Click for United Click for Burger Click for Dockmate Click for JetForums Click for Abeking

Advise Needed for Bertram 12v Rewiring

Discussion in 'Bertram Yacht' started by etang789, May 20, 2020.

You need to be registered and signed in to view this content.
  1. etang789

    etang789 New Member

    Joined:
    Jul 5, 2017
    Messages:
    29
    Location:
    Hong Kong
    I have a 1987 Bertram 42 will be starting the repowering work soon at the shipyard. I thought of changing to 24v but since the boat came with 12v from factory seems like many little things needed to be changed.Need some advise suggestions in how to rewire the 12v system? We have very hot climate here so the genset will run whenever we using the boat to blast the AC.

    It is going to have:
    2x Cummins
    1x 16k Genset
    2x Solar Panel ( No Shore Power Available )

    BEP Battery Management Panel with Twin Engines seems like a good place to start
    Not sure how to tie in the Solar Panel with Charger into the system
    Need to find a suitable battery charger

    Some 12v template from Bluesea I found:
    [​IMG]

    [​IMG]
  2. DOCKMASTER

    DOCKMASTER Senior Member

    Joined:
    Feb 26, 2012
    Messages:
    414
    Location:
    Ketchikan, Alaska
    What are you trying to solve or gain by going to 24V aside from the efficiency increase you get? Have you put together a list of all the 12v things you have that will not accept 24V?

    16K seems like an awfully big gen for a 42. Even to blast A/C. Have you done a power load analysis?
  3. Pascal

    Pascal Senior Member

    Joined:
    Feb 29, 2008
    Messages:
    4,988
    Location:
    Miami, FL
    I like to have isolated systems with each engine and generator having its own battery, along with the house. The only connection I want is a manual parallel switch between the engine banks.

    I repowered and rewired my 32v 53 Hatteras MY two years ago. Cummins charged over $1000 extra for 24v factory recon C series so I went with 12V. Each engine has its own 8D start battery and my 18kW generator has its own G31. All charged from a Pro Marine with 3 outputs.

    The house side is 24v with a pair of 8Ds and its own Pro Mariner Charger.

    at some point I will add a 24 alternator to charge the house batteries in case of a genset failure but at this point since we re only use the boat locally it s not a priority. If we loose the genset it s game over and go home anyway.
  4. etang789

    etang789 New Member

    Joined:
    Jul 5, 2017
    Messages:
    29
    Location:
    Hong Kong
    My Bertram always had 12v. The system is too old without proper isolation that’s why I’m redoing it.

    Actually I don’t think I will gain much aside from efficiency, maybe 24v will have less choice of related product.

    I’m getting an amazing deal with the 16k genset that’s why.
    Last edited: May 21, 2020
  5. DOCKMASTER

    DOCKMASTER Senior Member

    Joined:
    Feb 26, 2012
    Messages:
    414
    Location:
    Ketchikan, Alaska
    You can add isolation without going to 24v. Or you can put in two systems, 12v and 24v.

    The generator will not be a good deal if you are running it underloaded all the time. You said you will run it whenever the boat is in use. I think you will be severely underloading it and will lead to continual issues with your gen. Strongly suggest you size the appropriate gen.
  6. Pascal

    Pascal Senior Member

    Joined:
    Feb 29, 2008
    Messages:
    4,988
    Location:
    Miami, FL
    Better slightly oversized than always running close to the limit. The heavier the load the more heat, some margin is nice to have.

    I have an 18kW on my 53 which typically runs at 60% load. Almost 20 years old and 3000 hours. No issues.
  7. DOCKMASTER

    DOCKMASTER Senior Member

    Joined:
    Feb 26, 2012
    Messages:
    414
    Location:
    Ketchikan, Alaska
    I agree on slightly oversized but 16kw on a 42? What does the boat have now that meets the demand 9kw? Maybe 12kw? What else has to be modified to upsize to 16 kw? Maybe it's worth it. Just hope the OP has done homework other than just going to 16kw because the gen seems like a good deal.
  8. etang789

    etang789 New Member

    Joined:
    Jul 5, 2017
    Messages:
    29
    Location:
    Hong Kong
    yea too bad the ProMariner products don’t support 220v
  9. etang789

    etang789 New Member

    Joined:
    Jul 5, 2017
    Messages:
    29
    Location:
    Hong Kong
    so almost like this panel setup. But Not sure how to tie in the solar panel charging.

    Attached Files:

  10. Pascal

    Pascal Senior Member

    Joined:
    Feb 29, 2008
    Messages:
    4,988
    Location:
    Miami, FL
    Can’t quite see the labels on the low res image but probably

    I guess it depends on the boat layout but I am done a big fan of having a central battery switch panel. Yes it is neater but in most case it drastically increase the cable runs between batteries and engines. I also like having the battery switch either accessible from outside the machinery space or at least right inside the door to allow an easy shutdown in case of an electrical fire.
  11. DOCKMASTER

    DOCKMASTER Senior Member

    Joined:
    Feb 26, 2012
    Messages:
    414
    Location:
    Ketchikan, Alaska
    Your solar panels would be stand alone. You run them through a charge controller connected directly to your battery bank with appropriate breaker protection of course.