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Re: Wifi extenders and the bonding system

CW Bill Rouse
 

Scott,

I hope you guys are safe and healthy.

Since I am a simple person who enjoys simple explanations, let me jump in with what I think will help you. 

The Amel Bonding Checking System on your Amel 54 looks for a connection between the Amel Bonding System and either a positive or a negative connection to the 24-volt battery bank.

Because the A-54, connects many additional things to the Bonding System than previous models, you have a greater chance of some sort of bridge (connection) between things physically mounted on the life rail, lifeline, masts, or anything connected to these things. Boats prior to the 54 did not have all of these additional Bonding System connections. And remember, it could be something the previous owner or his hired technician did. If the Amel Bonding System is compromised by a "wrong" installation somewhere on the boat, 100% of the bonding system is likewise somewhat compromised.

So, when you physically mount a device on the mast or any of the above-interconnected devices, if that device has an internal electrical circuit (+ or -) connected to the case, by mounting it, you have connected 24-volt battery bank voltage to the Amel Bonding System. To further confuse both of us, the Amel Bonding System is almost universally misunderstood by nearly 100% of people you may hire to work on your boat. Something wired or connected wrong by these good-intentioned folks can totally incapacitate the benefit that the Amel Bonding System brings to you.

On another related matter, it seems that nearly all engine repowers that I have recently inspected were done without 12-volt negative isolation. Of course, the C-Drive will likely suffer a long-term death when 12-volt isolation is ignored. I am guessing 4-6 years and poof!

Bill 
CW Bill Rouse Amel Owners Yacht School
Address: 720 Winnie, Galveston Island, Texas 77550 
View My Training Calendar


On Mon, Aug 17, 2020 at 2:07 PM Scott SV Tengah <Scott.nguyen@...> wrote:
Hi all,

This is really a question about bonding, which I'm very weak on. 

We have been using a Wirie Pro wifi extender on our A54 for over 2 years and while the Wirie didn't work that great, I separately used the Ubiquiti Bullet M2HP titanium which was part of the package and that worked great. It was mounted on a plastic Pelican case and therefore electrically isolated.

Recently, it died and I needed a replacement but the Bullet M2hp-Ti is no longer being made. I went for an Alfa Tube 2HP, which is generally quite similar.
https://store.rokland.com/products/alfa-tube-2hp-802-11n-long-distance-outdoor-wi-fi-poe-ap-cpe-ip68

The problem with all these devices is that the antenna port is typically connected internally to device power. So when you mount the device on a rail or on the masthead, it sends voltage to the exterior metal and hence the Amel bonding system. The old Bullet was mounted by Wirie Pro in a plastic Pelican case, but I am almost certain the Bullet's antenna port was connected to power also. The Alfa's design doesn't make it easy to mount on the same Pelican case.
 
Since our A54 is 24v,  I had to use a DC-DC up-converter to get 48v which is then fed into a Passive PoE Injector for my Alfa. The PoE injector is just a simple device that adds power to some of the wire pairs in the the ethernet cable - that is how the device gets power. Once I plugged in the powered ethernet cable into the masthead mounted Alfa, the tester light on our Amel for BOTH + and -  lit up and using a multimeter I saw voltage in our rigging. That is obviously not good.

A few questions:

1) Is the fact that the Alfa runs on 48v and the rest of the boat is at 24v the reason why the Amel tester lights up? If this is the case, I can buy another wifi extender that will run on 24v. That doesn't seem likely as the 24v device's antenna connector would still be energized, but I figured I'd ask.

2) The other option to run the Alfa is a 220vAC power brick run on inverter which then provides 48vDC to the Alfa. Very ineffiecient but in this case, the Amel tester light does NOT light up, probably because the power brick isolates the 48v being provided from the boat's 24v battery circuit? But I presume the rigging is still being energized with 48v? But without a way for the power to complete the circuit through the rigging and get back to the source of the 48vdc (power brick), is this not a problem with respect to corrosion?

I hope my question is explained well enough because my understanding of bonding is quite thin. Many boaters use these wifi extenders and no one has talked about this issue but then again, most of them don't deal with our floating ground bonding system.
 
 
--
Scott 
2007 A54 #69
SV Tengah
http://www.svtengah.com

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