Isolate House Power From Start Power

[Boilers2000]

I want to add a second battery and was going to go with the Blue Seas ACR. I have a 92 SeaRay 200BR with a Mercruiser 4.3LX Engine. Looking at my wiring diagram it appears that there is a red/purple wire from the alternator to the harness and the harness to the cockpit that provides power to the fuse panel but also show connecting to the ignition (i terminal). This red/purple wire appears to also got to the starter salve solenoid in the engine compartment. Is the correct way to run a blue seas to:
1. run a new wire from the fuse panel to the Blue seas system that is powered by the house battery
2. remove the red/purple from the fuse panel and splice with red/purple that runs to the i terminal of of the ignition switch. In the service manual this is this red/purple is straight to the igniton switch with a note that is is where you would add a fuse panel.

Any insight is appreciated.

Thanks

 

[H20Rat]

Why are you adding a second battery? The vast majority of the times it is because someone either wants to isolate a trolling motor or stereo system. It is far easier to move the items you want to battery #2 than to move your entire fusebox to it.

In the case of the radio/amp, just run the power wires of those items directly to battery #2 (with a fuse or fuse box of course), and leave the original wiring alone.

 

[CaptainSteveo]

I want to add a second battery and was going to go with the Blue Seas ACR. I have a 92 SeaRay 200BR with a Mercruiser 4.3LX Engine. Looking at my wiring diagram it appears that there is a red/purple wire from the alternator to the harness and the harness to the cockpit that provides power to the fuse panel but also show connecting to the ignition (i terminal). This red/purple wire appears to also got to the starter salve solenoid in the engine compartment. Is the correct way to run a blue seas to:
1. run a new wire from the fuse panel to the Blue seas system that is powered by the house battery
2. remove the red/purple from the fuse panel and splice with red/purple that runs to the i terminal of of the ignition switch. In the service manual this is this red/purple is straight to the igniton switch with a note that is is where you would add a fuse panel.

Any insight is appreciated.

Thanks

Why are you adding the second battery? Is it for backup in case your primary battery fails, or are you trying to run certain things off a different battery. I don't have much experience with the later, but if you want a backup the easiest way to go is to get a Perko switch and connect both batteries to it. I have one and I can switch between each battery by changing the switch from #1 to #2.

 

[Boilers2000]

it's the latter, I want to isolate stereo, lights, bilge blower from the starting battery. Blue Seas makes a switch and ACR that automatically charges both batteries without having to switch back and forth.

 

[Boilers2000]

Why are you adding a second battery? The vast majority of the times it is because someone either wants to isolate a trolling motor or stereo system. It is far easier to move the items you want to battery #2 than to move your entire fusebox to it.

In the case of the radio/amp, just run the power wires of those items directly to battery #2 (with a fuse or fuse box of course), and leave the original wiring alone.

It's one of the small 8 or 10 fuse blocks under the console with radio, lights, bilge, blower, horn. I want to isolate that entire circuit on it's own battery. thinking out loud, where should the bilge be tied too? Starting battery or house battery?

 

[dingbat]

First thing I did when I bought my boat was to separate the ignition circuit from the rest of the boat. Nothing on my boat is powered through the ignition switch. The wiring wasn't big enough to support the load anyhow.

When I installed my ACR, I moved everything from the starting battery over to House battery except for the ignition and bilge pump which is wired to both batteries for capacity reasons. I also added a circuit and fuse panel to starting battery to power my primary navigation devices, Chart plotter, Fish finder, VHF and Radar.

Everything else, navigation lights, lightening, stereo, backup chart plotter, fish finder and VHF is wired to house battery.

Don't understand your comment about the Blues Seas system powered by the house battery. The Blues Sea system is nothing more than a voltage sensitive mounted between the starting and house battery.

Once the ignition battery is fully charged, 13.6 Volts, the ACR closes and routes the charging current over to the house battery. When the ignition battery drops below 12.75 V, the ACR opens, disconnecting the charge current from the house battery.

 

[Boilers2000]

I meant run a new wire to the Blue seas switch that we be the side of the switch for the house battery. I was going to use the kit that is a switch and ACR combo. So for your set-up you have to hot's going to the bilge pump from each battery, regardless of ACR or Switch? do you just use an ACR or do you have a switch that allows for combining of batteries too?

