Do I need a Galvanic Isolator?

L

Living the dream

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C Dory Year
2007
C Dory Model
255 Tomcat
Hull Identification Number
CD025550G607
Vessel Name
Kit Kat
I currently have a Guest 30 AMP galvanic isolator model 2433 with Guest 20 AMP 5/5/10 charger. I'm updating the electric system and plan on replacing the charger with a Victron Smart IP 122 30 AMP 3 output. I'm moving the house batteries to the port seat compartment.
My question is- Do I need to retain the Galvanic Isolator? My concern is that I will be on a generator most of the time. Will the Smart charger take care of that? Does it make a difference if my outboards are in/out of the water during charging?

Thanks, Bob
 
Bob,
“Today the ABYC standards require the use of Fail Safe galvanic isolators such as the ProMariner ProSafe FS30 or the ProMariner ProSafe FS60. The designation FS or fail safe means that these devices fail closed instead of open as a normal diode would. By failing closed you only lose galvanic protection but not your SAFETY GROUND to shore.”

If your Guest GI has a red LED lit it has failed. I replaced mine with the ProSafe FS30.

When you are connected to shore power at a marina with other boats, a Galvanic Isolator helps protect your boat’s anodes and underwater metals from being eaten away by other boats with big bronze props. The electrical connection is via the marina power pedestal to other boats.

My Yamahas have a large bucket handle shape anode which remains submerged even when the engine is tilted out of the water. I suspect most if not all do. Down here we tilt them up to minimize marine growth, not for galvanic corrosion avoidance.

The non-smart (non three stage) engine alternators alone can’t fully charge the batteries past 80% or so, but the smart chargers can when they are powered by the generator or shore power. Portable generators may have a 12v battery charger output, but it too is likely unregulated.

You'll need AGM batteries if you want to charge them inside the boat. Lithium is another subject.

At least, that’s my understanding and I welcome corrections.

Hope this is helpful. Cheers from Fort Myers beach!

John
 
John,
I do not see a red light on my Guest galvanic isolator not sure if it's even working. I understand you can test them but it's an old piece of equipment. I think I will just up date to a new fail safe isolator, might as well do it right the first time. I will be using AGM batteries with a generator most of the time. Thanks for the reply.

Bob
 
Living the dream":15ux0wl6 said:
John,
I do not see a red light on my Guest galvanic isolator not sure if it's even working. I understand you can test them but it's an old piece of equipment. I think I will just up date to a new fail safe isolator, might as well do it right the first time. I will be using AGM batteries with a generator most of the time. Thanks for the reply.

Bob
Click to expand...

Maybe this will help

test_galvanic_isolator.png
 
I assume you know the the GI is only functioning when you are plugged into shore power (actually plugged into a land based system). It doesn't come into play when you are on your generator.
 
Okay I'm trying to get my head wrapped around this.
On the issue of the galvanic isolator, assuming it's working correctly then I don't think it makes any difference in either a generator scenario compared to using onshore power. If we are talking about hull grounding taking the place of earth I would think it may help to protect the occupants on the boat. Not sure of anybody outside of the boat. We will be using a generator most of the time, just want do it safely. I could be wrong but I'm definitely confused.

Thanks, Bob
 
Here's one small data point for you.....

A galvanic isolator is really nothing more than a large capacitor. It's only job is to allow AC current to flow through it, but at the same time not allow any DC current to flow. It isolates the boat from the shore so that no DC current can flow in either direction over the wire(s) that connects the boat to the shore.
 
“Galvanic isolators solve a common cause of corrosion by interrupting galvanic circuits with other boats and the dock when your boat is plugged into a shore power system. These isolators prevent stray DC corrosion-producing currents from passing through the AC green wire, all while maintaining AC ground safety and protecting against zinc loss. “

If you never, ever plug your boat into marina shore power, or when using your generator, you don’t need one. But when you sell your boat, the buyer’s surveyor will note it needs one, so you’ll pay
now or pay later. I’d replace it for under $300. It’s only three wires.

https://www.go2marine.com/Professional- ... 1&amps=153

Happy shopping! We’ll be back at the pool.

