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  • #25761

    David Carter
    Participant
    Vessel Name: TenaSeahorse
    Engines: 6cta8.3
    Location: Knoxville
    Country: USA

    I have twin Cummins 450s 6cta 8.3 on a large boat. My batteries where bubbling out of the vents. 8d x 7. I have an inverter bank of two, house bank of two, one for each engine and one for my thruster. To start my alternator was swinging every few seconds from 14.7v to 12.7v I changed all my batteries and disconnected the heater for that engine. The swim stopped now it’s just charging. The batteries should be charged my inverter ran all night before I tried it I ran for about 10 minutes it continuously charged at 14.7v. It was isolated to only charge one 8d. I started the other engine it stayed at 12.7. My engines start immediately.
    I’m not sure where to go from here. Would an alternator go bad an continuously charge. Is the rectifier inside the alternator. Is it as simple as checking diodes an changing them.
    Thank you ahead of time. I spoke with Corey and he help me to get heater disconnected.

Viewing 5 replies - 1 through 5 (of 5 total)
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  • #25857

    David Carter
    Participant
    Vessel Name: TenaSeahorse
    Engines: 6cta8.3
    Location: Knoxville
    Country: USA

    Thanks again

    I really appreciate that I can post these questions and to have someone of your caliber to answer.
    Under Tony’s tips in the electrical section you have typical dc distribution.
    I have a manual switch on the combiner and I disconnected it. When I check voltage with the engine running there’s only one battery being charged. I’m getting the leads labeled. I ran each engine and checked the voltage on the batteries. The engine batteries are stand alone unless that combiner is engaged. I also ran the inverter and the other three phase charger separately to label what is charging what.
    I’m trying to figure out the items on the engine. The ones I posted pictures of. They look like relays. I see one is the aux. mag switch I see it on the starter crank fuel solenoid schematic but not really sure what it’s for. Also what is the alt. Diode do It’s next to the 10amp reset button in my pictures. I see its changeable I’m wondering if it could cause my problem.
    It may be a couple of days before I can spend much time tracing the system. I’m going to try to sneak over and take pictures of the whole engine room. I want to do any maintenance I can to prevent any future problems. I need o rings and lube for the the aftercoolers. Maybe belts and hoses. I’ll Start another thread for that. I don’t have much on my specific boat and systems Hi-Star 47 I’ve looked on the net but nothing out there.
    So again thank you so much I will purchase as much as I can from your company.

    #25853

    Tony Athens
    Moderator
    Vessel Name: Local Banks
    Engines: QSB 6.7 550 HP
    Location: Oxnard, CA
    Country: USA

    What diagram of mine were you looking at? I typically stay away from combiners as they make it close to impossible to troubleshoot charging issues….

    Post the diagram you looked at..

    Do you have a diagram for what your have?? Your pics are good for now, but figuring out what is going on won’t happen with what you have post so far.

    Basically, it’s going to come down to this without a diagram at least initially.. You’ll have to do a temporary rewire eliminating the combiner and hooking up each alternator output to ONE battery and then go from there–system by system.. In so many words, you are going to 100% isolate engine from each other and from the boat systems to do this… Plus, you are going to need DVM’s for each battery bank to “see” battery terminal voltage at all times.. The DVM’s must be fed direct form the battery terminals, both + & –

    Rob S. has postings on this…………….Do a search.

    The air heater thing is easy–Leave the fuses out on both engines until you get the rest fixed. IMO, I’d toss them. They create way more issues that they solve

    Tony..

    #25822

    David Carter
    Participant
    Vessel Name: TenaSeahorse
    Engines: 6cta8.3
    Location: Knoxville
    Country: USA

    Tracing my dc

    I just looked at your typical dc circuit for twin engines. I got the idea if that’s the diagram your looking for I think mine is close to that. I had a house bank of two 8ds and a separate inverter bank of two 8ds. I was running out of inverter power in less then 8 hrs so I connected the house and inverter banks. Most of my stuff was running off the inverter and only a few lights off the house. I will try to trace my system But that’s four batteries and I have one for each engine with another in the bow for my thruster. Also a 27 for the gen.

    #25812

    David Carter
    Participant
    Vessel Name: TenaSeahorse
    Engines: 6cta8.3
    Location: Knoxville
    Country: USA

    Thank you

    I spent the yesterday tracing my batteries as far as what charger is charging what. I have an inverter that charges and also a phase three smart charger. Not to mention the 22sl alternators. I turned both charger off and still had the 14.7 output from the alternator. The alternator 22sl has a negative and what I believe to be a two prong plug for an internal regulator. There is only one wire coming out of this connection it goes into a connection that has a red an black leaving and going into a harness that raps around engine with many splits and relays I’m guessing. Each engine has a single 8d that is either isolated or switched to parallel. The hot from the alternator goes to the starter and that sprouts other hots Anyway I will do what it takes to track down the problem. I’m not sure the best way to proceed. Must I strip the harness and track each wire thru out. Or maybe add a jumper to my ohmmeter and try to find the other end of each lead. What a mess. Would there be a way to check the internal rectifier like maybe I should take the one wire coming out of the two prong connection on alternator and run it to batteries or just disconnect and look for a response. Looking on YouTube I see someone had a similar problem and hook up an external rectifier. There’s not much about an alternator that continues to charge most are about under charging. It’s puzzling that with the heater hook up the output swung 12 to 14.7 and with fuse out of heater it’s constantly 14.7. Seems like the rectifier was switching with the heater. I was thinking of switching alternators but I don’t want to fry the other one. But stripping the harness to trace the wires is going to be a mess. So if there’s any easier checks I could do before tearing things up I’m in. Please I’m not complaining and will follow your guide. I have more projects to do this winter. Like cleaning after coolers and anything that should be done after a thousand hrs.

    #25763

    Tony Athens
    Moderator
    Vessel Name: Local Banks
    Engines: QSB 6.7 550 HP
    Location: Oxnard, CA
    Country: USA

    David,

    #1 will be this, if you really want help———– You, or your designee, has to get passionately involved, and I mean really involved in the DC POWER ELECTRICAL POWER DISTRIBUTION SYSTEM on your boat..

    #2–I will 100% put in the time to sort you out, if and only if you do #1, and you follow my lead 100%..

    #3– Initially, that will be to supply simple sketch of your current DC power distribution system that encompasses all “8D x 7” and how all is interconnected ..

    Think about it———You put in the time and I’ll put in the time –During this you’ll learn how your boat is wired currently, and then I’ll put in the time ( for free) to sort it all out..

    Seems like a fair deal to me?

    Tony

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