 

[Scott Danforth]

on my current resto-mod.....I re-wired everything, running dedicated 6 gauge and 4 gauge power to the helm wiring.

much like dingbat, the key switch only powers some relays now

the trim/tilt is still hot all the time

the ignition switch trips 2 40 amp VF4 relays and 2 100 amp solid state relays.

the pair of 40 amp relays are what powers the engine related ignition stuff...... they are paired for redundancy. the gauges, fuel pump, and engine ignition run off that buss. total amp draw is under 12 amps

one solid state relay comes on for navigation lights (except all-around light) horn, electronics, cockpit power outlets, manual bilge, etc. total amp draw normally is about 5 amps, however if all the power outlets were to run, I could see up to 70 amps

one solid state relay comes on with the auxiliary side of the switch. this runs the all-around light, the radio and amp, the cabin power outlets. total amp draw normally is about 12 amps, however if all the power outlets were to run, I could see up to 60 amps

the auto bilge circuit and the cabin lights are wired to the hot buss

Prior to that, the ignition switch powered the dash, ignition, radio, lights, horn, etc. and there was a 30 amp switch on the dash for normal house loads (separate wiring)

 

[dingbat]

I meant run a new wire to the Blue seas switch that we be the side of the switch for the house battery. I was going to use the kit that is a switch and ACR combo. So for your set-up you have to hot's going to the bilge pump from each battery, regardless of ACR or Switch? do you just use an ACR or do you have a switch that allows for combining of batteries too?

I actually have two bilge pumps. One wired to each battery.

I run deep cycles for both start and house batteries. The on-off-combine switch allows me to combine both batteries for those cold winter mornings when I need a little extra cranking power.

 

[Boilers2000]

Got it, that makes more sense. I went and looked at the wiring last night and I think I've isolated it all. My battery power run is red wire from battery to starter/solenoid, red wire from Starter to circuit breaker. Out of the circuit breaker the wire becomes red/pur and splits 3 ways, 1 red/pur goes to sensing terminal on alternator, 1 red/pur runs to the slave starter solenoid, 1 red/pur runs to fuse panel under dash. On the fuse panel is an ignition post and that runs to the key. When the key is in run continuity between the red/pur and purple wires provides power to the instruments which runs back through the harness to the excitation terminal on the alternator and provides the 12volts the alternator needs when starting. when the key goes to start the yel/red get power and that runs to the throttle then runs to the spade terminal on the slave solenoid. This causes the slave solenoid to close and power from the red/pur mentioned above to close and provide power to a yel/red that runs to the starter/solenoid (this is a heavier gauge and connects to the post, not the spade terminal that the higher gauge one mentioned earlier is connected to) and this is the power to start the engine. If the above is correct, god I hope it's right, I think to add a 2nd battery I would need to run a new red purple from the new battery to the fuse panel and cap the existing one and set aside. This would supply power for accessories, 12 v to the alternator at start to the excitation terminal, and power to close the starter slave solenoid so that power from the starting battery can start the engine. I guess the other thing i could do is add another fuse panel under the dash run a new wire to the new fuse panel and pick and choose what gets plugged into the accessory or starting fuse panel. Does this sound right? Partially leaving here so I can remember later as well. The rest of the setup is connecting existing wires to the ACR and the Switch. TIA for any input or advice. Thanks!

 

[dingbat]

Got it, that makes more sense. I went and looked at the wiring last night and I think I've isolated it all. My battery power run is red wire from battery to starter/solenoid, red wire from Starter to circuit breaker. Out of the circuit breaker the wire becomes red/pur and splits 3 ways, 1 red/pur goes to sensing terminal on alternator, 1 red/pur runs to the slave starter solenoid, 1 red/pur runs to fuse panel under dash. On the fuse panel is an ignition post and that runs to the key. When the key is in run continuity between the red/pur and purple wires provides power to the instruments which runs back through the harness to the excitation terminal on the alternator and provides the 12volts the alternator needs when starting. when the key goes to start the yel/red get power and that runs to the throttle then runs to the spade terminal on the slave solenoid. This causes the slave solenoid to close and power from the red/pur mentioned above to close and provide power to a yel/red that runs to the starter/solenoid (this is a heavier gauge and connects to the post, not the spade terminal that the higher gauge one mentioned earlier is connected to) and this is the power to start the engine. If the above is correct, god I hope it's right, I think to add a 2nd battery I would need to run a new red purple from the new battery to the fuse panel and cap the existing one and set aside. This would supply power for accessories, 12 v to the alternator at start to the excitation terminal, and power to close the starter slave solenoid so that power from the starting battery can start the engine. I guess the other thing i could do is add another fuse panel under the dash run a new wire to the new fuse panel and pick and choose what gets plugged into the accessory or starting fuse panel. Does this sound right? Partially leaving here so I can remember later as well. The rest of the setup is connecting existing wires to the ACR and the Switch. TIA for any input or advice. Thanks!

My boat’s manufacturer wires the accessory panel separate from the ignition circuit. Just moved that feed from ignition over to house on the switch

To power the navigation instrumentation, I ran a 12 gauge, duplex wire from ignition side to the helm and installed a 12 circuit fuse block to consolidate the feeds to the electronics.

 

[Boilers2000]

I wish my Searay would have been wired that way. Probably want to keep the ignition circuit on the starting battery. Assume if you drain the accessory battery you can't start the engine, even with a combine switch because the voltage would be too low? I believe when combined the batteries are in parallel and the voltage averages between the two (dead + charged = 6v) Thanks for walking through this with me, this has been a good learning experience on the boat circuitry!

