Hi to all!

I have a 1999 Rinker Fiesta Vee 242 with 5.7EFI Alpha One. This is the first
year the boat has lived in the water in Lake Michigan. i am starting to see
my zincs wear away. They are the original zoncs and have been in salt water.
My questions:

1. Since we are now "living" in freshwater, should i install a Mercathode
system?
2. How can I test for stray current without purchasing an expensive tester
from MerCruiser?
3. Should I also protect my shore power system? - I leave the boat plugged
in with the refriderator and battery charger running.

Thanks for any and all responses!

Dave Alonzi
"Pier Pressure"

"Dave Alonzi" wrote in message
...
Hi to all!

I have a 1999 Rinker Fiesta Vee 242 with 5.7EFI Alpha One. This is the
first
year the boat has lived in the water in Lake Michigan. i am starting to
see
my zincs wear away. They are the original zoncs and have been in salt
water.
My questions:

1. Since we are now "living" in freshwater, should i install a Mercathode
system?

I would - it will help.

2. How can I test for stray current without purchasing an expensive tester
from MerCruiser?

Use a Volt/Ohm Meter (VOM) and check for leaks between ground
connections. In other words, put the VOM on AC (or DC for that
matter) and check the ground between the drive and engine, engine
and battery - etc. That should give you an idea of where the problem
lies - it's quick and dirty but it works for finding ground loops.

3. Should I also protect my shore power system? - I leave the boat plugged
in with the refriderator and battery charger running.

Yes.

Later,

Tom

"= 3. Should I also protect my shore power system? - I leave the boat
plugged
in with the refriderator and battery charger running.


Leave your fridge running on AC power. Turn off all DC components while away
from the boat by turning off all DC circuit breakers on the electrical panel
and also the main battery switches (make sure the bilge pumps are wired
direct to the batteries). Definitely want to leave them powered while away,
but not much reason to have any other 12V device powered up while away. If
the marina has a power outage while you're away, the fridge will probably
hold it's temp just fine until the power returns.

With no DC load on the batteries, there's no reason to leave the charger
turned on. I used to leave my charger turned on years ago. Batteries and
zincs suffered greatly because of the practice. Leaving the charger off
while away has had a huge effect on extending battery and zinc life. Well
maintained batteries will hold their charge just fine while you are away
with no load on them. An even better way to maintain charge while away is
to convert to good quality AGM style batteries. Negligible self-discharge
rate on those, and they last a very long time. Zero maintenance, to boot.

"Jim Woodward" wrote in message
om...
Problem: When you connect an AC line to shore power, there is an
opportunity for low voltage DC to sneak aboard riding on the AC
connection. This usually happens because someone else in the marina
has electrical problems, but can happen even if you're the only boat
on the system. The DC causes electrolysis -- the reverse of
electro-plating -- and can remove metal from things (propellers,
shafts, thru hulls) that you'd like to keep intact. Zincs help
because they are less noble than other things and therefore go away
first.

This is generally less of a problem in freshwater than salt, because
fresh water doesn't conduct electricity anywhere near as well, but it
can happen anywhere. If you're losing zinc, it is happening.

Solutions:
1) As mentioned in a previous post, the best solution is an isolation
transformer -- this is absolutely standard on large vessels. Only the
AC can get through, so you create your own isolated electrical world
even though you're hooked up to shore power. Iso trannies are
bulletproof, old technology, with no moving parts and essentially
nothing to fail unless you vastly overload them.

Problem is, they're heavy and expensive (around 20 pounds and $150 per
kilowatt capacity {a kilowatt is around 8 amps at 120VAC}) They can
get hot (about 5% of the power passing through is lost as heat) and
can hum a little.


2) Next best is a galvanic isolator. This is basically a set of back
to back diodes that pass AC but block small DC voltages. If you keep
within the rating, they'll do fine, but they're more sensitive to
overloads and can, rarely, fail. $160 for 3.5KW from West Marine,
about 3 pounds (1/3 the price and 1/20 the weight of an iso tranny of
the same capacity).

3) Do nothing. Replace your zincs as required before they go away
completely. This will probably be all right, particularly if you keep
an eye on your zincs every week or so. If your marina has DC
problems, I wouldn't want to go for months without checking.


