1989 Trophy, Adding 2nd Battery

[LakeMichiganBoater]

I am trying to add a second battery to my 1989 Bayliner Trophy 2459 and I'm trying to figure the best way to wire it up.

Currently I have a starting battery and a deep cycle battery. I would like the starting battery to only be hooked up to engine (alternator, starter, coil, etc...) and the deep cycle to everything else, namely the fuse box in front of driver controls. The battery's will be connected to each other in the rear by the engine using a smart battery combiner (12.7+ connected, 12.6 or less then disconnected).

The issue I'm having is there is only one main positive wire going to the starter solenoid. Where does the front fuse panel tap into the start solenoid or engine harness? I would like to locate that so I can attach that wire to the deep cycle battery.

 

[alldodge]

Don't know where the Bat is tapped in your boat, have to trace wires to find out. Most come off the starter solenoid post, others off the Bat

The fuse block will have one main wire feeding it, follow this back to where it connects

 

[Lou C]

I had that same kind of wiring set up and what I did was simply use a pair of group 27 dual purpose batteries and a 1,2, both & off switch. I added a digital voltmeter on the dashboard to better monitor battery voltage and when I run the boat, I will alternate using # 1 , & # 2. The digital voltmeter will give me a more accurate reading on the voltage of each battery.

 

[dingbat]

I am trying to add a second battery to my 1989 Bayliner Trophy 2459 and I'm trying to figure the best way to wire it up.

Currently I have a starting battery and a deep cycle battery. I would like the starting battery to only be hooked up to engine (alternator, starter, coil, etc...) and the deep cycle to everything else, namely the fuse box in front of driver controls. The battery's will be connected to each other in the rear by the engine using a smart battery combiner (12.7+ connected, 12.6 or less then disconnected).

The issue I'm having is there is only one main positive wire going to the starter solenoid. Where does the front fuse panel tap into the start solenoid or engine harness? I would like to locate that so I can attach that wire to the deep cycle battery.

What motor are you working with?
Typically there is a 40 amp, push button circuit breaker protecting the feed to the helm/accessories
My CB next/behind to the starboard (starting) battery

 

[LakeMichiganBoater]

What motor are you working with?
Typically there is a 40 amp, push button circuit breaker protecting the feed to the helm/accessories
My CB next/behind to the starboard (starting) battery

OMC 5.8 stern drive

 

[Lou C]

Wired pretty much the same way as my ‘88 OMC 4.3 then. I could not come up with an easy way to separate the loads so I just use the same battery on each side & alternatively switch use of batteries. Just don’t leave it on Both because if one battery is going bad it will drain the other one. Only use both if either is too weak to crank the engine. The idea is to keep them isolated.

 

[airshot]

Not an electrician here, so only a suggestion...why connect them at the back? On my boat the start battery is for engine only and my deep cycle controls all the electronics...lights, fish finder/ gps, ship to shore, accessory outlets, for phone charger and minnow bucket aerator, fm radio...everything...never have I drained that deep cycle battery even after 8 hours using everything. I just put the deep cycle on a charger/ maintainer when I park the boat. Much better for the deep cycle battery than charging off the engine alternator. Just a thought....

 

[LakeMichiganBoater]

Not an electrician here, so only a suggestion...why connect them at the back? On my boat the start battery is for engine only and my deep cycle controls all the electronics...lights, fish finder/ gps, ship to shore, accessory outlets, for phone charger and minnow bucket aerator, fm radio...everything...never have I drained that deep cycle battery even after 8 hours using everything. I just put the deep cycle on a charger/ maintainer when I park the boat. Much better for the deep cycle battery than charging off the engine alternator. Just a thought....

Just like to have both charge off the alternator. The load of the equipment is low (10 gauge, from the diagram I see) but the battery to battery connecting is high load, made sense to keep the batteries close together to minimize that length of high amp cable. Also they will both charge with one battery maintainer using the smart battery combiner.

So I did find a wiring diagram and it looks like the power comes from the engine to the equipment by the means of a 10 gauge red and purple wire. I'm assuming if I just disconnect that from the harness at the engine and tie it into my second battery I should be good to go. Does that sound right?

 

[dingbat]

So I did find a wiring diagram and it looks like the power comes from the engine to the equipment by the means of a 10 gauge red and purple wire. I'm assuming if I just disconnect that from the harness at the engine and tie it into my second battery I should be good to go. Does that sound right?

Looks like you have to deal with a connection at key switch B and the bilge pumps as well.

 

[LakeMichiganBoater]

Yeah I see those connections, but I want to interrupt the 12v supply from the red main line from the engine to the fuse box. I think those ones run separately on their own.

