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  1. #11
    Join Date
    Mar 2004

    Default Re: How is my alternator connected to my 2 batteries

    Quote Originally Posted by RichardS View Post
    Simon, it's worth saying that running an alternator which is not connected to the battery will not cause any harm as the field coils will not be magnetised and no current will be generated. I've run altenators on the bench many times to test bearings etc and it does no harm. Suddenly disconnecting the alternator whilst it is running and generating is not advisable. It all depends upon what your switches actually do if you change them whilst the engine is running.

    Tnx, yes previous owner knew even less about the boat.


  2. #12
    Join Date
    Dec 2007
    S.W. France

    Default Re: How is my alternator connected to my 2 batteries

    Wired up the Trapper, which has a 1/2/Both main switch to select which battery is in use. But, the charge lead from the alternator goes through the diode splitter direct to the batteries, so they both charge when the engine is running. The breaker board is fed from the 'domestic' battery. But selecting 'both' would link the engine start battery to it. Normal use is to select 1 to start the engine. With the option of 2 if 1 fails. ( I think that makes sense..)

  3. #13
    Join Date
    Apr 2017

    Default Re: How is my alternator connected to my 2 batteries

    This is how mine is wired , I have an intelligent battery manager.(smartpass made by CTek).
    -Alternator is connected and charges the Start battery first, when the start battery is full the smartpass opens a gate and charges the House battery .
    -Shore power and solar panels are connected and charge the House battery first, when that in turn is full it opens a gate the other way and keeps the start battery afloat.
    - the smartpass ensures that all power consumption is from the House battery at all times , except if the alternator is charging when the engine is running then it directs the extra juice from the alternator to the consummers , meaning that the start battery exclusively reserved for starting the engine alone.
    - the Smartpass has an outlet for non essential consumers such as the fridge , entertainment system etc, this cuts these off automatically first, to the advantage of the priority consumers like vhf, gps, AIS if my house batterygets low.

    As an overide , I have a manual Main battery selector switch which I can use to manually select my House battery (or both)to crank the engine in the event that the start battery suddenly gives up the ghost.

    I am extremely satisfied with the Smartpass intelligent multiple battery manger from Ctek. It has a series or led indicators telling me which battery is being used and what direction any charging is going.
    Last edited by benchmark; 20-11-17 at 20:53.
    Ocqueteau 8.15,200hpNanni.
    Buster Sun R,25 hp outboard

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