thunderbird1
New Member
How does the standard Mercathode system work? Does the system run only when the battery switch is on? On my boat it is protected by a 20 amp breaker, suggesting that it sucks lots of power?
Mysterious Mercathode System
- Thread starter thunderbird1
- Start date
thunderbird1
New Member
The link implies that the Mercathode system varies it's power consumption based on the amount of energy in the water. For those of you in the know, does this sound correct? The link also says the Mercathode system should be connected directly to the battery, which I do not believe is the case on my boat. I'll investigate further this weekend.
I had the dealer install the Mercathode II system on my boat and it supplements the one already installed. (see the third item down on this site http://www.psepmarineparts.biz/store/mercruiser_mercathode.htm) With that system, there are two "nodules" installed on the transom on either side of the out drive. Without these, experience has shown (at least in our Marina) that even if the standard Mercathode is working properly, you will still get corosion on a Bravo III drive. The Mercathode II apparently solves that problem. I witnessed corrosion first hand on two boats that didn't have that system. They had a 5 month old 260DA in their service bay that had paint bubbling on the drive and corrosion already started on the edges of the skeg. I also saw the same thing on a 250SLX that is wetslipped that was out of the water for cleaning and detailing. :smt021
Hey Dave I think I would be checking out a new place for my slipped boat it they have that much stray juice in the water :smt017
thunderbird1 said:
From what I read it does alter the current it puts into the water depending on what the sensor sees. I have read it might put out 20 to 40 mA in fresh water, and maybe 200 mA in salt water.
If you are connected to shore power, and your galvanic isolator is not blocking any shore power DC, then it would try and protect against that also, as I understand it.
Did you get a chance to see if yours is powered directly from the battery?
This thread belongs in the electrical section.
- Oct 4, 2006
- 2,344
- Boat Info
- 2006 300DA Sundancer
- Engines
- 350 Mags / Bravo III
The Mercathode system is less effective if you are slipped in water that has current (ie moving water). The moving water pulls the electrons away from the protected area....make certain you are using the correct annode for your water type.
You may want to go to www.mercurymarine.com and ask for their publication 90-881813 01 it is titled Marine Corrosion Protection Guide. It will teach you everything you want to know about how the system works and more important how to check that it IS working while the boat is in the water.
You may want to go to www.mercurymarine.com and ask for their publication 90-881813 01 it is titled Marine Corrosion Protection Guide. It will teach you everything you want to know about how the system works and more important how to check that it IS working while the boat is in the water.
Take a look at this as well http://www.sterndrives.com/bulletins/corrosion_protection.html
thunderbird1
New Member
Thanks for the document references Stray Cat and Dave S. !
- Oct 4, 2006
- 2,344
- Boat Info
- 2006 300DA Sundancer
- Engines
- 350 Mags / Bravo III
Your welcome, it makes very good toilet reading :thumbsup:
thunderbird1
New Member
One more question. Under what conditions might the Mercathode system (particularly the beefed-up Dave S. solution) cause corrosion?
- Oct 4, 2006
- 2,344
- Boat Info
- 2006 300DA Sundancer
- Engines
- 350 Mags / Bravo III
Tbird - Mercathode will not cause corrosion. As mentioned, if you have water movement consistantly passing by your drive (current), the Mercathode system will be less effective. For that same reason the protection of your sacrificial annodes will be slightly reduced also.
If the reference annode(s) should become caked with barnnacles etc. the Mercathode system is not effective at all. I use a soft nylon bristle brush (tooth brush would work) and give the reference annode a little attention while the boat is afloat during the season. This is done when I'm anchored.
If the Mercathode controller fails, mine did on my 270 and I didn't know it until I pulled the boat in the fall, all you have for protection then is the annodes.
If the reference annode(s) should become caked with barnnacles etc. the Mercathode system is not effective at all. I use a soft nylon bristle brush (tooth brush would work) and give the reference annode a little attention while the boat is afloat during the season. This is done when I'm anchored.
If the Mercathode controller fails, mine did on my 270 and I didn't know it until I pulled the boat in the fall, all you have for protection then is the annodes.
asimpkinsjr
New Member
thunderbird1 said:
Merthacode works this way according to the manuals and to the Sea Ray rep...because I had some concerns about electrolysis issues...
for the mercathode to work the battery must be in the "Both" position. The way Sea Ray installs the mercathode if the battery is in the 1 or 2 position the system does not work, only in the both...the right way to install would have been wire it right into the harness.
asimpkinsjr said:
Oh great...............I have always turned off my battery switch when I leave the boat. :smt021
There is nothing in the 260DA owners manual (in the Mercathode section) that tells you to leave the battery switched turned on or in the both postion. But a cursory look at the wiring diagram in the manual suggests you are right. I am headed to my dealer today to get this straightened out. How could Sea Ray let such an important thing like this fall thru the cracks??? :smt013
OK........here's a short update on what I learned so far. I was able to talk to a Tech on this matter today. He assured me the Mercathode System is hardwired to one of the batteries so it makes no difference if the battery switch is off or on. He says they double check this on all new boats and he told me how to check mine. The purple wire going to the mercathode block (mines mounted on the engine itself) is the hot wire. With the battery switch turned off, use a multi meter or a test light between that wire and ground ( use the engine block itself for the ground). If it's hot with the switch turned off, then you know you are directly wired to the battery. I plan to test mine this weekend and will report back once I have done so.
