No I wasn't duped. I didn't get the AGM's because I expect any better
electrical performance. Quite the opposite. I know that standard wet
cells carefully tended by a knowledgeable person equipped with
hydrometers, thermometers, bottles of distilled water, flashlight,
face shield, and internet connection will give better performance and
cost less than anything out there.

I just don't want to muck around with all that stuff (if you could see
where my batteries are, you would know why. I also don't want free
liquid acid and batteries with a space that gas can mix with oxygen
above the acid in my boat. I know that I'm paying a price in both
money (lots) and performance (slight) for the convenience and safety.

One of the compromises, as you have pointed out, is that the wet cells
are much better at cooling themselves because the liquid electrolyte
can convect around and carry heat to the surface. If a long run under
power with a crude voltage regulator overcharges the wet cells, they
will tolerate it better. If they do boil off some electrolyte, I
would discover it and correct it the next time I wanted to get warm
and fuzzy with my batteries. With AGM's, I'll just be moving the next
expensive replacement a bit closer. Thus, I want to be sure that I am
charging them very carefully.

--

Roger Long



"Larry" wrote in message
...
"Roger Long" wrote in news:2GAQf.7687$Zs1.7219
@twister.nyroc.rr.com:

When running for long periods under power
however, my expensive AGM's are being driven by the alternator
which
isn't significantly different from the ones on the Model T.
Retrofitting my larger spare with an expensive, 3 stage,
temperature
compensated regulator is on my wish list.


Like most boaters who've been sold amazingly overpriced AGM
batteries,
you've been duped into thinking they are some amazingly different
technology than the cheap $89 golf cart batteries from Sam's Club.

The AGM battery is not. It's simply a cheaper way of rolling up
thin lead
plates with glass mats soaked in the same electrolyte used in all
the other
lead-acid batteries. These plates cannot be as thick as the ones in
the
golf cart batteries because the big thick plates are very hard to
bend.
With so limited an amount of electrolyte, that cannot flow in the
gauze and
cool the cell while moving fresh acid in contact with the plates as
the
solution of lead sulphate moves away, it matters little how thin the
plates
are. To get capacity, the plates rolled up are huge!

BOTH these archaic lead-acid batteries are charged just fine with
any
standard alternator with a voltage regulator. They've been working
fine
since way before the Model T was produced....(c;

"Roger Long" wrote in news:geKQf.8326$Da7.1067
@twister.nyroc.rr.com:

If a long run under
power with a crude voltage regulator overcharges the wet cells, they
will tolerate it better.

I've never seen a working "crude regulator" overcharge any lead batteries.
The only thing the batteries care about is 14.2V. They'll take care of the
rest (charging current) quite nicely by themselves.

I know what you mean about battery position on Endeavours. The 35' has a
little battery box under the port quarter berth wedged up under the beer
cooler that protrudes into the tiny space under the port cockpit seat. I
used to have to lay on my belly and slide into the berth backwards, after
removing the bedding and pad, then lay there with my face close to the
batteries where I could get blasted in the face if anything happened while
I was looking at the electrolyte level. We moved the house batteries into
the locker under the starboard cockpit seat in a custom box Cap'n Geoffrey
built in his wood shop. At least you didn't have to have your face into
the cell to see it. Of course, you got to unload the locker to get to the
box...(c;

"Larry" wrote

I've never seen a working "crude regulator" overcharge any lead
batteries.
The only thing the batteries care about is 14.2V.

I have. Boiled those suckers half dry. It was the first boat I ever
sailed that even had a battery and I'd borrowed if for a long cruise
with a girl who was just a hell of a lot of fun to be with on a boat
and a great shipmate but turned out to the hound from hell back on
shore. But, I digress. I figured I'd better stop the bubbling and
let things cool down enough that I could touch the battery so I turned
off the battery switch.

Got back, bought my friend a new battery and alternator. A few days
later, I put in a new voltage regulator for him. A couple days later,
another alternator. Then another voltage regulator. The guy in the
marine store said, "Didn't I see you in here the other day? You
should always replace the voltage regulator and the alternator at the
same time. They're eating each other up." Everything was fine after
that but I'd run through about 75% of my net worth at the time. I
used up the rest flying down to Florida to try and convince that girl
to sail with me forever. That was a much bigger mistake than turning
off the battery switch while the engine was running!

--

Roger Long

"Roger Long" wrote in news:d%TQf.8372$Da7.541
@twister.nyroc.rr.com:

I have. Boiled those suckers half dry. It was the first boat I ever
sailed that even had a battery and I'd borrowed if for a long cruise
with a girl who was just a hell of a lot of fun to be with on a boat
and a great shipmate but turned out to the hound from hell back on
shore. But, I digress. I figured I'd better stop the bubbling and
let things cool down enough that I could touch the battery so I turned
off the battery switch.

That was not a WORKING regulator....That was a SHORTED regulator running
the field current at full maximum. The alternator was putting out over
21V open circuit and charging like hell!

