Friday, December 4, 2020

Re: [electricboats] Grounding.

Hi, Ryan and Bob and everyone,

I've been lurking and learning, putting down a foundation of knowledge for when I finally swap the ICE for electric. I'm feeling more knowledgeable all the time. 

Though I've not done the swap yet and won't for a while, I have a question about grounding that might apply to juicers too. Volvo-Penta recalled my engine (EPA recall) and put in a brand new one at their expense, a gift I couldn't turn down, but the propeller shaft isn't hooked up yet. The coupler is two disks connected with tough rubber grommets reminiscent of small engine mounts. That of course electrically isolates the propeller shaft from the engine. The flat copper bonding and its connection to the cutlass bearing looks a little iffy to me.

So: Thinking that a big wire is better than a small wire to the shaft, I crossed the two disks with two wires about 1/0 gauge with swaged terminals (the wires cross at 90 degrees to neutralize balance issues in the coupling). The engine will still be part of the circuit to the battery negative terminal, but the additional ground will be a definitive connection to the sea. Is this bad? Will it accelerate corrosion of the propeller, all other things being equal (like good zincs). Or will it provide additional protection, so long as I contain corrosion, e.g.,, by enhancing lightning strikes' travel to earth?

Am I hereby confessing my utter incompetence in this matter? :~))

Thanks! I appreciate all the great education here!

Best regards,

Dan
San Diego, CA
32' Cheoy Lee

Act always as if the future of the universe depends on what you do, while laughing at yourself for thinking that anything you do makes any difference.

                                                                                                  A Buddhist saying


On Fri, Dec 4, 2020 at 9:28 AM Bob Jennings <heatnh@gmail.com> wrote:
Dan,

William had asked where to ground to now that his ICE was history. If you follow AYBC wiring guidelines it's pretty clear the AC ground & DC negative connect to the same buss/ground.  There are a couple of EP vendors that recommend this also.

I have two free floating DC systems on my boat. However my solar case ground connects to the same keel bolt that the AC & inverter case ground connects to  along with the lightning bond. I figure once the solar case was grounded my DC system became defacto grounded depending on which battery bank was being charged. I have considered grounding my drop pan that the electric drive is bolted to more for lightning strike protection than anything else.  Is this right approach? I don't know.  I'm sure a surveyor would have a field day with most of our electric boat wiring systems.

I read somewhere there's supposed to be some new ABYC guidelines coming out soon specifically for electric boats.  It'll be interesting to see what they recommend.

On Fri, Dec 4, 2020, 10:35 AM Daniel Michaels via groups.io <nov32394=yahoo.com@groups.io> wrote:
Bob Why would you do this for DC? You would do that for a lightning rod termination. DC does not need a ground to earth. AC needs a ground to earth. The reason you ground to the engine is because it is a massive block of metal. Completes the loop. Ground from battery to block, ground from anything else to block or battery it does not matter.

Dan

On Thursday, December 3, 2020, 06:51:17 PM MST, Bob Jennings <heatnh@gmail.com> wrote:


Ground to a keel bolt if one is available.

On Thu, Dec 3, 2020, 6:36 PM William Shannahan via groups.io <shannahanwilliam=yahoo.com@groups.io> wrote:
So I removed the old diesel and am getting ready to install the electric motor. Was reviewing Don Casey's book and came across the illustration showing the whole DC System being grounded to the diesel engine block.
Since that is no longer there what should I ground to? 

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