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Old 19-06-2019, 16:47   #1
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Beta 14 eating anodes at a blistering rate

So my Beta 14 has probably always gone through anodes rather quickly - every few months or so - but lately it seems like it has gotten worse. I just checked my log, and I've replaced the pencil anode 3 times in 3 months. Those times the anode was either intact and crumbled down to 50% after I pulled it, or already down to 50% or less. I would much rather replace the anode prematurely for the obvious reasons, but also because the zinc oxide clogs the heat exchanger, and the engine will eventually start overheating. I've had to clean the heat exchanger twice in two years as a result.

From my research, a zinc wasting this quickly is usually the result of stray current or a floating ground. The boat is in the tropics, but is never in a marina, nor is it close to any possible source of stray current. Plus, it's been in 3 very different anchorages and two entirely different oceans in those 3 months.

Then the next suspect would be something shorting to the negative terminal on the engine?

A few extra notes. The propeller shaft is electrically isolated from the engine. I recently began hanging an anode overboard, connected to the negative bus, but I don't see any obvious signs of corrosion on that anode, nor do I see any reduction of the rate of wasting in the pencil anode.
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Old 19-06-2019, 18:21   #2
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Re: Beta 14 eating anodes at a blistering rate

Something is wired wrong. Pos + neg reversed on some electronic item, maybe if you're making AC power, could be a AC ground problem. Could be a cheap inverter or maybe a bad power supply for LED lights.

My generators, 3 & 4 cylinder diesels, zincs, easily go 5 years and still look serviceable.

With a good meter, you can look for small power draws, and gradually disconnect items.



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Old 19-06-2019, 18:40   #3
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Beta 14 eating anodes at a blistering rate

Iím thinking alternator, mostly because the hanging zinc isnít being eaten up, and I bet itís not in the water when heís motoring, so Iím theorizing that the stray current is only there during engine operation.

Can bad diodes allow dc current back into the alternator and therefore the engine block?
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Old 19-06-2019, 18:45   #4
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Re: Beta 14 eating anodes at a blistering rate

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Iím thinking alternator, mostly because the hanging zinc isnít being eaten up, and I bet itís not in the water when heís motoring.

Can bad diodes allow dc current back into the alternator and therefore the engine block?
This is correct, I bring it aboard when I'm motoring, unless I forget.

The engine has seen much more use in the last few months as compared to other months owing to being in the ITCZ and a few other factors. I mean motoring, not charging at anchor.

Regarding an improperly wired device, how should I perform this test, and how sensitive does my meter need to be?

I do have an inverter, but it only rarely sees use, and when it's not in use it's disconnected from the system entirely.

Regarding the alternator, is there any way for me to test if this is the case, and is there any precedent for this happening?

Thanks for the replies.
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Old 19-06-2019, 23:43   #5
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Re: Beta 14 eating anodes at a blistering rate

Usually if some diodes are bad, alternator output is effected. Usually alternator won't produce full output. To test overall, disconnect wiring to alternator, meter leads to the pos (main wire to battery) and the case. Then switch leads. You should have high resistance in one position and low resistance in the other.
Most autoparts stores will test the alternator for free.
My guess is the zincs are getting wasted from a constant small source. If it was my boat, I'd shut everything off, disconnect one cable from the battery and measure between the cable end and the battery post. See if there's voltage. If there is voltage, start disconnecting items (one at a time) from the system and then recheck for voltage as before. Keep removing items until the volts are zero.



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Old 20-06-2019, 03:32   #6
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Re: Beta 14 eating anodes at a blistering rate

I am not a fan of using engine blocks as buss bars. You might study where your alternator, starter and other equipment are grounded. If they are attached at different spots on the engine block you might consider moving them to one spot or a nearby buss bar. Give the current the most direct path back to its source versus winding its way through the engine.
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Old 20-06-2019, 04:25   #7
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Re: Beta 14 eating anodes at a blistering rate

You in a marina ?
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Old 20-06-2019, 06:15   #8
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Re: Beta 14 eating anodes at a blistering rate

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Originally Posted by Emmalina View Post
You in a marina ?
Quote:
Originally Posted by scuttlebooty View Post
......... The boat is in the tropics, but is never in a marina, nor is it close to any possible source of stray current. Plus, it's been in 3 very different anchorages and two entirely different oceans in those 3 months........
There you go, question answered in the OP - second paragraph
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Old 20-06-2019, 06:51   #9
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Re: Beta 14 eating anodes at a blistering rate

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Originally Posted by Lepke View Post
Usually if some diodes are bad, alternator output is effected. Usually alternator won't produce full output. To test overall, disconnect wiring to alternator, meter leads to the pos (main wire to battery) and the case. Then switch leads. You should have high resistance in one position and low resistance in the other.
Most autoparts stores will test the alternator for free.
My guess is the zincs are getting wasted from a constant small source. If it was my boat, I'd shut everything off, disconnect one cable from the battery and measure between the cable end and the battery post. See if there's voltage. If there is voltage, start disconnecting items (one at a time) from the system and then recheck for voltage as before. Keep removing items until the volts are zero.


