Ignition snafu

[Scott T-Bird]

I have a newer Yanmar control panel that has just 4 buttons. There is no key for ignition. The buttons from top to bottom are: Engine Start, Engine Off, Glow Plugs, Ignition On/Off. When I started up on Saturday morning I muffed the sequence by not opening the raw water intake. As soon as I realized it, I quickly hit the wrong button. I hit the Ignition On/Off button, which apparently disabled the engine shut off button. When I realized my mistake and hit the engine shut-off, nothing happened and the engine continued to run only it was sucking air. It startled me into immediate action and I managed to open the valve quickly enough to allow water to flow without any damage to the impeller. This all happened in a matter of seconds. After I had a chance to think about it, I wondered if I damaged a diode. I shut down and then started again, so I figured I had no problems.

Later in the day, under somewhat stressful conditions at the entrance to Double Creek Channel, I attempted to start the engine. I got a single click and then nothing. The engine panel wouldn't even light up again. I looked at the battery monitor and found both the house bank and the start battery to be fully charged. I was puzzled so I started the engine with the house bank. That was yesterday afternoon. That was when I was really concerned that I damaged a diode, but I don't know how those things work, so I don't really know how to go about testing for that condition. I use a Dual Circuit Plus switch.

In any event, this morning, I started the engine with the start batt without any difficulty so I'm back to wondering if I have a problem or not. As I'm writing this, I suddenly just realized that I already noticed a week ago that the negative cable on the start battery is badly corroded. I tried to clean it up then, but I didn't have the right tools. Then I promptly forgot about it.

Next week, I'll replace the cable … but I still wonder if I damaged a diode? (Are there diodes in the switch?)

 

[BarryL]

Hey,
You have a few choices:
-Does your boat have a voltmeter or ammeter anywhere? If so, when the engine is running the voltage should be over 13V and / or you should see positive amps going into the battery. That means your alternator is generating electricity and the batteries are being charged.
-If you don't have voltmeter, do you have a cigarette lighter socket? If so, then buy a cheap plug in meter like this one:
https://www.walmart.com/ip/TSV-4in1...9951&wl11=online&wl12=303598922&wl13=&veh=sem
You last (and best) option is to buy buy and learn how to use a multimeter.
Good luck,
Barry

 

[jssailem]

Scott.. A diode is like a one way path for electricity to flow. It will not flow in the other direction.

Since you were able to start and stop the motor after the errant button push I suspect you are ok.
Not sure why there would be a diode in your system. Do you have a chart of the circuit? Does it say there is a diode?

If something doesn’t work then you need to break out the meter and go looking for the problem.

 

[Mark Maulden]

Does your engine manual have a schematic of the panel? Or can u get it online? That would answer your question. I doubt you harmed anything. If you did, then the panel design is wrong..you should be able to hit any button at any time and not damage anything...Except if you hit start while the engine is running..Not a good design locating start right next to stop....fix the battery cable

 

[Davidasailor26]

I think you're probably fine. As I understand it the diodes at risk are the ones in the alternator, from charge current to the batteries suddenly having nowhere to go. If the alternator is still putting out adequate voltage you should be ok. The problem starting was probably just from the corroded cable.

 

[capta]

Corrosion of the terminals for the negative ground wire to the engine block from the batteries is the most common cause of 'mysterious' electrical problems on a boat.
Unless you have actually inspected the sea water impeller, I would consider it likely that you have indeed damaged it. Just because you have sufficient water flow out the exhaust does not mean the impeller is OK or that a blade or two hasn't ripped off and moved downstream to block a water passage in the engine or heat exchanger.

 

[dlochner]

Some Yanmar panels have a known problem with an undersized wire supplying current to the solenoid. This slight drop in the current is sufficient to prevent the solenoid from fully engaging the starter. The fix is to replace the wire with a heavier gauge wire.

The symptom is intermittent starting. Hit the start button, the solenoid clicks and then nothing hit it again and it starts.

The problem you have is likely one of two possibilities, the poor Yanmar wiring or the cruddy battery connection. Either one will cause the kind of symptom you experienced. That it happened after your botched start, is simply coincidence.

 

[Scott T-Bird]

The problem you have is likely one of two possibilities, the poor Yanmar wiring or the cruddy battery connection. Either one will cause the kind of symptom you experienced. That it happened after your botched start, is simply coincidence.

Thanks for all replies! I think it was coincidence. It's funny, I completely forgot about the cable until I almost finished writing the post. I was focused on diodes, since they are a bit of a mystery to me. I think I wouldn't recognize a diode if I saw one. We were bouncing around quite a bit entering the channel with all the power boats creating a washing machine effect. The only diodes I'm aware of are associated with the alternator and I can check the current output with my monitor. I'll also look at my impeller. I put a new one in last year but I've had a lot of issues with blocked intake flow during the past few seasons. It won't be a bad idea to change it out regardless. It is very easy access on my boat.

 

[Cowpokee]

I was focused on diodes, since they are a bit of a mystery to me. I think I wouldn't recognize a diode if I saw one.

Diodes can be explained simply as a check valve for electrons; they only let current flow in one direction.
I can also simply explain how this takes place insde the device if you are that interested.

 

[Scott T-Bird]

Diodes can be explained simply as a check valve for electrons; they only let current flow in one direction.

