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Grounding batteries to engine block


hawaiianstyln

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I noticed the single battery setup that came with the boat, the battery was grounded to an extended bolt that comes off the block connecting or holding down one of the arms that you would use to pull the engine (whatever that's called).  Considering I have added batteries, I now have a four blue top optima and one red top optima setup.  I'm done installing\mounting the batteries and now running the wires.  I need to ground these batteries and wasn't sure where else I can ground them on the engine block since the current location doesn't have enough thread left.  The red top is using the ground from the original MFG location, but I need to ground these blue top optimas.  All 4 optimas are wired in parallel separate from the red starting battery.  Do I need to ground each optima to the engine or since they are running in parallel I only need to ground coming off one of them since they are basically setup as 1 bank?

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In a typical factory setup there is a single ground wire run from the observers compartment to the block.  No need to run separate wires, just make sure the 1 wire is big enough for the full drain of all the batteries you have added.    I like to use 00 (2/0) fine wire welding cable for battery cables.  Plenty big and the fine wire stuff is a lot more flexible than the typical cheap battery cable. 

Edited by oldjeep
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Just now, oldjeep said:

It's not the volts that gets you, its the amps ;)

correct and since each optima is 55 amps I also made sure my blue sea 3 position switch can handle (and it can easily).

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1 hour ago, hawaiianstyln said:

correct and since each optima is 55 amps I also made sure my blue sea 3 position switch can handle (and it can easily).

You do not need to route the house bank ground to anywhere other then the existing main engine ground cable on the cranking battery. 

That 55A is not a spec for choosing cable gauge or switch capacity. Thats an amp/hour spec for how long the battery will supply a load, before dropping down to its minimum voltage level. 

Your switch, cabling and any circuit protection need to be able to handle the draw that placed ON the battery. Stereo amps, lights, ballast pumps, etc. 

  • Like 2
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got it thanks @MLA!  I'm assuming I'm already good then because all we well before with the same system.  I haven't added any components, just batteries

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You should have a single ground lug at the block, then every other ground should be on a ground distribution block (common ground block).  Basically, run the ground from the block to the distribution block.  All batteries should be individually grounded to that distribution block, along with each amp, source unit, boat, etc.

I have 0.0 noise doing this setup and zero electrical issues.  That includes running, not running, Bluetooth, etc.  Only time I ever get even the slightest noise is when the boat is being charged with the on board charger at low volume.  Fixable, maybe...but why would I care?

  • Like 1
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Good to know about noise!  I have a slight tinge of ground noise but you would have to hokd your ear up to towers to hear the noise.  Either way it bothers me so i will make sure i follow this and also i know i have a ground loop as i didnt ground my Bluetooth back to same common ground as stereo amps,etc.....

thats my next project cleanup/fix

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On ‎1‎/‎11‎/‎2019 at 9:30 PM, Nitrousbird said:

You should have a single ground lug at the block, then every other ground should be on a ground distribution block (common ground block).  Basically, run the ground from the block to the distribution block.  All batteries should be individually grounded to that distribution block, along with each amp, source unit, boat, etc.

I have 0.0 noise doing this setup and zero electrical issues.  That includes running, not running, Bluetooth, etc.  Only time I ever get even the slightest noise is when the boat is being charged with the on board charger at low volume.  Fixable, maybe...but why would I care?

 

I guess I thought for all Audio components they had to actually go to a battery NEG terminal in a boat.  Your way suggests bypassing batteries and right to the block (well distribution block that is connected to the block).  Good to know you have zero noise.  I always follow the rule that all grounds from audio components need to go back to the SAME ground.  I always wondered if it "had" to be to a negative battery terminal or could it be right to the block.  I was going to buy a copper bar and make my own distribution point

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So you have 4 batteries making up the house bank. Unless these are scattered through the boat, it is a waste of cable and a bunch of extra terminations, to run each of their grounds to a ground BUS. Doing this, is treating the ground side WAY different them positive. What would you do that? 2nd, dont use copper in a boat, it will look like a Chia Pet in a few months. 

I would suggest a stainless marine BUS if you have excessive terminals on the battery terminals and need to relocate some. 

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10 minutes ago, MLA said:

So you have 4 batteries making up the house bank. Unless these are scattered through the boat, it is a waste of cable and a bunch of extra terminations, to run each of their grounds to a ground BUS. Doing this, is treating the ground side WAY different them positive. What would you do that? 2nd, dont use copper in a boat, it will look like a Chia Pet in a few months. 

I would suggest a stainless marine BUS if you have excessive terminals on the battery terminals and need to relocate some. 

I used copper.  Malibu used copper.  My 2012 ran connections and Malibu's 2001 connections all still look good.  I did not use copper clad aluminum on anything in the boat. 

One assumes the battery grounds are near the ground bus.  You can also tie the grounds together prior to going back to the bus bar.

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2 minutes ago, MLA said:

Then whats the BUS for? 

For all the ground connections.  I'd hate to try to have all the various grounds in my boat being tied directly to the battery - what a mess.

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Im a little confused. Per your post, you can bring all the grounds together prior to the BUS. OK, so whats the BUS doing, if all the grounds are already tied together, as you stated. Your last post echos my earlier post. A BUS is good for excessive grounds. Cables linking multiple batteries in a bank together, are not grounds. Only the last cable connecting the bank to the boat's ground, is the ground. But running individual battery grounds from the same bank, to it, is not ideal unless the batteries are spread out and a common BUS is the closest point. 

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