I'm installing a Perko 2-battery switch on my fiberglass boat. I watched a couple of videos on YouTube and the tech kept referring to a "common ground".
First of all, even while we will see the term being used in product schematics, etc........ there is no "ground" in a 12 vdc system. Only Positive and Negative.
The term "Ground" refers to "Earth Ground" as in home and industrial Alternating Current.
What we have on our boats is a "system negative common" point, of which is most often the engine block.
To prevent excessive Negative cable/wire connections at the batteries, a system neg common terminal block can be added. The video showed him connecting the black (ground) battery cables to a connection that was not the negative post on either of the battery posts but rather, this "common ground" connection.
I would like to see this video.
Everything else made sense, but now I'm thinking that I connected my Perko switch up incorrectly. If I need to install on of these "common ground" posts somewhere, how do I do it?
Your Perko MBSS will NOT have a Negative point of connection on it...... it will have three terminals only.
.... terminal #1 for the cranking battery Positive
.... terminal #2 for your house battery bank Positive
...."common" terminal for the cable that connects to the engine's starter motor solenoid.... as per post #5.
Each battery bank will make it's own Negative connection to the System Negative Common point.
Any power taken from MBSS terminals #1 or #2 will be Un-Interruptible. In other words, when you leave the boat unattended and with the MBSS turned to OFF, these terminals will still be HOT.
If you moor this boat, the #2 terminal would be a great place to power your main bilge pump float switch!
Any help here would be appreciated !