Running on 1 battery VS 2?

[Bfun220]

#1 and #2 battery go to the switch.

[Southernboatman]

Bfun will know details better but...1 batt for engine, 1 batt for accessories. All on helm switches except for a couple of directs like bilge pump so it can kick on automatically without the switch, then also a switch to turn on if needed. Monitor allows batt switch to charge both and/or 1 at a time as required.

[Driller]

So in theory it is a better rig up. At least it would simplify the Batt 1 / batt 2 issue. Looked at one of these at my dealer the other day, it said on the packaging limited to 380 hp engines I think my 8.1 L Gi is rated 400 hp. The only issue I could think of related to engine size would be cranking amps.

[Big Block Power]

I think your 8.1gi is 380. But I haven't looked lately.

[Driller]

You're right 375 hp. My bad.

[Bfun220]

Looked at one of these at my dealer the other day, it said on the packaging limited to 380 hp engines

This rating should be just for the switch. You could always buy the correct switch for your application and then buy the rely.

[Bfun220]

The new fangled switch is on off and an override...idiot proof I guess with smart features so no more switching.

My boat has one of these "New fangled switches".
And while I was doing some garage boating today and had a thought. I dont remember seeing the relay or additional wires. So i dug into it and found the switch wired to run everything off battery #1. The only time battery #2 would be used is if I put the switch in combine position. Not a terrible set up. But battery #2 will also only charge if the switch is in the combined position. The guy I bought the boat from probably was thinking this was a good set up.
So I'll install the rely and rewire the switch next week.

[Driller]

I've been studying this some, and I think the "new fangled switch" with the ACR (automatic charging relay) is the way to go. I know my stereo will drop out when I start the engine and then re-start when the engine is running. I wonder if the current drop is causing the issue.

As I understand the relay it is only sensing 2 things. the voltages in the batteries, and whether you have the starter energized (at which time is isolates the batteries). It will charge the A battery (starter battery) to full capacity while running, and then combine to charge the B battery (house battery). Also, if one of the batteries goes to low voltage it will isolate them to keep the other from draining.

The only issue I am unsure about is this scenario. The alternator is set up to charge the A battery. The A battery goes bad so it isolates the A from the B. Now the alternator is trying to charge A and no current can be sent to B. It will go dead also. Can't figure out the set up on how the alternator is rigged.

With the old switch it simply charges which ever battery is selected, so I assume it is tied into the 1 / 2 switch.

[Bfun220]

I know my stereo will drop out when I start the engine and then re-start when the engine is running. I wonder if the current drop is causing the issue.

I would say yes, it is caused by the current drop.

[Bfun220]

As I understand the relay it is only sensing 2 things. the voltages in the batteries, and whether you have the starter energized (at which time is isolates the batteries).

It does sense the starter being energized. For this you would need to run a wire from the ignition switch to the rely.

[Bfun220]

The only issue I am unsure about is this scenario. The alternator is set up to charge the A battery. The A battery goes bad so it isolates the A from the B. Now the alternator is trying to charge A and no current can be sent to B. It will go dead also. Can't figure out the set up on how the alternator is rigged.

Your correct here only if battery A is bad and taking a charge. I believe once battery A stops charging weather fully charged or bad, battery B should start charging.

[Bfun220]

Here's a good video.
https://youtu.be/B4830QsybbM

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[Driller]

The only issue I am unsure about is this scenario. The alternator is set up to charge the A battery. The A battery goes bad so it isolates the A from the B. Now the alternator is trying to charge A and no current can be sent to B. It will go dead also. Can't figure out the set up on how the alternator is rigged.

Your correct here only if battery A is bad and taking a charge. I believe once battery A stops charging weather fully charged or bad, battery B should start charging.

It looks like to me that the line from the alternator is not hooked up to the relay. You just connect the relay to the positive terminal on each battery (according to the wiring diagram). So it is not actually switching the alternator charging from one battery to the other. It is only combining the batteries (and therefore the charge) once the A battery is fully charged. So the charge from the alternator would have to be attached to the switch on either A or B battery.

Now in this video, they have run the relay leads back to the switch, which would help facilitate the charging, but the same problem exist. Which ever terminal A or B you hook the alternator lead to will not charge the other battery if that battery goes bad. The switch will isolate both the batteries.

https//www.youtube.com/watch?v=B4830QsybbM

[Driller]

According to the wiring diagram if I read it correctly, the alternator lead is not hooked up to the relay in any of the diagrams. Only battery leads, therefore it can't actually switch the alternator charging from one battery to another, it can only combine the batteries and therefore the charge.

The line to engine is to the starter, not the alternator.

https://dh778tpvmt77t.cloudfront.net/im ... system.png

[Driller]

Here the instructions. Look at the top right of page #2