Jim:

I'm not real savvy when it comes to things electrical, especially of the AC
variety, so perhaps you can explain to me what is behind the observation I
made of my own situation, which formed the basis for my post. My boat has a
galvanic isolator, but not a Mercathode system. It is slipped in fresh
water. In its first two years of existence, it was my practice to turn off
all DC devices as well as the master battery switches. Bilge pumps are
wired direct to the batteries. I would always leave on the AC supply to the
fridge, the air conditioner, and the on board AC battery charger when
leaving the boat for the week. The only reason I left the battery charger
turned on was in the remote case of a large chronic leak that might develop
and could after time drain the batteries from extended bilge pump activity.
Thought it would be a good idea to have the charger online in case the bilge
pumps were to drain the batteries in this remote case. The charger is an
intelligent 3-stage rapid electronic switching charger from Charles Marine
(Series 5000). All electrical components are factory installed by Sea Ray.
After owning the boat for two years, the original flooded cell batteries
were cooked and in need of replacement. In addition, I went through zincs
at a rate that I thought was excessive. Probably replaced them 3-4 times in
the two year period. With two outdrives, that's a lot of zincs.

At the two year period, I replaced all three flooded group 27's with
Lifeline AGM group 27's. Love these batteries, but that's another story.
One of the benefits of the AGM's is a very low self-discharge rate. Based
on that, I decided to forego leaving the charger turned on while away from
the boat. Figured I'd take the chance of extended bilge pump activity
(which has never happened, my bilge is always dry as a bone), in favor of
not cooking these relatively expensive batteries. I still leave the AC
supply to the fridge as well as the air conditioner turned on while away.
Where I live, if I didn't leave the air turned on with the thermostat set to
80 degrees or so, the cabin temp would climb well into the 140+ degree
territory, making life a living hell for the fridge. All DC devices as well
as the main battery switches are turned off while away. I'm still in the
same slip, and my immediate neighbors are the same as well. It has been two
years since I made the change of not leaving the battery charger turned on
while away from the boat. The difference between the second two years and
the first two years is that the batteries are as strong today as when they
were new (partially due to those terrific AGM's no doubt), and I have yet to
notice any significant amount sacrificial activity from the zincs. They
have yet to need replacing in the last two years. The only thing I know to
attribute this difference in zinc activity to is the fact that I no longer
keep the battery charger turned on while away from the boat. I do keep the
charger turned I'm on while on the boat and in the slip, just as I always
have done.

Any comments as to the battery charger/zinc relationship?

Your very comprehensive description makes diagnosis at a distance
maybe easier, but no less risky. With that risk in mind, read on.....

Zincs are there to protect valuable stuff if the valuable stuff gets a
little positive with respect to the water. So, the question is, how
did the outdrives get a little positive with the charger running?

We can probably rule out the AC line, because a) you have isolaters
and b) the ABYC rules prohibit a connection between any of the AC
wires (any of black, white, and green) and the boat ground -- with
isolaters, you rely on the shore power connection to tie the green and
neutral (white) to ground at the system entrance.

So, let's look at the charger. The charger is an AC appliance so its
case should be connected firmly to the green AC safety ground. Its DC
negative output should be floating -- not connected to the case -- or
else it would violate the rule that you don't ground the green on the
boat. You could check this -- with the charger unplugged and the DC
side disconnected, an ohmeter (a DVM on ohms reading) should read many
megohms between the case and either DC terminal and should read zero
(or almost zero -- low readings are hard) between the case and the
ground pin (the long round one) on the AC plug.

While you have the DVM out, you should check to see that the green
ground is in fact not connected to boat ground. This is a little
tricky, because the boat's green wire is connected to the shoreside
system ground which is at the electrical entrance of the system to the
facility. The boat ground will be connected to the water and,
therefore, through the earth to the other end of the green ground.
The best way to do this is to measure between the green wire of the AC
and an engine block -- with the shore power connected, you'll get an
unpredictable reading in fresh water -- certainly not zero and perhaps
quite high -- depends on how clean the water is. With the shore power
disconnected, however, it should read many megohms.

Assuming all these reading are OK, I would look to make sure that all
the bonding is good. In an ideal system, there is a "common ground
point" where all the metal on the boat (except AC appliances) is
connected. There should at a minimum be good connections between the
charger DC negative, the alternator negatives, the battery(s), the
starters, the engine blocks, and the outdrives. These should all tie
either to one point or in one line -- no loops. Note that generally
you need separate wires for all of this, not relying on the metal to
metal contact in the engines and outdrives. The point is to keep
everything at exactly the same voltage -- gaskets and so forth can get
in the way of that when you're trying to avoid differences of tenths
of a volt or less.

Now, all of this should have been done by your boat's manufacturer --
and it probably was. Over time, though, these connections can loosen
or become corroded so you get small differences in voltage, enough to
cause zinc problems, even in fresh water.

All of this assumes, by the way, that there's nothing fundamentally
wrong inside the charger. Switching chargers are wonderful devices --
basically the switch turns the AC on maybe a million times a second
and then turns it off as soon as the output is at the desired voltage.
This technology eliminates a heavy transformer and reduces the output
ripple (ie the 60hz component) to almost nothing. Because there's no
transformer isolating things, however, they have to be carefully
designed to keep the AC and DC systems separate. I don't know Charles
Marine, so I can't comment, but the fact that it fried your first
batteries is an indication that something isn't perfect -- a charger
should be able to keep wet cells topped up without using much water at
all.