Lepke gives excellent advice.
You do not have to be in a marina to suffer from stray current. In fact 99.9% of stray current damage is caused by ones own boat whether in a marina or not.
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Old 20-06-2019, 07:17   #10
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Re: Beta 14 eating anodes at a blistering rate

I believe a key issue is why isn't the hanging zinc doing its job?
Is it connected directly to the engine block? If it is, then it would appear that either the connection isn't good, or that your engine zinc is being wasted when the hanging zinc isn't in the water, which I assume is only when your motoring.
I'm under zinc'd with only a prop zinc for the whole boat, so therefore I hang a zinc, aluminum actually, but it does waste slowly, will likely last two years, is extremely easy to inspect of course.
Yours not wasting, but your engine ones are is pointing to some problem.

If your sure the connection is good, try leaving it in the water when you motor, if your engine zincs stop wasting, then you know your stray current is only present with the engine running.

Of course if you can get a hold of a half cell that should greatly help in locating the problem
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Old 20-06-2019, 10:02   #11
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Re: Beta 14 eating anodes at a blistering rate

OK, so let's review.

There's likely a short from the positive to negative, or perhaps from the alternator, and because the entire engine is a negative, this stray current is giving a source of electrons for a galvanic reaction to occur in the raw water loop, thus wasting the anode. Correct?

Both battery negatives (starter and house) do indeed meet at the engine block, and then a third negative goes from there to a negative bus for all the systems.

Quote:
Originally Posted by Lepke View Post
If it was my boat, I'd shut everything off, disconnect one cable from the battery and measure between the cable end and the battery post. See if there's voltage. If there is voltage, start disconnecting items (one at a time) from the system and then recheck for voltage as before. Keep removing items until the volts are zero.
To clarify, I'm looking for a potential across the battery negative terminal (disconnected) and the negative cable, is that correct?

I'll double check the connections on the hanging anode. It's just a prop shaft zinc hanging on a length of stainless steel wire that is hanging off the pushpit, which I have wired to the negative terminal on the shunt connected to the house bank. I've done connectivity test between the zinc and the engine block, but I'll check again.
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Old 20-06-2019, 10:09   #12
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Beta 14 eating anodes at a blistering rate

If the zinc is just hanging on the wire, itís likely that isnít a good enough connection, you need a solid connection, like a hole drilled, tapped and bolted type of thing, or buy a hanging zinc if possible.

If you can buy one, Iíd use aluminum as itís more protective, it seems if you have a mix of aluminum and zinc anodes, the aluminum will waste away first.
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Old 20-06-2019, 10:11   #13
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Re: Beta 14 eating anodes at a blistering rate

Quote:
Originally Posted by scuttlebooty View Post
OK, so let's review.

There's likely a short from the positive to negative, or perhaps from the alternator, and because the entire engine is a negative, this stray current is giving a source of electrons for a galvanic reaction to occur in the raw water loop, thus wasting the anode. Correct?

Both battery negatives (starter and house) do indeed meet at the engine block, and then a third negative goes from there to a negative bus for all the systems.



To clarify, I'm looking for a potential across the battery negative terminal (disconnected) and the negative cable, is that correct?

I'll double check the connections on the hanging anode. It's just a prop shaft zinc hanging on a length of stainless steel wire that is hanging off the pushpit, which I have wired to the negative terminal on the shunt connected to the house bank. I've done connectivity test between the zinc and the engine block, but I'll check again.
Your hanging anode may have a good connection but anodes do not have infinite reach, they must be close to the metal they are supposed to protect.
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Old 20-06-2019, 10:14   #14
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Re: Beta 14 eating anodes at a blistering rate

To clarify, I coiled the wire around the two bolts holding the two halves of the zinc together and tightened them down hard to help ensure a good connection. May or may not have been sufficient.

That was about the best place I could get. I mean, it's a small boat. So it's maybe 5 feet away from the raw water intake.

Also, I thought zinc was more anodic than aluminum?
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Old 20-06-2019, 10:34   #15
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Re: Beta 14 eating anodes at a blistering rate

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Your hanging anode may have a good connection but anodes do not have infinite reach, they must be close to the metal they are supposed to protect.


I thought electrical connection was what was relevant, not physical proximity?
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