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Common grounds-important? BEP cluster.

Old 07-17-2014, 04:20 AM
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Question Common grounds-important? BEP cluster.

Are common grounds important or required? What necessary purpose is served?

BEP batter distribution cluster for 3 batteries. The installation diagram shows all three batteries, the negatives of both motors, and the negative from my main house bus all hooked together on a terminal bus.

Right now each motor negative cable goes to its own battery. (Positives run thru switch). House ground only goes to the main bus. (House positive goes thru switch before it goes to main bus)
Old 07-17-2014, 04:33 AM
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Things will only work when connected to both positive and negative from a single battery. If you don't have a common ground you can't do things like use the second battery as a back up starting battery.
Old 07-17-2014, 04:42 AM
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Originally Posted by stiletto View Post
Things will only work when connected to both positive and negative from a single battery. If you don't have a common ground you can't do things like use the second battery as a back up starting battery.
So, my parallel switch won't work? So you think that would affect the vsr in any way? The charging of my house battery has been an issue, even though I know that the voltage on at least one of my start batteries is above the 13.7 needed to close the relay and charge the house.
Old 07-17-2014, 05:00 AM
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are you sure the battery grounds arent tied together?
Old 07-17-2014, 05:30 AM
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Originally Posted by Akgoff4 View Post
So, my parallel switch won't work? So you think that would affect the vsr in any way? The charging of my house battery has been an issue, even though I know that the voltage on at least one of my start batteries is above the 13.7 needed to close the relay and charge the house.
Yes, your parallel switch won't work and your VSR won't work. You are only connecting 1 of the 2 wires needed to connect the house to the starter, and 1 of the 2 wires needed for the VSR. You are best served by jumping these grounds together and making a common ground.
Old 07-17-2014, 06:22 AM
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If you are switching house loads between the two batteries the grounds are connected somewhere. I prefer to connect them at the batteries and run from there to my ground point for the vessel and to each engine.

Jim
Old 07-17-2014, 05:44 PM
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Question "Jumping grounds together "

Originally Posted by stiletto View Post
Yes, your parallel switch won't work and your VSR won't work. You are only connecting 1 of the 2 wires needed to connect the house to the starter, and 1 of the 2 wires needed for the VSR. You are best served by jumping these grounds together and making a common ground.
I got my head back in the bilge and looked more closely at the nest of wires.

The negative terminals of all 3 batteries are connected. But, as previously posted, Each motor's ground is connected to its respective battery. The negative house distribution bus only connects to the house battery's neg post.

Will this work? Or, should I run a separate cable from each battery to a bus and also run the motor neg wires to that same bus along with a cable from the house distribution bus? (Six cables converging on one bus)
Old 07-17-2014, 05:55 PM
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Originally Posted by Akgoff4 View Post
I got my head back in the bilge and looked more closely at the nest of wires.

The negative terminals of all 3 batteries are connected. But, as previously posted, Each motor's ground is connected to its respective battery. The negative house distribution bus only connects to the house battery's neg post.

Will this work? Or, should I run a separate cable from each battery to a bus and also run the motor neg wires to that same bus along with a cable from the house distribution bus? (Six cables converging on one bus)
No, if all the negative posts of the battery are connected, then you have a common ground.
Old 07-18-2014, 05:35 AM
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Did you ground the small black wire on the cluster?
Old 07-18-2014, 02:45 PM
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Originally Posted by djhnsn View Post
Did you ground the small black wire on the cluster?
No. It is taped off, like the small red wire.
Old 07-18-2014, 04:40 PM
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if the vsr's don't have a ground they will not work. they probably have a light when they are connected (charging) to show they are working. the acr's do.
Old 07-19-2014, 06:22 PM
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Originally Posted by Akgoff4 View Post
No. It is taped off, like the small red wire.
That black wire needs to be grounded otherwise the acr will not close and charge the house battery.
Old 07-20-2014, 06:31 AM
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Originally Posted by Akgoff4 View Post
The negative terminals of all 3 batteries are connected. But, as previously posted, Each motor's ground is connected to its respective battery. The negative house distribution bus only connects to the house battery's neg post.
As someone else said - if the negative terminals of all 3 batteries are connected to EACH OTHER (ie a wire connecting each starting to the house) then you have a common ground. Make sure that's a suitably heavy gauge and you'll be fine.

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