Fuse size.....

Discussion in 'Boating' started by harper81, Mar 1, 2009.

  1. harper81

    harper81 Member

    Messages:
    340
    State:
    Summerville, SC
    I need to extend my power wires for my motor to reach my battery's new location and I figured since I am doing this I might as well add an inline fuse. Anyone of how many amps a 15 hp Johnson pulls to crank the engine? The fuse holder I have has a 60 amp installed, but this is a car stereo wiring kit i have and that seems a bit large.
     
  2. trnsmsn

    trnsmsn New Member

    Messages:
    1,214
    State:
    Missouri Originally Now I
    Good morning, if you have access to an inductive amp meter, or know someone that does, you can measure the amperage draw & install a fuse with a slightly higher rating. It will have to be higher due to the fact that as your voltage supply (low Battery) decreases the amperage will increase.

    For instance,If your dryer in your house draws 30 amps @ 220 volts, it will draw 60 amps @ 120 volts. So if your 12 volt battery becomes low on charge, you'll still want to be able to crank the engine w/o blowing the fuse. A dead short will blow the fuse immediately any way.

    HTH, Elliot
     

  3. screamnreels

    screamnreels Member

    Messages:
    599
    State:
    Halifax county
    Any fusable link Is great.I would size the fuse for the wire size.Just keep the same or larger size wire to compensate for the extra length.All you want to do is keep it from a dead short,where most any fuse will blow.
    Chris
    Also use marine cable it has a better insulation and is tinned.
     
  4. Katmandeux

    Katmandeux New Member

    Messages:
    1,618
    State:
    Checotah, Oklahoma
    Why are you doing this? If it were needed, it would already have one.

    Nobody, that I'm aware of, puts fuses in starting circuits. There's a reason.
     
  5. trnsmsn

    trnsmsn New Member

    Messages:
    1,214
    State:
    Missouri Originally Now I

    NOT so true anymore, several vehicles, mostly imports use fuses in the starting circuits. They are usually in the 80 amp Range. They are basically a Buss bar, in a smaller package.

    HTH, Elliot
     
  6. harper81

    harper81 Member

    Messages:
    340
    State:
    Summerville, SC
    I didn't do it so no worries. I had the wires going down the middle and that's why I was worried. No protection for the battery if the wires were nicked. But I ran them around the side of the boat so no worries about damaging them anymore.

    And just out of curiosity what is the reason nobody fuses starting circuits? You stated there is a reason, yet you failed to give the reason.

    I went with the car audio wire because I all ready had it on hand. Its weather resistant and the insulation is thick. This wire didn't come out of a cheap kit from Walmart, I paid a pretty penny for it when I got it. And it was 8 ga. which is actually bigger than the motor had. the motor had 10 ga.
     
  7. Katmandeux

    Katmandeux New Member

    Messages:
    1,618
    State:
    Checotah, Oklahoma
    LOL! I don't know, that's why.:smile2:

    My guess is that the initial current surge is so high that it would require a fuse so big that it would afford little or no protection. Maybe a sloblo would work...I dunno. Maybe Elliot can fill us in.