 

[dingbat]

Yeah I see those connections, but I want to interrupt the 12v supply from the red main line from the engine to the fuse box. I think those ones run separately on their own.

Not what your schematic shows.
Both circuits back feed the other.
Not good

 

[LakeMichiganBoater]

Not what your schematic shows.

Both circuits back feed the other.
Not good

Ah, I see what you're saying. Even if I disconnect the red/purple 12v supply at the engine, there is the scenario where the bilge switch is on and the float valve is activated that it would backfeed from one battery to the other and be way to much amperage for that wire... probably just blowing the inline fuse.

So I would have to tap into the red/purple at the engine (to secondary deep cycle battery) and also attach the bilge pump float switch dedicated line to the same battery to avoid this.

Seems like the other dedicated line goes to the trim... not sure how that would backfeed as it does not appear to be connected to any other supplies.

 

[airshot]

Just like to have both charge off the alternator. The load of the equipment is low (10 gauge, from the diagram I see) but the battery to battery connecting is high load, made sense to keep the batteries close together to minimize that length of high amp cable. Also they will both charge with one battery maintainer using the smart battery combiner.

So I did find a wiring diagram and it looks like the power comes from the engine to the equipment by the means of a 10 gauge red and purple wire. I'm assuming if I just disconnect that from the harness at the engine and tie it into my second battery I should be good to go. Does that sound right?

Keep in mind the deep cycle will probably not fully charge on just the alternator, most mfgrs of deep cycle batteries recomend not to use an alternator to charge for longest service life. Your call...

 

[LakeMichiganBoater]

Keep in mind the deep cycle will probably not fully charge on just the alternator, most mfgrs of deep cycle batteries recomend not to use an alternator to charge for longest service life. Your call...

Understood, it will be on a maintainer when not in use, just would like to have the alternator charging as well while in use.

 

[Lou C]

I think it’s just easier & more than adequate to do what I did. 2 dual purpose gp 27 batteries a simple switch & alternate use of batteries. I have a Garmin GPS/fish finder, Sound system & 2 VHF radios (one hard mount one rechargeable). Standard ARCO alternator. No problems keeping the batteries charged & this boat lives on a mooring all season no shore power no maintainer.

 

[dingbat]

Ah, I see what you're saying. Even if I disconnect the red/purple 12v supply at the engine, there is the scenario where the bilge switch is on and the float valve is activated that it would backfeed from one battery to the other and be way to much amperage for that wire... probably just blowing the inline fuse.

There is also a scenario where a bilge motor fails (burnt winding) tying the two circuits together.
Wouldn't worry too much about the battery equalizing but you'll be surprised to come out in the morning to find the nav light is on (very dim) when the start battery switch is off.
Been there, done that.

So I would have to tap into the red/purple at the engine (to secondary deep cycle battery) and also attach the bilge pump float switch dedicated line to the same battery to avoid this.

The easy way is to put a diode on both lines to prevent back feeding the circuit.

Seems like the other dedicated line goes to the trim... not sure how that would backfeed as it does not appear to be connected to any other supplies.

My mistake.....wiring diagram doesn't use same nomenclature we do.

Keep in mind the deep cycle will probably not fully charge on just the alternator, most mfgrs of deep cycle batteries recomend not to use an alternator to charge for longest service life.

Nothing to do with the suitability of an alternator to charge and everything about run time.

Running 15 minutes out to the sand bar, blasting the radio all day then running 15 minutes back to the marina is no going to get adequately charge any battery, let alone a deep cycle that doesn't like to sit discharged for any length of time.

I keep two (2) Grp. 27 batteries (108 AH ea.) fully charged with a outboard with a 30 amp charging system but..........I put 6-7 hours of run time (6 x 30 amps = 180 AH) in every time I'm out.

Got 10 years out of the last pair of deep cycles before I swapped out as PM

 

[LakeMichiganBoater]

So I tapped the deep cycle battery into the red/purple line near the starter solenoid and disconnected it from the exiting path and it seems to have worked and doing what I want. I just need to do some more verification to make sure there are no other crossovers from one battery to the other when they combiner separates them, I fear there may be aftermarket connections.

 

[Lou C]

I use this simple way of keeping both charged with the switch…#1 on odd # days, #2 on even # days. I usually get about 7 years out of my batteries before they won’t hold a charge…

 

[dingbat]

I just need to do some more verification to make sure there are no other crossovers from one battery to the other when they combiner separates them, I fear there may be aftermarket connections.

Simple........remove positive cable from either battery and check for continuity to the Ground terminal on the other battery.

 

[alldodge]

Red/Purple wire is after the 50 amp breaker