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  • #32384

    William Walter
    Participant
    Vessel Name: Positive rate
    Engines: Cummings 480ce
    Location: Long island
    Country: Usa

    I’ve lived with this since I bought the boat because it was low on the priority list and engines always started .port engine always starts fine and I usually start it first and turns over nicely. Stbd engine sometimes will not turn over as if the batteries are weak and relays start chattering.after that happens I checked batteries and have 12 .6 volts.ok so I know the answer is to clean every terminal in the 12 volt system which I have been working on.sometimes to start I hit crossover switch to get it going.since I’ve been cleaning the terminals it seems to always start but I’m not convinced I’ve licked the problem.today I checked voltage at batteries and then at starter.had 12 .9 at battery bank after shutting off charger for 5 minutes and 12 .6 at starter. Is this normal or should I be seeing 12 .9 at the starter in this situation.bill

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  • #32543

    William Walter
    Participant
    Vessel Name: Positive rate
    Engines: Cummings 480ce
    Location: Long island
    Country: Usa

    Thx

    Spent night on boat tonight and 12 volt system performed well but my indications were way off from anything I expected. I’ll work on problem myself and when I can get some sense out of this I’ll post again.Bill

    #32494

    Bob Waters
    Participant
    Vessel Name: TunaciousToo
    Engines: Yanmar 4lha-DTE
    Location: Dana Point
    Country: USA

    William,
    If you cannot find low voltage, you may have to disconnect each main wire at a time and check resistance. To check resistance, you need to disconnect the wires at the lugs. I would start with the main wire to the starter that is having issues. Those big lugs can come loose and it is hard to diagnose by testing only for voltage. In my situation, I also had a few bad main wires that were connecting 2 batteries in parallel. I replaced all the primary battery wires and lugs. They are not hard to make up. West Marine has a cheap lug tool or you can buy a better one at Harbor Freight. Blue Seas has a nice chart listing wire sizes for current load and wire run length. Remember the distance is to and from that battery to the load and back to the battery.
    Tony knows why your starter in not engaging. Just go one wire at a time.
    Bob

    #32492

    William Walter
    Participant
    Vessel Name: Positive rate
    Engines: Cummings 480ce
    Location: Long island
    Country: Usa

    12 volts

    Bob I seem to have good charging off charger .ive got at least 13.6 on both banks. I think by shutting off the engine bank switch and using the crossover button to start off house bank and having the same problem it tells me the problem is not in switch.interesting also is that volt meters on dash show about half a volt less than what I show on voltmeter when I put directly to batteries.i do need to get a digital gauge for engine bank so I don’t have to climb in bilge all the time with volt meter.i have three digital readings for house because both ecms get their power there and I added a light switch with a voltage readout.

    #32439

    Bob Waters
    Participant
    Vessel Name: TunaciousToo
    Engines: Yanmar 4lha-DTE
    Location: Dana Point
    Country: USA

    I had On/Off switches on my 26 Blackman to isolate the batteries. There was one for the start battery and another for the house bank. The start battery was never charging right. It always had 12.7 volt dc.
    I disconnected the all wires at the batteries to the switch to the starter and checked resistance. The problem was in the on/off switch- too much resistance. I replaced the switch and good to go. Maybe try this test of each component. The start battery had good voltage because it was connected to the on board charger. The starter was not getting the proper voltage because of the defective switch.

    #32408

    William Walter
    Participant
    Vessel Name: Positive rate
    Engines: Cummings 480ce
    Location: Long island
    Country: Usa

    12 volts

    Ok I have a picture of my 12 volt system.not the best but it’s what had on my phone.ill get better when I get to boat. When I purchased boat about 2 years ago the prior owner had all batteries tied together through a crossover switch so i suspected the batteries were weak and he was trying to get boat sold with batteries as is .when I purchased the boat I split the house and engine bank and operated that way .every once in a while starting was weak on stbd engine but I suspected weak batteries. Load tested and indeed some were weak so I bought 3 new group 31 batteries for the engine bank.thought I had problem solved but still every once in a while I go to start stbd engine and I get nothing or mag chatter.usually I just hit my crossover button and it starts. I did try shutting off the engine bank and used the crossover to start off the house bank and get chatter or a weak start also.so far I’ve done some terminal cleaning,new batteries and changed mag relay because I had a spare.engines always start on first turn so even though it may have low voltage at starter it usually catches.i do not have inverter option in schematic.thx Bill

    #32390

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

    One thing and one thing only causes that mag switch “chatter” .. You have a connection, but that connection or the wire going to it is experiencing a voltage drop to where the relay drops out and reconnects, drops out, over and over again. .

    I cannot tell you where to start, but if its been since new, then you just have to start upgrading all cable connections & size, switches etc etc., until all is right, and are “heavy duty enough to eliminate excessive or that much voltage drop.

    Do you have a DC POWER DISTRIBUTION DIAGRAM that you can post? Real help this way (over the internet), must start with that or we are all just “guessing”….Put your time in showing us on paper what you have–then, we’ll put in our time telling you the best way, (and cheapest way) to sort it out..

    Tony

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