Wiring rats nest and battery layout

Discussion in 'Electrical Stuff' started by SkippersList.com, Dec 25, 2012.

  1. SkippersList.com

    SkippersList.com New Member

    Dec 22, 2012
    East Central Florida
    1980 SeaRay Express Cruiser SRV 360
    Twin 3208s - Turbo Charged
    We almost didn't take this vessel over initially due to the bypasses and work arounds but everything works, SO ...

    Last visit I went through the batteries, cleaning and servicing them and tracing the wires noting their condition and whether or not they were run correctly or rerouted or bypassed for whatever reason. Pretty much all the wires look new and thankfully rated for marine use.

    The two main 8D batteries are good but I found where the neg posts were connected from batt to batt (Not sure if this is correct or not) as are the pos posts which I'm sure isn't correct, basically the two batteries are acting as one big battery.
    The gen battery (Okay the battery I saw) I'm certain is shot but shouldn't even be in there. Currently the battery is just sitting next to the AC units behind the STBD engine with no tray so I'm certain it was an add on. There are #10s coming from the gen battery to the bulkhead battery switch and then I believe it goes in to the house batteries. We found out by accident that the radio was wired directly to the gen battery when we turned off the charger and the radio died. At this point I believe it would be better to just remove it and correct the wiring.

    I installed two marine batteries in the salon for the house batteries and I can see where the cables for the windlass and wires I believe go to a inverter or from the battery switch that went to the gen battery and then there is main cables coming from the main battery switches I assume to use for jumping the main batteries if needed.

    What I'd like to do if correct this mess so I've located the owners manual for an 81 360 SRV (that was as far back as SeaRay went) but its showing a few different wiring diagrams. So what I'm here to ask is if there is a better layout since I'm looking at redoing this mess anyway and the layouts in the manual are 30 years old. I have the two 8D main batteries and the two deep cycle/ cranking marine batteries in the salon for the house batteries and as mentioned above I'll be removing the battery I initially thought was the gen battery.

    I look after a 2000 Luhrs 36' Sport Fish that just has 2 8D and one genset battery so I'm sure there are other variations ... just hoping someone might have some input before I tackle this rat nest!

    Thanks all.
  2. Jimmy Buoy

    Jimmy Buoy Well-Known Member

    Dec 3, 2008
    Sarnia, Ontario, Canada
    2004 Formula 27PC
    twin 4.3 EFI/Bravo III Dual Prop Drives
    I'm no expert with regards to battery setups, but here's what I've found...

    Having two batteries linked together in "parallel" is quite common and is designed to create in essence, a "larger" battery. In my boat each engine has a pair of 12vt deep cycle for each main engine and a separate 12vt starter for the generator. The two paired engine batteries each power 1/2 of the DC house power as well - which is not recommended from sources outside of Sea Ray. I guess their thinking is that it is unlikely for the house to drag down both the stb and port battery banks at the same outing, so there would be one bank left to start that engine. Once started, the "emergency start" button (which links the stb and port battery banks together) would allow power to be sent to the depleted bank to start the other engine. In the event that both banks become depleted, there is always the availability to start the generator (since it has its own dedicated starter battery) and have the onboard charger/converter give the main banks enough of a charge to start one of the mains. I've never checked this, but the "emergency start" button at the helm may also tie in the generator battery to help start one of the mains.

    Most sites recommend a true starter battery/batteries dedicated to start the mains only. The house should be powered separately by dedicated deep cell batteries. The number and size (total capacity) is based on your power needs while off shore power. I'd still consider having a separate starter battery for the generator - just in case
    Last edited: Dec 25, 2012
  3. SkippersList.com

    SkippersList.com New Member

    Dec 22, 2012
    East Central Florida
    1980 SeaRay Express Cruiser SRV 360
    Twin 3208s - Turbo Charged
    Thanks Jimmy ... I pulled the schematics for my boat and there appears to be a few variations, but after reading your comment I believe I will keep a dedicated starter battery for the generator. (Just in case) I'll just secure it like it should have been to begin with.

    I have never seen two 8D batteries run in parallel for twin engines and was anticipating removing the cross wire on the positives and reinstalling the parallel solenoid the PO removed, may still install the parallel solenoid for the house batteries (Just in case)... my question now would be the charger as there is still a charging lead going to the selector switches on each battery. I need to determine if these selector switches are allowing the charger to charge the main and house batteries simultaneously or otherwise.

    Thanks for your input.
  4. mcyvas

    mcyvas New Member

    Feb 13, 2011
    great lakes
    1998 370 sundancer
    454 merc, 7.4 l
    Re: Battery switches
    twin engines, 5 batteries. 3 switches. 2 sets of 2 batteries tied together (positives are connected, neg are connected). 1 battery has own neg and positive leads.
    1 set also has neg lead going to the 1 switch which has 1,2,both choice. the single battery also has positive lead to same switch above. From this switch, a positive and neg lead leaves and heads above the engine compartment, to 2 switches with on,off starbd and on,off port.

    can someone explain to me how this is to be operated during operation. at dock, on water and under generator power ??​

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