 

[Scott Danforth]

a 12 volt battery is fully discharged at 12 volts and fully charged at 13.6 volts

batteries drained below 12 volts is not good for the longevity of the battery. a battery at 6 volts would indicate that the batteries may have dead cells.

BTW, you need a minimum of 9 volts to create spark, and you need 12 volts or more to crank the motor

 

[Boilers2000]

Thanks for reminding me of that. Gut check my math my manual recommends 450CCA on a 90 AH battery, or the battery can supply 12 minutes of 450 amps. If you combine a dead battery (12v) and a fully charged (13.6v), do you end up with a combo at 50% charge, and how does that impact the Amp hours? Is it linear so now are only 45 Amp Hours available? Just wondering if I rewire the ignition circuit to make sure it's tied to the starting battery or use the exiting circuit and let it all go to the house battery. Only thing that would run when not cruising is occasionally the bilge (3A draw) and a non-amped 55Watt Stereo (5A draw). I think I would have to run those continuously for 6 hours to draw down half the capacity of the house, and that would be enough to start the boat and and open the starter slave solenoid. Thanks

 

[dingbat]

Gut check my math my manual recommends 450CCA on a 90 AH battery, or the battery can supply 12 minutes of 450 amps.

That is incorrect. CCA (number of amps for 30 seconds above 7.2 V) is a measureless measure of power for this exercise. Your battery is capable of storing / providing 90AH of current before falling below 10.5 V. You need a lot more than 10.5V to start your motor.

If you combine a dead battery (12v) and a fully charged (13.6v), do you end up with a combo at 50% charge, and how does that impact the Amp hours? Is it linear so now are only 45 Amp Hours available? Just wondering if I rewire the ignition circuit to make sure it's tied to the starting battery or use the exiting circuit and let it all go to the house battery.

13.6 V is the typical charging system output The voltage of a "rested" battery is noted below.

What happens when you combine a fully charged and a dead battery depends on a number of factors. If the voltage is low because of a dead cell or shorted internally, you could end up with two dead batteries.

Also bearing in mind that the 90 AH is for a new battery. That number will decrease over time. Personally, I would never depend on combining batteries as a strategy. Too many scenarios could spell trouble.

Fished with a guy last fall that installed two brand new Grp. 31 AGM batteries the day before. Long story short. Spent 2 hours tracking down a new battery at 6:30 Sunday morning so we could go fishing.

One battery shorted internally dragging both down. Didn't make any sense to me while troubleshooting at the time. Never got a straight answer on what his mechanic found the problem to be. I suspect he did something stupid that he didn't want to admit too, i.e tied the batteries together somewhere other than the battery switch.

State of Charge	Sealed or Flooded Lead Acid battery voltage	Gel battery voltage	AGM battery voltage
100%	12.70+	12.85+	12.80+
75%	12.40	12.65	12.60
50%	12.20	12.35	12.30
25%	12.00	12.00	12.00
0%	11.80	11.80	11.80

 

[Boilers2000]

Good info, really appreciate the time, thought and input. I guess if I am going to go through the effort the right way to do it is to isolate the ignition circuit from the house circuit. Starter Battery will power ignition circuit, and starter, House Battery will Power everything else (radio, lights, Bilge, Blower). Since the two fuse panels will be next to each other under the console if i got in a jam I could swap the bilge and blower wires to the Starter battery fuse panel. Anything else I am potentially missing? Thanks again for the help!

 

[JASinIL2006]

I wired my blower to the start battery. I figured if the blower won't run, I'm not going to be starting the engine anyway...

 

[dingbat]

I wired my blower to the start battery. I figured if the blower won't run, I'm not going to be starting the engine anyway...

The vast majority of times, motors fail shorted or leaking to ground. I’ve lost two bilge pumps this way.

A dead short will trip the breaker if so equipped, but a leak to ground may not, draining the battery in the process.

With the blower wired to the house battery, you have option to start the motor w/o the blower in an emergency. You don’t have that option with a dead starting battery.

 

[Boilers2000]

My thought was keep the start battery circuit as simple/factory as possible, to limit potential of stuff like you mentioned. In the case of a dead house battery I could always reach under the console and and swap the bilge and blower from the house fuse box to the start fuse box to pump or blow

 

[JASinIL2006]

The vast majority of times, motors fail shorted or leaking to ground. I’ve lost two bilge pumps this way.

A dead short will trip the breaker if so equipped, but a leak to ground may not, draining the battery in the process.

With the blower wired to the house battery, you have option to start the motor w/o the blower in an emergency. You don’t have that option with a dead starting battery.

Sure, just flip the battery switch to BOTH. With a two battery setup isolated via ACR, I suppose much of this is academic. The real advantage of that kind of system is that if one battery is drained, for whatever reason, the second battery is isolated until you choose to combine.