That part of it is easy enough to understand. I guess the mystery to me is, where are they needed? What components will have them? Practically speaking, what causes them to be damaged on a boat? I've heard that you can damage diodes if your switch doesn't "make then break" its electric connections when you use the battery switch to change banks while loads are active - does this damage the alternator diodes? A situation with alternator diodes (I'm reading there are 6 in a rectifier assembly that converts AC to DC current) being damaged when there is no destination for the current makes sense to me, but I wouldn't know where to find the diodes or recognize them. There are some interesting youtube video's that would help!

Never having any reason to think about diodes, I guess I haven't paid any attention to their function. I think I've also heard that you shouldn't turn the ignition off before shutting engine down, for concern over diodes. Hence, my question! I was very surprised that the engine shut-off button was disabled by hitting the ignition button first. Perhaps that is a feature to protect diodes. On my old panel, with a key switch for ignition, I could turn ignition off and then shut engine down, not that it was recommended. That was with a shut off that had a cable that manually was pulled to starve the engine. Now it is electronic.

 

[Scott T-Bird]

Some Yanmar panels have a known problem with an undersized wire supplying current to the solenoid. This slight drop in the current is sufficient to prevent the solenoid from fully engaging the starter. The fix is to replace the wire with a heavier gauge wire.

I'd be interested to learn more about this. What would be considered an undersized wire and what vintage would that be? Mine is relatively new, having installed a new panel and engine in 2013.

 

[dlochner]

The wire on my Yanmar panel was 14 or 16 gauge. It was replaced wire a 10 gauge. No problems since then. There are several ways to skin this cat. Out cruising now typing a phone. Remind me next week. And I’ll send a liger more detailed explanation.

 

[Mark Maulden]

Scott, what diodes are you concerned about? There are diodes in the alternator and there are probably diodes in the panel for alarm functions. Evidently, when you switch ign off, it removes power to the panel. Then no power available at the stop switch to go down to the solenoid on the engine that cuts off fuel. Looks like that ign button needs a guard. My brand new Beta keyless panel has no “ign” function. If I want to wake things up, I just momentarily hit any button.

 

[Scott T-Bird]

Scott, what diodes are you concerned about? There are diodes in the alternator and there are probably diodes in the panel for alarm functions. Evidently, when you switch ign off, it removes power to the panel. Then no power available at the stop switch to go down to the solenoid on the engine that cuts off fuel. Looks like that ign button needs a guard. My brand new Beta keyless panel has no “ign” function. If I want to wake things up, I just momentarily hit any button.

Interesting about no Ign button. I don't think I have any concern for diodes at this point. I'm pretty convinced right now that the corroded battery cable was the issue. It just happened to be coincidence. I don't think the Ign button needs a guard. I've never done this in the previous 4 years till now, and now even less likely to repeat the mistake. I think it is probably a reasoned function so I see no reason to change it.

They certainly aren't clearly labeled though! I can think of a few occasions when I thought the battery was dead when I pushed the engine off button, expecting to start the engine!

 

[jlp0217]

Running the motor for a few minutes with the cooling valve closed will not destroy an impellor. Running an impellor dry, i.e. with no water in the pump, for more than a few seconds will.
Running the engine with no battery connected to the alternator will destroy the diodes in the alternator in a fraction of a second, but the ignition switch off should not isolate the alternators from the battery.
There could also be a diode based battery isolator, but if so it should be pretty bullet proof.
If it were me, I'd rewire the kill switch to get its power from before the ignition switch rather than after.

 

[Maine Sail]

Scott,

Killing the ignition will not blow the alternator diodes. Disconnecting alternator B+/Output from the battery, when the alt is operational, is what can blow the alternator diodes. It can also ruin or damage sensitive electronics on-board the boat due to the resulting voltage transient. In other words don't rotate the battery switch through OFF with the motor running unless the alt B+ is directly wired to the bank.

I've done six blown diode repairs this season. Five due to the battery switch being flipped though OFF with the motor running and one because the 40 year old break-before-make battery switch was moved from 1 to B when the motor was running...

 

[capta]

That part of it is easy enough to understand. I guess the mystery to me is, where are they needed? What components will have them?

Alternators produce AC electricity. The diodes turn that AC into DC. Its as simple as that.

 

[Stu Jackson]

I think I've also heard that you shouldn't turn the ignition off before shutting engine down, for concern over diodes

Which just proves that you can't believe everything "...you've also heard..." somewhere. None of was born electricians. We applied ourselves and learned. Google the 12 V Alternator Handbook and download and read it. If you can't find it, pm me and I'll send you a copy.

The ignition is connected to the regulator which tells the alternator to produce power. It essentially turns the alternator on. It is separate from the AO (alternator output) which Maine Sail calls the B+ of the alternator. If you interrupt the AO when the alternator is running, in any way, you can blow the diodes on the alternator, making it a useless hunk of metal. You can remove it and take it to an automotive repair shop and they will fix it for much less than the cost of a new alternator. Everyone should know a good alternator shop near them. Get to know them, like really good friends. One of the first things I did when I moved here.

 

[Scott T-Bird]

You can remove it and take it to an automotive repair shop and they will fix it for much less than the cost of a new alternator. Everyone should know a good alternator shop near them. Get to know them, like really good friends. One of the first things I did when I moved here.

I can give it to my step son. He is getting really good at electronics & automotive components! He loves that stuff.

 

[Ward H]

I thought the battery was dead when I pushed the engine off button, expecting to start the engine!

BT,DT,GTTS.