John
 
I'm going to replace with a ProSafe 30amp and be done with it. My nephew who is a licensed electrician and (likes to fish) will be helping with the project and will be checking my work.

Thanks for comments.
Bob
 
Hi,

Are there any easy galvanic isolator setups? Like something I can plug my shore power extension cord into, and then plug my battery charger into the GI? Everything I see looks like I have to splice an extension cord so the ground goes through the GI. Thanks.

- tom
 
Right, but I'd have to cut into an extension cord to get to the ground wire.
Click to expand...
So you don't have a shore power receptacle mounted on the boat that the shore power extension cord plugs into? Normally, the GI goes immediately downstream of that receptacle since the ground wire is already exposed (on its way to the AC panel).

Alternatively, I guess you are interested simply using an extension cord that dead ends in the cockpit of your boat. If so, I can see the advantage of what you are looking for. Perhaps the problem is that most of our boats are set up for 30 amps which means the GI has to be pretty big and heavy....too big to fit in an enlarged extension cord connector. Maybe the UK has them since the volts is 240v there and so not so many amps.
 
smckean (Tosca)":1lyz3q9v said:
So you don't have a shore power receptacle mounted on the boat that the shore power extension cord plugs into? Normally, the GI goes immediately downstream of that receptacle since the ground wire is already exposed (on its way to the AC panel).
Click to expand...

Nope, no shore power. I just have two devices on the boat that can take AC power, a Victron IP65 battery charger, and an Ecoflow Delta Mini "solar generator". The only time I plug into shore power is from a GFCI extension cord to those two devices at my marina. So I'm trying to figure out how I can add a GI with no AC panel or receptacle on board.
 
OOPS....I see I posted an edited version of my post just after your reply. Ships in the night......
 
smckean (Tosca)":2nm9qblz said:
Alternatively, I guess you are interested simply using an extension cord that dead ends in the cockpit of your boat. If so, I can see the advantage of what you are looking for. Perhaps the problem is that most of our boats are set up for 30 amps which means the GI has to be pretty big and heavy....too big to fit in an enlarged extension cord connector. Maybe the UK has them since the volts is 240v there and so not so many amps.
Click to expand...

I got this from that UK company I posted:

"I'm afraid that we don't do an isolator with NEMA connectors, as NEMAs aren't common over here, but you could easily remove the Euro connectors fitted and replace them with the NEMA types. The isolators are otherwise fine to use in the US, as they will work perfectly well with 110/120V supplies."

But maybe I don't need one according to Pacific Yacht Systems:

https://www.youtube.com/watch?v=JyMvhNmcZZU&t=35
 
NEMA is a 50 amp 240 plug used on high loads--electric dryer for example.

There is the NMEA-which is standard sentencing protocol. They use NMEA all over the World.

I have set up several boats using a shore power connector as used in Bass boats, which goes directly to the battery charger, and maybe one outlet. This takes the female end of an extension cord. No galvanic isolator.
 
thataway":mnuaq5f6 said:
NEMA is a 50 amp 240 plug used on high loads--electric dryer for example.

There is the NMEA-which is standard sentencing protocol. They use NMEA all over the World.

I have set up several boats using a shore power connector as used in Bass boats, which goes directly to the battery charger, and maybe one outlet. This takes the female end of an extension cord. No galvanic isolator.
Click to expand...

Hi Bob,

I should have said NEMA 5-15P and NEMA 5-15R, common extension cord plugs.

For some reason I was hung up on a battery charger constantly plugged in, used like a battery tender, would I need a GI for that, for a boat that is stored on the water. But looks like the answer is no.

Thanks all!

- tom
 
....battery charger constantly plugged in, used like a battery tender, would I need a GI for that, for a boat that is stored on the water. But looks like the answer is no.
Click to expand...
Just be sure that you don't ground the battery charger case/etc to the engine or to any other metal that touches the water.
 
smckean (Tosca)":1x98df2p said:
Just be sure that you don't ground the battery charger case/etc to the engine or to any other metal that touches the water.
Click to expand...

I am fully over my skis now.

shore power -> Victron IP65 charger -> onboard batteries (which are connected to my outboard)

Does my battery charger convert AC ground into the DC neg connected to my battery?

Thanks all.
 
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