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Thread: Battery and Charging Configurations

  1. #1

    Default Battery and Charging Configurations

    I had a 28' Bayliner that needs to have the power and charging systems reconfigured. The twin engines used to have the built-in stators which I have pulled and plan to replace with two marine alternators. I have two deep cycle "house" batteries and one "starter" battery, as well as two Perko master battery switches. I also have an onboard battery charger used when the boat is on AC power.

    My initial plans were to connect the house batteries to the "1" input of each of the Perko switches, and the starter battery to the "2" input of each of the switches: Perko switch "A" would connect to a +12VDC bus while switch "B" connects to the starter motor of each engine.

    I'm looking for suggestions.

    Does these seem like a correct setup?
    Will each alternator connect directly to each battery bank?
    Is an automatic charging relay required for the battery charger between the battery banks?

    I've loked all over the Internet for an applicable schematic but couldn't find any with the configuration: 2 battery banks, 2 alternators, 1 battery charger, etc.

    Any help would be appreciated.

  2. #2
    Member Soundfisher's Avatar
    Join Date
    May 2006


    Look up Twin Battery Schematics in the boating subforum/mod section. Spoiled One has an excellent link to follow that will help you.Good luck

  3. #3
    Join Date
    Apr 2006


    Your sw and battery layout look good.

    Depending on what ac charger you have you could use a battery isolation diodes instead of an relay.

    Are you going to run #1 engine alternator to house batteries and #2 engine alternator to starter battery?

    One possible problem is if you have one of the Perko sw on both you could drain all batteries.

    Personal I don’t like battery in parallel, but if done right there no problem.

    You remove the engine “stators”. What type of engine do you have?

  4. #4


    Thanks, guys. I appreciate the help. I've actually posted this question on several other forums and thn I came across this site ... glad I did. Between the boating, hunting, and PWS posts I've been given a lot of great information. My questions on the power setup have seemed a bit voodoo, however ... no one besides you guys have responded (or I'm just an idiot asking stupid questions). Again, thanks.

    At any rate, my plan was to have engine 1 alternator to the house batteries and engine alternator 2 to the starter battery. Worse case scenario I see is engine 2 failure and overtime no charge to the starter battery. I could then switch over to the house batteries at the Perko switch for starting.

    I would think I'd be okay as long as a general rule I dedicate switches and batteries appropriately. Granted, I haven't yet looked at the schematic yet. Again, many thanks.

    I have twin Mercruiser 470's w/ Alpha I outdrives. I've heard a lot of good and bad things about these engines, with most people saying that they are awesome if running correctly and properly maintained. I'm in the process of an upper end rebuild on the stbd engine right now and plan to address known issues with the engines ... built-in stator w/ water-cooled voltage regulator vs bolt-on alternator and 3" heat exchanger vs 4" heat exchanger.

    I purchase the boat last Spring and becuase of a few problems really didn't get a chance to use it as planned. I'm taking the time this winter to get it all squared away ... at least that's my hope.


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