92 Marlin electrical upgrade

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#1
Recently purchased 92 Marlin, twin Yamaha 2stroke 250's. Hull seems solid, engines run well. Electrical needs work. Currently 4 Optima blue tops wired in pairs parallel. While I would like to do a complete rewire, because we are not full time at the boat location it would take to long to complete. Plan is to clean up as best I can but use parts which can be carried over to rewire should that ever get done. Must change battery charger, looking at pro sport 20 charger. Want to remove or disable factory ac system and run dc wire to cabin and use an inverter (2000w?) for the limited ac we will need. Helm panel really needs work. Will replace all switches and what wire I can easily change. I am thinking I would prefer a remote fuse block instead of the push breakers currently being used so will need to fabricate or have fabricated a new panel. Have not decided if I will change light fixtures or just plug in led bulbs to current ones.
Any comments or suggestion appreciated.
Thanks
 

DennisG01

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#2
Inverter and AC... it sounds like you are thinking of getting rid of the AC system all together, based on what you said? That doesn't make sense. Maybe you're, instead, thinking of running 12V wires to an inverter that you mount in the cabin? That would be a waste of time and money (large gauge 12V wires are costly). Install the inverter in the bilge and just tie into the existing AC system. Done.

The ProSport is a kinda lightweight charger. I'd look into ProMariner's better line, the ProNautic series. And go with at least 30amps.
 
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#3
I did think of using the bilge, but was not sure the environment was suitable there and space requirement. The inverter I am familiar with is approx 1 cu ft in size. I will look further. Will also research chargers better. As for this project overall it is very similar to the off grid cabin I just put together in upstate NY. Solar panels, golf cart battery bank, charge controller and inverter. As a matter of fact many of my dc supplies came from the local marine store. My goal is to refurbish and simplify as best I can.
thanks
 

DennisG01

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#5
I work part time at a Sea Ray dealership (and in the marine industry for 30 years). Every Sea Ray Sundancer has it's battery charger mounted in the bilge - and they have used the ProNautic series on thousands of boats. I did the same when I replaced my charger on my Sundancer - put a ProNautic in the bilge. That was 8 years ago. Yup - it is fine to mount it there! :) (But you wouldn't want to mount it ABOVE deck where it can get rained/splashed on)
 
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#6
Trying to figure out the battery wiring on the Marlin. My assumption was that the four 12v batteries were wired in two parallel strings ie battery 1 and battery 2. The attached diagram shows that battery 1 is one starting bat and battery 2 is the second starting bat and battery 3 and 4 are the accessory batteries which can be utilized individually or in parallel. Thus essentially they are 4 independent batteries. Which brings me to my next question a replacement battery charger. The schematic seems to show 4 outputs from the on board charger. That would mean replacing it with a 4 bank charger, correct. I am also perplexed by the battery isolators as they only go to the accessory batteries , is there an assumption in the diagram i am missing.
thanks
 

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#7
I seem to have been wrong about how batteries are wired. One bat to start each engine then the other 2 ind or in parallel for house. Sure could use some help figuring out how the charging is wired, both from engines and shore power. I will need a new charger, 3 new battery switches for sure.
 

DennisG01

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#8
Nothing (unless I'm missing it) on that diagram is showing how the engine batteries are being charged. BUT, that could be because that diagram is primarily focusing on the battery switches. Are there other diagrams about "charging"?

What is your current setup? Do you currently have charging leads from the engines attached to the engine batteries and does that work properly?

If it was me, I would parallel the two house batteries... then change that "accessory battery switch" to a simple on/off switch. Then you only need a 3-bank charger. Go with at least the ProNautic 30 amp, ideally 40 amp. The two batteries that are now paralled are now one, large "bank". The charger's "house battery" + lead would go to one of the house batteries + post and the charger's negative - lead would go the other house battery's - post.
 
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#9
that was my plan exactly, glad for confirmation one question 2 engines, 2 alternators thats fine for the starting batteries, but is there an issue have 2 alternators feeding one battery (house/parallel bats). I have read a lot of confusing info on that issue. I assume that when out for a lengthy time period you would want the engines to maintain charge of house batteries.
 
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#11
Working on redo of electrical components in stern. Currently 3 bank battery, will replace charger with 3 bank 40amp pronautic, will replace battery select switches. Should i replace galvanic isolator? Is it advisable to put a 30amp gfi breaker in the line to the ac panel, thus protecting the whole boat? I plan to use pos and neg bus bars. attached is my schematic for wiring for review
thanks stern wire.jpg