Not perhaps, as helpful as you'd like, and certainly not a definitive
answer, but these things are hard, even in person.....


Jim Woodward
www.mvfintry.com




"RG" wrote in message news:ZTyYa.38171$Bp2.19589@fed1read07...
"Jim Woodward" wrote in message
om...
Problem: When you connect an AC line to shore power, there is an
opportunity for low voltage DC to sneak aboard riding on the AC
connection. This usually happens because someone else in the marina
has electrical problems, but can happen even if you're the only boat
on the system. The DC causes electrolysis -- the reverse of
electro-plating -- and can remove metal from things (propellers,
shafts, thru hulls) that you'd like to keep intact. Zincs help
because they are less noble than other things and therefore go away
first.

This is generally less of a problem in freshwater than salt, because
fresh water doesn't conduct electricity anywhere near as well, but it
can happen anywhere. If you're losing zinc, it is happening.

Solutions:
1) As mentioned in a previous post, the best solution is an isolation
transformer -- this is absolutely standard on large vessels. Only the
AC can get through, so you create your own isolated electrical world
even though you're hooked up to shore power. Iso trannies are
bulletproof, old technology, with no moving parts and essentially
nothing to fail unless you vastly overload them.

Problem is, they're heavy and expensive (around 20 pounds and $150 per
kilowatt capacity {a kilowatt is around 8 amps at 120VAC}) They can
get hot (about 5% of the power passing through is lost as heat) and
can hum a little.


2) Next best is a galvanic isolator. This is basically a set of back
to back diodes that pass AC but block small DC voltages. If you keep
within the rating, they'll do fine, but they're more sensitive to
overloads and can, rarely, fail. $160 for 3.5KW from West Marine,
about 3 pounds (1/3 the price and 1/20 the weight of an iso tranny of
the same capacity).

3) Do nothing. Replace your zincs as required before they go away
completely. This will probably be all right, particularly if you keep
an eye on your zincs every week or so. If your marina has DC
problems, I wouldn't want to go for months without checking.


Jim:

I'm not real savvy when it comes to things electrical, especially of the AC
variety, so perhaps you can explain to me what is behind the observation I
made of my own situation, which formed the basis for my post. My boat has a
galvanic isolator, but not a Mercathode system. It is slipped in fresh
water. In its first two years of existence, it was my practice to turn off
all DC devices as well as the master battery switches. Bilge pumps are
wired direct to the batteries. I would always leave on the AC supply to the
fridge, the air conditioner, and the on board AC battery charger when
leaving the boat for the week. The only reason I left the battery charger
turned on was in the remote case of a large chronic leak that might develop
and could after time drain the batteries from extended bilge pump activity.
Thought it would be a good idea to have the charger online in case the bilge
pumps were to drain the batteries in this remote case. The charger is an
intelligent 3-stage rapid electronic switching charger from Charles Marine
(Series 5000). All electrical components are factory installed by Sea Ray.
After owning the boat for two years, the original flooded cell batteries
were cooked and in need of replacement. In addition, I went through zincs
at a rate that I thought was excessive. Probably replaced them 3-4 times in
the two year period. With two outdrives, that's a lot of zincs.

At the two year period, I replaced all three flooded group 27's with
Lifeline AGM group 27's. Love these batteries, but that's another story.
One of the benefits of the AGM's is a very low self-discharge rate. Based
on that, I decided to forego leaving the charger turned on while away from
the boat. Figured I'd take the chance of extended bilge pump activity
(which has never happened, my bilge is always dry as a bone), in favor of
not cooking these relatively expensive batteries. I still leave the AC
supply to the fridge as well as the air conditioner turned on while away.
Where I live, if I didn't leave the air turned on with the thermostat set to
80 degrees or so, the cabin temp would climb well into the 140+ degree
territory, making life a living hell for the fridge. All DC devices as well
as the main battery switches are turned off while away. I'm still in the
same slip, and my immediate neighbors are the same as well. It has been two
years since I made the change of not leaving the battery charger turned on
while away from the boat. The difference between the second two years and
the first two years is that the batteries are as strong today as when they
were new (partially due to those terrific AGM's no doubt), and I have yet to
notice any significant amount sacrificial activity from the zincs. They
have yet to need replacing in the last two years. The only thing I know to
attribute this difference in zinc activity to is the fact that I no longer
keep the battery charger turned on while away from the boat. I do keep the
charger turned I'm on while on the boat and in the slip, just as I always
have done.

Any comments as to the battery charger/zinc relationship?

Hey thanks for your very thorough reply, Jim. Quite a bit of food for
thought.