Grounding house battery

[Allure2sail]

Hi:
Not fond of the fact that the house battery relies on the grounding of the starter battery condition. Seems if you lose your starter battery ground connection the whole boat loses electrical power (not good if you need to make a distress call). I was going to ground the house battery but wads told it might create a "Ground loop" or was it called a "ground fault" and create charging problems. Has any one ever heard of this or added and extra ground off the house battery. I only know basic marine electric theory.
Bruce
S/V Allure
Compac 27

[kevin27]

It would be good see a picture of what you have. I think you are saying that you don't like the ground daisy chaining from the start battery. If that link is on the studs of a marine battery with nuts and lockwashers, it isn't going anywhere. The starter battery would have to melt to have any problem. That said, you could do a Y setup where the ground goes to a stud and separate negative cables go to each battery.

Blue Seas part 2001 would be good for a Y setup. 2105 would let you connect smaller ground wires as well while doing a Y. Multiple sources online will make up professional cables for you.

Isn't your boat the new custom build with factory mods? Would love to see pics of your engine bay and electrical panel.

[brackish]

Picture would be good.  In most cases (my 23 included) you are not grounding through battery one, you are simply jumping to the negative terminal.  The condition of the primary battery should not matter your ground circuit remains solid. Or maybe I don't understand what you are asking.

[moonlight]

As the resident ABYC Marine Electrician ...
All the batteries should have a common ground point.
All the loads should share this ground point.
I'd use a nice bus bar, and leave the starter/engine out of it.
A nice 600A bus bar, wired off to a smaller for house loads, would be more than ample for joining all the battery negatives, and going from that bus to the grounding lug on the engine.
DO NOT UNDERSIZE YOUR WIRE.  It's a common mistake.
USE ONLY TINNED COPPER CONNECTIONS.  Another common mistake.

In the power boat world, I shudder to reveal to you how much service work I perform, going behind somebody else, who used the "cheaper" guy to install his $5k, $7k, or $10k electronics package.  Cheap guy uses cheap components, works fine a year or two, then you can measure voltage everywhere but draw amperage no where.  The connections are shot, the wire is probably crap, and they say "but I've got 12V but it won't turn on"... yep, a dim bulb in the socket every time.  Spend the money for the good stuff, and don't look back and have to correct it later.

[kevin27]

Do you use regular tinned lugs or heavy power lugs? I've never seen a heavy power lug used but they are much nicer. And I've seen lots of bare copper lugs that were put there by the builder. (unfortunately)

[moonlight]

Tinned lugs.
Tinned bus bars (rated for amperage.  600A on the starting circuit more than sufficient)
Tinned wire

Too many manufacturers and boat builders skimp on tinned components.
But I'm not complaining.  Cheap electrical work by others keeps my kids fed, clothed, and in braces.

[wes]

Kevin - you're right, the heavy duty pugs are much nicer and are recommended over the regular flared lugs. Are you familiar with RC Collins' blog, marinehowto.com? Formerly Compass Marine. Highly recommended for his authoritative posts on marine electrics. He has an excellent illustrated post on proper crimping of battery cables and specifically on flared vs. heavy duty lugs.

Wes

[kevin27]

Yes, his site is amazing, he should write a book. I've actually seen a power lug on a boat, not even for 0000 cable, just regular flared.

[wes]

I've re-done all my battery and charger cables using 6 ga. marine wire and power lugs. It was a little challenging finding the power lugs in that size (or any size) but I ended up using the on-line ource he recommends. I also bit the bullet and bought the $200 crimper; yikes. But as RC says, "tools are free if you do the work yourself." Ha, I've used that argument with my wife many times now .

Wes