Dave S said:
Dave........thanks for the information. I am not real adept at reading wiring diagrams but esssentially what you reported is how the tech explained it to me. I really do appreciate you clarifying this for me also.
I guess one of the things that makes me mad about situations like this is what is not said in the owners manual. Namely if you read the section of the owners manual that talks about functions not affected when you turn off the battery switch, the Mercathode system is not mentioned at all. They do mention things like the bilge pumps, sump pumps, blower, stereo memory, systems monitor and battery charger input. So why isn't Mercathode mentioned? :smt017
And to top this off when you read the section on the Mercathode iteself, nothing is mentioned there either. I find no reasonable expalnation for any of this and hopefully Sea Ray will fix their future manuals.
At least we have folks like you around that can clarify things and that's what makes this board so great. Again............thanks Dave.
I guess one of the things that makes me mad about situations like this is what is not said in the owners manual. Namely if you read the section of the owners manual that talks about functions not affected when you turn off the battery switch, the Mercathode system is not mentioned at all. They do mention things like the bilge pumps, sump pumps, blower, stereo memory, systems monitor and battery charger input. So why isn't Mercathode mentioned? :smt017
And to top this off when you read the section on the Mercathode iteself, nothing is mentioned there either. I find no reasonable expalnation for any of this and hopefully Sea Ray will fix their future manuals.
At least we have folks like you around that can clarify things and that's what makes this board so great. Again............thanks Dave.
asimpkinsjr
New Member
Dave S said:
trust me, keep leaving it off and you will be able to tell when you inspect your zincs...my boat was burning through them the year I bought it....chewed them to bits in 2 months...spent a week looking through the boat and the Merc Mercathode manuals...and viola!
asimpkinsjr
New Member
Dave S said:
Dave, unless the wiring on your boat is dramatically different from the 05 he is wrong...that assumption is logical but hardly correct....put a voltimeter on the mercathode unit on the lower with the battery switch moved to off...you will see a gradual drop in the voltage as the capacitors somewhere in the system slowly discharge...or better yet look at the battery wiring harness, you wont find the mercathode wiring...simpler yet, look at Mercurys mercathode install paperwork which incidentally is seperate from the owners manuals...Ill see if I can dig up the paperwork sea ray drummed up for me on this early this season
Dave S, here is a copy of a part of the diagram for the 260 DA. It clearly shows the Mercathode unit wired to the same bus as the bilge pumps and other things on that bus.
For my boat, I have never found a Sea Ray wiring diagram, so you are at least ahead of me there, and Sea Ray is getting better at making the information available. I have not seen the wiring diagrams you have in actual hard copy, but I would think they are so small as to be very hard to read.
Here is a blown up copy of the batteries, selector switch, and the first circuit breakers only. It should be large enough you can see it. Also here is a 1200% blow up view of the selector switch so you can see it. These small images are links to the real ones. I hope these are legal to post!
Note that the selector switch diagram does not include the contacts that open and close between the terminal labelled FEEDER and the BAT 1 and BAT 2 terminals. You have to just know these contacts exist, and that the Feeder terminal is internally connected to neither Bat 1 or Bat 2 (OFF), either Bat 1 or Bat 2 (1 or 2), or to both (BOTH) according the the position of the switch.
This shows how Sea Ray states your boat should be wired. Seems there is some debate as to the real wiring. My boat is wired essentially like this diagram.
For my boat, I have never found a Sea Ray wiring diagram, so you are at least ahead of me there, and Sea Ray is getting better at making the information available. I have not seen the wiring diagrams you have in actual hard copy, but I would think they are so small as to be very hard to read.
Here is a blown up copy of the batteries, selector switch, and the first circuit breakers only. It should be large enough you can see it. Also here is a 1200% blow up view of the selector switch so you can see it. These small images are links to the real ones. I hope these are legal to post!
Note that the selector switch diagram does not include the contacts that open and close between the terminal labelled FEEDER and the BAT 1 and BAT 2 terminals. You have to just know these contacts exist, and that the Feeder terminal is internally connected to neither Bat 1 or Bat 2 (OFF), either Bat 1 or Bat 2 (1 or 2), or to both (BOTH) according the the position of the switch.
This shows how Sea Ray states your boat should be wired. Seems there is some debate as to the real wiring. My boat is wired essentially like this diagram.
