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Twin engine battery charging on CC

Discussion in 'Electronics' started by zen, Apr 10, 2021.

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  1. zen

    zen Member

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    I'm purchasing a new CC for fishing with twin outboard engines. I learned today that only 1 engine alternator is charging the battery bank, which consists of 2 starter and 2 house batteries. They made a comment about making sure to run the stbd engine periodically to charge the batteries if I'm drift fishing or trolling on 1 engine.

    I thought it sounded strange so I looked up my previous CC which had 2 starter batteries and 1 house. On that boat, each engine's alternator charged it's own starter battery and the house battery was charged by either engine with an isolator wire. Is this an unusual/flawed setup? Any input appreciated.
  2. Pascal

    Pascal Senior Member

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    Each engine should charge its own battery then the house bank can be charged with a combiner. I would now accept a set up where only one engine can charge the batteries. What if that engine fails?
  3. NYCAP123

    NYCAP123 Senior Member

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    I assume both motors have alternators. Are they both working? My guess is that the owner spent his time running as opposed to trolling and found them overcharging. Since your plan is to troll just rewire it. But before buying have it checked to be sure they're wired that way for that reason and not because one alternator crapped out.
  4. Capt J

    Capt J Senior Member

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    Yes it's unusual. But maybe not. I know whaler on twin engine outboards. One engine charges it's bank, and the other engines battery bank is ALSO the house battery bank. But each motor had battery switches that could switch from bank 1 OR 2, OR both.
  5. NYCAP123

    NYCAP123 Senior Member

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    Exactly. The way he has it is most likely fine as long as he gets the revs up enough of the time and saves money. Option 2 would be to have each take care of their own battery, but that loses you an engine if a battery goes dead. Option 3 is the ideal situation to have both motors attached to all batterie and run through switches so that either motor can charge either or all batteries. It's also the most expensive.
  6. zen

    zen Member

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    For clarification this is a new boat. There might be an opportunity to get this changed before delivery. It's for Mercury V8 engines which I understand put out a ton of amps and that was cited as the reason.

    What exactly should I propose as my preferred setup? I've found a Balmar Centerfielder and a BEP Distribution Cluster with VSR, though BEP looks like it would need to replace the already installed battery switches.

    Also the setup on my previous boat with an isolator wire seems like the easiest way to do it. What am I missing here as to why they'd go choose this single engine route? I'm sure they'd pass along any cost and they know what they are doing, so I'm baffled as to why this is the default route.
  7. Fishtigua

    Fishtigua Senior Member

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    With modern 4-stroke outboards each engine MUST charge their own starter battery or they will not work properly. House batts really should be charged by each engine and then combined.

    Top quality starter batteries are worth spending extra on. We fit Odyssey, a bit pricey, but worth every penny.
  8. NYCAP123

    NYCAP123 Senior Member

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    Although you may be willing to pay for a better system the wrong price point could chase other potential buyers away. What they supply is adequate for the average buyer but someone who trolls a lot will want to upgrade.
  9. Pascal

    Pascal Senior Member

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    Problem is that most boat buyers don’t know anything about boat systems. This is why most brokers and salesman focus on drink holders, TVs and useless gizmos when showing a boat.

    this is also why most builders use aquarium grade bilge pumps which are near useless

    having each motor charging its own battery doesn’t cost anything.
  10. NYCAP123

    NYCAP123 Senior Member

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    You're right on target till you got to the last sentence. For the op the answer is simple. Ask the dealer what it'll cost to covert over to the better system. It won't be free but you sound like you'll find it worth it.
  11. Pascal

    Pascal Senior Member

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    The dealer shouldn’t have to fix the builders mistake... neither should the buyer. Each engine and gen should have its own battery. Anything else is a cheap shortcut.
  12. NYCAP123

    NYCAP123 Senior Member

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    It's not a mistake. It's an option. Each motor has it's own battery. It's just not set up for each motor to charge the batteries independently. It's more than adequate for the guy who cruises. Just questionable for the guy who spends his day trolling or the guy who wants redundancy.
  13. zen

    zen Member

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    I'm going to clarify the design tomorrow and offer to pay for individual isolators for each engine so they can charge their respective starter batteries and both the house. Does that seem like the simplest configuration?
  14. NYCAP123

    NYCAP123 Senior Member

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    I'd recommend adding battery switche that allow either motor to charge and use either or both batteries. That way a dead battery will never spoil your day or even slow you down.
  15. Pascal

    Pascal Senior Member

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    Not making much sense

    If each motor has its own battery how is it not set up for each motor to start and charge the battery it is connected to???

    the only question is how is the house bank charged. It seems only one motor charge the house bank which is just plain stupid in case that motor fails. It s not about trolling or cruising it a s about redundancy.
  16. Capt J

    Capt J Senior Member

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    Yes, and what brand of CC are we talking about here?
  17. NYCAP123

    NYCAP123 Senior Member

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    If one battery dies how do you start that motor short of using jumper cables? You ideally want charging and starting capabilities interchangeable and also to be able to connect the batteries in series. The house battery could be connected to either or both batteries.
  18. Pascal

    Pascal Senior Member

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    Every boat I ve been on has a parallel switch or solenoid... nothing new... been that way since the 60s
    Fishtigua likes this.
  19. NYCAP123

    NYCAP123 Senior Member

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    Didn't say it was new, but it's currently omitted on the OP's boat and in what you suggested.
  20. zen

    zen Member

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    Got some clarification on this today - either engine can charge the house battery if necessary, I just need to adjust the battery switch should I need port to do it. It's not automatic like previous boats but there was logic behind that decision that I agreed with after explanation and it should be fine for my needs. Thanks for the advice and commentary.