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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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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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.
 

DennisG01

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#10
These engines each have an auxillary charging lead - use one of those for the house bank.

FYI... technically, we don't have "alternators". We have a stator and rectifier which work when the flywheel is spinning.
 
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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
 
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#16
Spent 4 days in Fl working on the boat.
Replaced several switches and breakers at the helm panel. New Wire Marine switches and only needed very minor mod to the holes with a small file. Have more to do but need custom labels.
Replaced the factory charger with Pro Nautic 12/30 3 bank charger. Getting the original charger out was a nightmare, had to shave insulation off the livewell to eventually get it out. Each leg is protected with a 40 amp mrbf fuse in a 3 fuse block. Its working great. It was a lesson in dc voltage drop problems with weak batteries and essentially no charging. Once the batteries showed 14 volts on the charger the bilge pumps ran much better. The bilge pumps ran ok on the float switches but not from the helm switches before charger and ran great on both after.
Cleaned up wiring at the battery bank, adding a negative bus centralized things and looks much better. I will add a dc pos fuse block next trip the clean up various dc loads which run directly from the batteries.
Next trip will also replace the battery switches. I plan to add a 4th switch for the aux charge wires. That way I can use either engine to charge the house batteries. I saw a post where the op had placed both aux wires on the house batteries, I thought this was a no no.
I did eliminate the ac going to the helm temporarily and currently the only ac load connected to the shore power inlet is the battery charger. This does cause some concern. It temporarily eliminated the galvanic isolater but since the boat is on a lift out of water there is no circuit to other boats or safety grounds. It also eliminated the reverse polarity indicator and a breaker between the shore power and charger. All 3 need fixing soon. My concern is with the helm ac/dc panel it is old and has significant corrosion potentially allowing current leakage and corrosion or worse. I do not see myself using any of the ac loads at the helm or cabin so something has to be done there.
Lastly the charger has the safety ground green wire from shore plug attached and the chassis ground wire is bonded to the negative bus I added. But... I think by eliminating the ac to the helm panel I have eliminated the shore safety ground bonding to the dc negative bus. I neglected to verify this before leaving and am not sure if the ac safety ground from shore and chassis ground a connected in the charger.
I will try to post pics next time