fully charged as I didn't use it all season.

I didn't use the boat as much this year due to various reasons, so the house batt didn't get charged as much. I did Charge it a couple of times but on the day to bring it to winter storage it was dead. I have a small digital meter that I wire across the battery terminals and it wasn't on. The battery is shot also. 2 years out of a walmart marine battery. My fault though on the battery. I plan on adding a solar panel for next year to keep the house batt charged.

I have the 55 amp Alternator and I have the sense wire connected to the common on the ab switch. A possibilty could be that my voltage at the coil is higher than 14.2. I used 14.2 as the basis for my calculations.

Actually I like rehashing the issue as it brought to light where my charging sense wire is connected to and maybe my assumption of the 14.2 is incorrect.

Steve

[hanleyclifford]

If you are sensing at the common on the battery switch that is just about the same as what I do at the main buss bar. You can expect that the alternator will be putting out as much as a half a volt more in order to satisfy the system. I recommend that you wire that voltmeter to coil+ (where the rubber meets the road, as it were).