Battery switch with electronics

[VonDog]

I've got a messOne fuse panel for GPS, FF, and docking lights are powered through the "ALL" selector on the dual switch. Another box with car type fuses is wired to Batt #2, pos. with a "short stop" but the neg. runs to a ground bus not attached to anything and zipp tied in a baggy. This runs the instrument panel switches like courtesy lts, bilge, livewell, horn, and nav lts. The third and final fuse panel is located in the electronics box under the T-Top and is powered by Batt #1 pos and neg. This runs the stereo and VHF radio.

Confused? My question is - Can I attach the battery pos wires from the two batteries to the "ALL" selector on the switch or should I take the wires off batt #1 and hook them to the fuse panel that runs off the "ALL" selector? And would this allow the whole system "OFF" when the selector sw is turned off? Any help is appreciated!

 

[ButchC]

Re: Battery switch with electronics

Hi,

The MBSS has four positions; 1, 2, All and off. 'Normally' the starting battery is connected to the 1 post. House battery(ies) are connected to 2. The third post on the switch is selected by the switch. If the switch is on 1 then battery 1 (normally starting) is connected to the third post. If the MBSS is on 2 battery 2 (house) is connected to the third post. If ALL is selected then both battery banks are connected to the third post. Often a dual output battery charger is connected to to the MBSS switch posts 1 and two. Also a bilge pump float switch may be connected to a post 1 or 2 so it is directly tied to a battery and will operate the pump even when the main switch is off. The starter motor cable is connected to the center (third post).

I'm not sure how your seeing something that runs power in ALL but not on either 1 or two.

Butch

 

[Silvertip]

Re: Battery switch with electronics

You need a rewire and eliminate at least two of the three fuse panels. If the remaining panel doesn't have enough circuits, replace it with one that does. With a dual battery switch and dual batteries, every circuit on the boat ideally would be powered from the COM terminal on the switch. You therefore select which battery will power the stuff when anchored or running. OFF turns everything off except the bilge pump which is the ONLY thing that would typically be wired directly to either one of the batteries. The way it's wired now you really wouldn't need the switch since stuff seems to be wired directly to the batteries which defeats the purpose of the switch anyway.

 

[dingbat]

Re: Battery switch with electronics

You can do what you describe but that leaves you with a single point of failure that will take down everything. Probably not a concern for an inshore boater but it's a scenerio I would not want to face 30 miles out.

I have 3 fuse boxes as well. All the boat functions (running lights, bilge, live well, etc.)are wired to the switch/ circuit breaker panel at the helm that is wired into the com switch.

A second ATC fuse block which wired directly to battery 1 is used for the electronics at the helm for GPS, primary VHF, and the fish finder.

A third ATC block in the overhead is wired directly to battery 2 and is used to supply power to the CD player, the back-up VHF, a back-up GPS and the radar dome.

The other thing to consider, do you have any equipment that requires constant power for it?s memory?

 

[Silvertip]

Re: Battery switch with electronics

A battery switch is not the only single point of failure on a boat. Failure of a battery or anything connected to it is a single point of failure for those items. The electrical component "least likely" to fail is the switch itself. These are stout devices. By having three fuse panels you increase the odds of a failure, not decrease them. If reduction in length or number of wire runs is of importance a number of fuse panels scattered about the boat is certainly one way to accomplish that. But for reliability, the fewer number of components provides the best reliability.

If all one expects from the switch is the ability to switch the house battery over to serve as an engine start battery, then by all means do what you feel you need. But that defeats the purpose of the switch which you then don't need at all. A set of jumper cables will do nicely in that case and a simple $6.00 knife switch at each battery will save some heavy duty wiring and still provide the OFF function.

 

[dingbat]

Re: Battery switch with electronics

A battery switch is not the only single point of failure on a boat. Failure of a battery or anything connected to it is a single point of failure for those items. The electrical component "least likely" to fail is the switch itself. These are stout devices. By having three fuse panels you increase the odds of a failure, not decrease them. If reduction in length or number of wire runs is of importance a number of fuse panels scattered about the boat is certainly one way to accomplish that. But for reliability, the fewer number of components provides the best reliability.

If all one expects from the switch is the ability to switch the house battery over to serve as an engine start battery, then by all means do what you feel you need. But that defeats the purpose of the switch which you then don't need at all. A set of jumper cables will do nicely in that case and a simple $6.00 knife switch at each battery will save some heavy duty wiring and still provide the OFF function.

In my case, the battery switch is used for no other purpose that to isolate or combine both batterys for starting purposes.

 

[VonDog]

Re: Battery switch with electronics

Thanks for the help guys. I've managed to rewire all electronics etc. off one fuse panel connected to the common on the switch and everything works beautifully. The original panel wiring from the boat manufacturer ie. switches for bilge, livewell, nav lts, horn and guages are run off a fuse panel that is directly fed from Battery #2. The + red wire has a "short stop" breaker at the battery terminal. Is it ok to hook this to the common on the dual switch? And do I leave the negative black wire hooked to the battery or move it someplace else? Again - Thanks

 

[Silvertip]

Re: Battery switch with electronics

I rest my case since in your situation, the single point of failure your were so concerned about is still a single point of failure. Only in your case if the switch fails you are dead in the water as the engine wouldn't start (unless you had a set of jumper cables or did some on-water rewiring). There are many ways to use a switch and this is just one of them. Not using it to full advantage means you lose a great deal of versatility - not only for the engine but for the accessories as well.

 

[dingbat]

Re: Battery switch with electronics

If you had the same set up how would you wire them up for full redundancy?

Grp. 27 Deep cycle batteries x 2
GPS x 2
VHF x 2

 

[VonDog]

Re: Battery switch with electronics

I posted a new thread with updates of which I've had no responses or at least any responses that were helpful. Just to let you know silvertip, I figured out my whole wiring system and made all the necessary changes in order for my boat to operate with full efficiency and ease. If I go dead on the water, I have a backup system that would make even a hardened sailor sing for joy. Even and old aviation electrician's mate 30years ago can still remember a few things the service has taught him!!!