Suddenly Shutting off both engines DDEC III 16V92

[White Hatt]

Hello, I have a Hatt 65 1997 with DD 16V92 DDEC III. I was cruising at 1700 rpm and everything regarding the engines was ok (temp, pressure, volt, etc.). Suddenly the engines shut off at the same time, no power on both engines displays. I went to the engine room and everything was ok, then I turned off and then ON the master switch of each engine, wait a few minutes and the power came back to the engines DDEC displays. So I turned on the engines and started cruising again at iddle speed. After 5 minutes both engines shut off at the same time again. After that, I did the same thing....went to the engine room, check everything and turn OFF and ON both master switch, wait a few minutes and the power came back to the DDEC displays on the bridge. So I started the engines and continue cruising the boat. That happened 20 times or so, every 4 or 5 minutes, Even when I was docking the boat. Never came out an alarm or a code that gave me an idea what was happening. SOMETHING was cutting the power supply at both engines.The next day, I turn on the engines and leave them 2 hours on and nothing happen.Anyone has an idea what it's going on here? Hatteras has some sensor that cut the power supply to the engines? Or it is something regarding the DDEC?

 

[Pascal]

One possibility should be a malfunction with the fire monitoring system, it's probably the only thing that could shut down both engines but I think that it would shut down the engines while keeping the displays on although I m not familiar with the DDEC set up. Also, the fire system would have turned off th generator.

You need to see what both engines have in common. You have two battery switches so they can't both be the problem but how about start bank? Do you have separate banks? If not, it could be a loose connection at the batteries.

If it happens again, before resetting the batt switches, I'd poke around with a voltmeter to see if you have power at the batt switch terminals, at th engines, etc...

 

[saltshaker]

I'm no DDEC expert but could be a voltage issue. They are very sensitive to fluctuations in voltage but very odd they both shut down at the exact same time. Both systems should be separate. Only common link I can think of would be in the throttles as the 2 systems are connected to sync the engines.

 

[White Hatt]

Yes I have separate banks batteries but all of them are conected to a battery isolator.The strange thing was that the day after, the engines started like nothing happened the day before.I checked the fire alarm and cut one cable of that sensor that it is inside the engine room and it did not cut the DC power supply of the ddec's display. There is a Halon alarm but I really don't know how it works...I know that alarm will shut off the engines (and should shut off also the generator as Pascal mentioned) but I am not sure if that Halon system cut the DC power supply or close the inlet air to the engines. If there is a voltage issue, what I should check? The batteries are ok and also the connections. I do not know much about the DDEC's, that's why I do not know if It may be a problem with any sensor of the boat or if it may be a problem with the DDEC's or the engine room interface module or anything else. I really appreciate your help and your time. Thanks

 

[Pascal]

The halon system, assuming it's a fireboy, will not kill DC to the engines, it will just shut them down, along with generators and blowers, using the shut down solenoid or whatever the equipment uses. You should have a box somewhere with a number of wires connected to it. There will usually also be a round indicator gauge showing the system status with an override switch which will let you start the engines after a shut down. I don't think this is your problem but you need to know how this works in case your system accidentally discharge or fails.

I don't see any sensor or system which would shut down the engines and also cut power. It has to be a electrical issue. Intermittent electrical issues can be very hard to troubleshoot. With separate battery banks I just don't see anything that would cause both engines to shut down and loose all DC power Since thinly common link is the isolator, I'd suspect an issue there but I just don't see how that would drop voltage randomly causing a shut down

That said, a few years back I had a massive electrical failure on a boat with twin cats (electronic 3412Es) , twin gensets, all powered by their own independent battery banks. Woke up one morning with no DC power whatsoever on the separate house bank due to a failed 24v battery charger. What became a complete and unexplained to date mystery is that the generators (powered by separate 12v batteries charged by a 12v charger) would not stay running once the start switch was released. The cats would start but would not stay running either once the key was released. After half an hour of piling around the problem cured itself, no idea why... And I was able to fire the mains so the alternators would charge the house bank. I suspected the charger failure somehow affected the isolators which allowed the two alternators to charge the three 24v banks (port stbd and house) I never understood the problem and it never happened again...

So, in your case I d keep an close eye on voltages including the charger, but also engin voltages while running

 

[saltshaker]

Do you run with the charger on? next time this happens, try shutting down the charger or putting the charger on and in manual mode. If you get a mechanic involved, make sure he is an expert with DDEC not just a Detroit guy.

 

[White Hatt]

I don't think my halon system is a fireboy. But if this is not the problem, all I can think of is that is a voltage problem, wether in the DDEC system or in the DC power supply. It is like you said, a big mistery find what can cause this random issue.Regarding the battery charger.. yes I was cruising with the battery charger on.Thanks for your opinion. Regards.

 

[Pascal]

I would do some research on the fire system as it looks like you have three boxes. The labels indicate one box controls both main engine shutdown and the other two control the blowers and genset Maybe that one box is sending the shutdown order but no idea why it would shut all D.C. To the engines. Maybe someone familiar with that system can chime in

 

[White Hatt]

Thanks a lot for your time... I am also trying to find out something else about this fire system.

 

[SKYCHENEY]

Bad ground? Malfunctioning Vanner box?

 

[JLR]

Sky - it could be a bad Vanner but I have one for each engine. I suspect the OP probably does as well.

 

[kelpy]

It has to be an electrical system that both engines have in common. I lean toward a bad Fireboy control box. Get your fire system guy down and have him bypass the control box for testing.

 

[White Hatt]

I think I have only one vanner box from 24volts to 12 volts for the elctronics on the bridge. All of the three battery banks are 24 volts.I checked the ground and verything seems to be ok.

 

[tonytrakovich]

I thought I read that the ddec ecru can run from 12-32vdc. Since both engines shut off at the same time it has to be something that interrupts power to both engines. Fire system definitely comes to mind as mentioned by other very knowledgeable posters. i don't know anything about ddec but, what normally stops those engines? Is it a shut down solinoid like my 12V92's? Or does it shut off fuel injectors? If the fire system shuts them down, wouldn't you have to hit the reset button on the boxes to restart?I would look at what supplies power to both engines. My boat has ignition fuses in the ER Batt panel. Do all the gauges die when the engine quits?

 

[White Hatt]

Yes both of the DDEC's displays engines on the bridge died at the moment the engines shut off....No power on those displays.

 

[Tim Powell]

Gotta ask a question here. As i understand only fuel and air shut down a engine. That being said something has to shut fuel or air off. Mine the manual shut down cuts off air and the stop button shuts off fuel. (I think) When the DDEC it shut down (stop Button) does it shut fuel off ? Is it possible to back track to see what the shut off is tied to. If both are shutting down then One item has to be controlling both like every one else the fire box seems the grimland.
I AM STUPID TO DDEC BUT I WOULD LIKE TO LEARN HERE.

 

[kelpy]

Somewhere in your engine room you will find this. Check that all connectors are clean and tight.

 

[White Hatt]

Yes, It is in the engine room. Do you think it can be a bad connection?

 

[kelpy]

It could be. It is one of few things that would cause both engines to turn off at the same time. Pull the power connection and let it sit for 30 minutes or so and then plug it back in. Check that all of the twist connections are tight. Has any water or salt spray got to it?

 

[White Hatt]

This is the ERIM that I have inside the engine room.