2 motors, 3 batteries, 2 switches

[swampyankee]

I'm replacing an upgrading the battery setup on my old Silverton. It has twin 318s, and was equipped with a starting battery for each, along with a house battery. Somehow they were all run thru 2 Perko off, 1, all, 2 switches. The wiring was such a rat's nest I'm really starting over.
My conundrum is how to wire 3 batteries into 2 switches, and have them charge off either alternator without "crossing the streams" (Ghostbusters reference).
I found a diagram on the Perko site that would seem to work. It looks like I will have to be diligent about my switch selection since if I put both switches to "all" I would be sending both alternator charges into the same circuit. That's fine but can I be certain that I'll be charging all the batteries sufficiently. Presumably I would run the port switch on 1 to charge that starter battery, and the stbd switch on "all" to charge both that starter battery and the house battery.
I'm trying to keep it simple and avoid all sorts of ACRs and isolation switch gear etc..
Is this how its done?

 

[High Wire]

Yes that will work IF you always remember to manually switch to charge the house battery. If you look up Automatic Charging Relays or Voltage Sensing Relays, when connected properly, it will charge the house battery any time a charging source is applied to one of the start batteries. Check out Blue Seas site.

 

[Comodave]

I would go the ACR route.

 

[AusCan]

Agreed, ACR's are great. Install it and you don't have to worry about switching anything.

 

[C lectric]

The odds are you will forget to switch the battery switches thus failing to charge what needs a charge or draining what you don't want to drain.

I am not the only one to present this question "How do I know" applied to this scenario.

Most of us try to eliminate that possibility for good reason. Yes what you show is simple but sooner or later you will mess up.

 

[FF]

We have found an ACR another expensive and unrepairable piece of gear

A key switch with the auto style ACC terminal and a RV $18. solenoid turns off automatically.

Note the two parallel arrows on the drawing , these are to power the field , and are built in to the rotary switch as break before break switches.

Should some dummy turn of the engine battery switch while the alt is charging this feature will save the alt.

 

[CharlieJ]

Contrary to the comment from FF:

We have found an ACR another expensive and unrepairable piece of gear

I have installed literally dozens of the various Blue Sea System ACRs and have found them to be absolutely reliable. Yes, they are unrepairable, but my experience is that they do not fail, even on longline commercial fishing boats.

 

[swampyankee]

After careful consideration and review of various schemes I have decided to go with the layout I had posted, minus the field disconnects. This will at least get me started this season, and I can always add ACR's as time goes on.
I have always been OCD about electrical systems and the proper switching, etc. so I don't have a problem with taking the risk of conflicted alternators or batteries not getting properly charged.

 

[FF]

"so I don't have a problem with taking the risk of conflicted alternators or batteries not getting properly charged."


The simple way to avoid the risk is a Pre start checklist and an engine Secured check list.

 

[swampyankee]

"so I don't have a problem with taking the risk of conflicted alternators or batteries not getting properly charged."


The simple way to avoid the risk is a Pre start checklist and an engine Secured check list.

Checklist - check! Including unplugging the shore power cable before casting off docklines! [emoji51]