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  1. #1

    Default Wiring for 2 motors, 3 batteries, 2 switches

    I'm re-commissioning our 40 year old Silverton and I'm trying to make sense of and organize the battery wiring. We bought the boat in the water 2 years ago, used it casually for the rest of that season while we assessed its needs, and we've been out of the water working on stuff since. As my thread title says, the boat is powered by twin LM318's, and there are 2 Perko battery switches and a shore power charger. I'm not sure how the charger was set up, but there were 3 batteries in the system. I assume 1 each for starting the engines and 1 for the house/bilge pumps. Other than that, there are a ton of wires that were tagged to the various batteries which I have yet to trace back. But I suspect there may be some dead-ends in there since I have already torn out a couple 5 gallon buckets worth of old, unused wiring left over from old radios and electronics, etc.. The original wiring harness seems to be intact except that the OE alternators were replaced by Delco-type 1-wire units. I have already organized the flybridge wiring by running a single hot and ground, and adding a fused panel for power distribution. I'm thinking I will end up with something similar to organize the stray leads in the engine room as well.

    I understand that with 2 alternators there needs to be some management system to prevent one alternator from overpowering the other and eventually burning it out. And I suspect that might not have been the case since as-bought, the starboard voltmeter showed a healthy output whereas the port alternator showed zero. I see some layouts online that show ACR's. Are these required for this system, or are there other ways to lay it out?

    So, having to rewire everything back to the batteries, what will my wiring look like? Is there a standard wiring diagram for this arrangement?

  2. #2
    Join Date
    Sep 2008
    Maryland - USA

    Default Re: Wiring for 2 motors, 3 batteries, 2 switches

    If its 40 years old, consideration should be given to all out replacement.....

    that said, if things are functional. its usually easiest to keep the engine harnesses as they are and use and ACR to connect the house battery for charging. there are LOTS of options/variations....its usually best to use the kISS principle...

    Any changes made should use marine grade wire and appropriate terminations....and make sure the ground cables are adequate and provide a common low resistance path between the batteries and the engine blocks...

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