How To: Marine Electrical Seminar - Galvanic Isolator Troubleshooting - Ep 30/30

Join Jeff Cote from Pacific Yacht Systems as he presents an in-depth seminar on understanding, installing and troubleshooting marine electrical systems. Episode 16 touches on the pros and cons of a galvanic isolator to protect against stray current.
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Jeff Cote is a systems design expert and owner of Pacific Yacht Systems, a full service shop delivering marine electrical and navigation solutions for recreational boats. Visit the PYS website and blog for info and articles on marine electrical systems, projects and testimonials.
Website: www.pysystems.ca
Facebook: / pacificyachtsystems
Instagram: / pacificyachtsystems
Twitter: / pysystems

[@DollarTreeFlyer]

Sad to see this series come to an end, thanks Jeff I learned a tremendous amount from you!

[@PacificYachtSystems]

Hi John, thanks! How nice of you. Glad you to know you stuck right to the end.

[@abady4ever283]

I watch all 30 videos and I loved it Thank you Jeff

[@PacificYachtSystems]

Thanks Abady 4 Ever!

[@pete9501]

European yachts are often neutral earth bonded, mine is from the original manufacturer. Also worth noting that other than the P bracket and rudder shaft no through hulls are bonded. Not wrong just a different approach the US systems and worth mentioning.

[@Hoganoutdoors]

Love your content! Simplest stray current solution? Don't plug-in to the grid. I'm currently installing a 1kw solar system on my boat along with a 200 ah LiFePo battery bank to supplement my 276 ah AGM bank. Banks will be isolated by a switch and have separate charging sources, with the AGMs serving as a starting bank and as a back-up house bank. Boat will be inverter based. So far the AGM bank is serving my needs well with careful energy use management, even though only 1/2 of the solar array is installed, and it's been very cloudy / foggy. If a boat is used infrequently or rarely, just install a solar panel with enough output to float charge your batteries and disconnect from shore power. Much safer than even a galvanic isolator. Shore power cords are notorious sources of fires - I've burned up two over the years due to hidden corrosion INSIDE the wires or due to a loose / poor connection at the inlet. Boats move constantly, so no matter how well you think you've secured that AC feed, there's always a risk of it working loose and arcing, heating up, and melting. Circuit breakers will not trip in this situation. When actually using the boat your alternator should keep the batteries charged, assuming it's sized and regulated properly. If you primarily sail and your batteries are deeply discharged after a week of cruising and anchoring, either run the engine, install a bigger solar system, or plug into shore power overnight when you return to the marina. If your charger can't top up a bank depleted to 50% within 6 or 7 hours or so, it's too small, and you're murdering your batteries with it anyway. Get a charger capable of putting out .2C (20 amps for a 100 amp hour battery bank) and you'll be able to top everything up in 3 or 4 hours depending on battery chemistry. A big solar system and lithium battery bank isn't a cheap solution - I live aboard and and am preparing the boat for cruising, so the excess generation and storage capacity and redundancy are critical in my opinion, but it's nice to know that I won't need an isolation transformer or galvanic isolater to protect my prop or keel bolts if I leave the boat in a marina for an extended period. Second simplest solution: Have a diver clean your bottom and inspect your zincs monthly. If you're burning up zincs more than once every year or two, you've got a stray current problem in the marina - either unplug from shore power, install a galvanic isolator, and/or stay on top of those zincs!

[@koffibanan3099]

All very interesting stuff. I agree about the landbased electricians, I myself thought I knew everything, but before making all these mistakes I luckily decided to do some research. Turned out to be quite the rabbit hole :) Couple of things I was wondering while watching this: - reverse polarity + neutral to earth bond, wouldn't that trip the breaker, since current is now flowing through the neutral wire, down to the earth wire, back to shore -> short circuit? Only when the earth wire is compromised (for instance a failed-open galvanic isolator), would this happen and create a lethal situation? - In European boats the DC- and AC ground are rarely bonded, presumably to help prevent stray DC corrosion. A RCD (GFCI) of 30mA is installed though and would provide protection in all (?) scenarios. I have read a ton about this, but am still undecided whether to bond DC and AC grounds together. The debate seems to end in the question of whether or not you're willing to trust an electronic device such as an RCD. The AC-DC bond would provide additional protection if the RCD were to fail. Again thank you very much for the info you put out!!

[@HelderNevesHelderNeves]

If you have an AC battery charger, then the AC ground is automatically connected to your DC ground, right?

[@koffibanan3099]

@@HelderNevesHelderNeves Hmm! I'm not really sure about that, the charger is probably grounded to the AC, but the DC charging voltage could (and probably is) floating vs the AC supply. I'll check this next time I'm on the boat!

[@LucScheffers]

Thanks, I watched your series with interest since I am doing a boat refit, and planning the new electrics as a newbe as well and learning a lot. I get the transformer part but I don't understand the galvanic corrosion thingy as a total corrosion block. To my understanding in a GI are two opposing diodes and the blocking is based on a certain hight of the voltage and not current. And the voltage drop which a diode in line causes. That seems to be just 1,2 volt. Any stray current better said, stray voltage higher than 1,2 volt is still passing through. fLet say from 1,6 volts and some miliamps, 0,4 volts and the same milliamps are still passing, enough to cause corrosion. Is this a correct thought or do I mis something?

[@carloscoello503]

Any special considerations for an aluminum catamaran? Thanks

[@j_j_h221]

If I have two shore power hookups can I put 1 isolator before the panel that is tied to both shore inlets?

[@PacificYachtSystems]

If the galvanic islaotor is rated high enough yes. IE a 60a galvanic isloator on two 30a shore cords. Or if only one is used at a time (ie port / stb shore transfer switch) then a single 30a could do both

[@torstenhansen4308]

Victron makes isolation transformers that weigh around 50 pounds and cost less than $700. Any reason you wouldn’t use one of those?

[@PacificYachtSystems]

Thanks Mike for the feedback, much appreciated.

[@HelderNevesHelderNeves]

What if your AC and DC are not connected? Is there still the "galvanic issue"?

[@PacificYachtSystems]

Hi Helder, nope, but disconnecting your AC to DC bond is like not wearing a seatbelt because of chafe.

[@HelderNevesHelderNeves]

@@PacificYachtSystems Love your answer :) The story behind is: - the previous owner told us to turn of "this switch" when we are not on the boat. I always did until I bothered to investigate. "This switch" disconnects the DC ground! Why? Maybe this way there will never be galvanic issues, I am thinking now. When charging the battery with land power, the battery will be just grounded to land. Seems to work but after watching your videos it looks like I must use that switch on the red wire instead, and just get a Galvanic isolator right?

[@apackwestbound5946]

May I suggest that if you are going to record question and answer sessions to be broadcasted again and you are not going to provide a microphone for each person whom you call on with a question, then repeat the question so those watching online, or listening over some other media, understand what the question is that is being answered. Most of the time the question is simple to deduct by listening to the answer but not always.

[@noelreuland8311]

It would help if the questions were repeated so the viewer could know what you are answering

[@PacificYachtSystems]

Good point Noel, learnt this the hard ware, and now i know better.