Got back, bought my friend a new battery and alternator. A few days
later, I put in a new voltage regulator for him. A couple days later,
another alternator. Then another voltage regulator. The guy in the
marine store said, "Didn't I see you in here the other day? You
should always replace the voltage regulator and the alternator at the
same time. They're eating each other up." Everything was fine after
that but I'd run through about 75% of my net worth at the time. I
used up the rest flying down to Florida to try and convince that girl
to sail with me forever. That was a much bigger mistake than turning
off the battery switch while the engine was running!



The alternators were probably fine. Overcharging doesn't hurt them as
their inherent internal resistance limits their output current to a safe
level unless they are dead shorted, which usually burns the diode
rectifiers.

He was right about replacing the regulator with the alternator. That's
why you should use alternators with BUILT IN regulators....3 connections.
Power on - Ground - Battery. KISS is always the best...(c;

The series pass transistors in the regulator that regulate the field
winding overheat then short emitter to collector, effectively putting the
field winding directly across the battery terminals. This makes the
output voltage of the alternator go to maximum uncontrolled voltage. The
voltage causes heavy charging boiling the batteries (P=IxE - 16V x 80A =
1280 watts!) It melts the cases on some of the plastic batteries. Not
sure how much of this an uncooled AGM or Gelcell could take before it
explodes....They can't boil like a wetcell does, cooling the cell to the
boiling point.

Sorry about the girl....The battery was inconsequential in comparison...
(c;

"Larry" wrote

Sorry about the girl....The battery was inconsequential in
comparison...
(c;

Well, it was a long, long, time ago in a galaxy far, far away.

You brought up a good point though. A similar failure would spray
acid soaked fiberglass mat all over my engine room. Since I don't
have an engineer standing watch to keep an eye on voltages, what would
you suggest for a simple alarm to let me know that things were
starting to go to hell in a handbasket in the voltage department?
Would you try to trip on overvoltage or just measure battery case
temperature directly?

Oh yeah, the other girl I sailed with in that boat:

We went swimming in Edgartown harbor straight out of the bunk if you
know what I mean. I got the sail up on the cat boat and we sailed out
just as we came off the assembly line. It was race week and the fleet
caught up with us and passed us motoring out to the starting line. A
yawl from the Naval Academy passed close along side. Suddenly,
someone barked an order and the entire crew lined the rail, snapped to
attention, and saluted.

There is nothing, absolutely nothing, half so worthwhile as simply
messing around in boats.

--

Roger Long

"Roger Long" wrote in news:z3oRf.1554$Mj.799
@twister.nyroc.rr.com:

Would you try to trip on overvoltage or just measure battery case
temperature directly?



A voltmeter to watch that is accurate. By the time the temperature
sensor were to alarm the battery was too hot, it would be too late.

You have a long time notice the voltmeter is too high, however, as its
reading is instantaneous. Just mount it next to the oil pressure guage I
hope you're monitoring when the engine is running, not waiting for the
oil pressure alarm to tell you the crank doesn't have any lube and it's
too late to save it.

Just like in my car and truck, I want those guages to be right in front
of me when the engine is running, not some idiot light that comes on too
late. I want to see what the oil pressure and charging voltage is doing.
As to the charging, the Link 10:
http://www.energyoutfitters.com/prod...ntrex_link10.s
htm
is my guage of choice. Not only does it monitor the charging with the
alternator, but it monitors the discharging and AC battery charger's
progress, as well. Every boat with house batteries should be using one.
You can monitor your charging voltage and current, as well as your
discharge current and available amp-hours to plan how long you can run
them down before safely recharging....not waiting until the lights are
too dim...(c;

Larry,

I ruined four golf cart T105's last summer by overcharging them. I
have a Balmar alternator and MH612 regulator. This regulator has a
separate wire that goes to the common positive input to my batery
combiner, and is the 12vdc reference voltage for the regulator. The
lead has an in-line fuse which corroded at one contact, interrupting the
12vdc reference signal to the regulator, and it then went open field to
17v!! We eventually smelled the hydrogen being produced..and awful tangy
smell that is unmistakeable. The plates of the battry actually warped
accordian fashion, and my capacity went from around 100aH (to 12.0v)
down to 35 aH before 12.0v. So replaced them, and the reference leads
fuse assembly. Balmar provided a replacement holder that is much
better, and sealed too.

But they did overcharge a couple times (the symptom came and went due
to vibration giving a good connection sometimes, and a bad one
occasionally. I found it only by chance) causing their being ruined.

Larry DeMers
s/v DeLaMer
Lake Superior

Larry wrote:

"Roger Long" wrote in news:geKQf.8326$Da7.1067
@twister.nyroc.rr.com:


If a long run under
power with a crude voltage regulator overcharges the wet cells, they
will tolerate it better.


I've never seen a working "crude regulator" overcharge any lead batteries.
The only thing the batteries care about is 14.2V. They'll take care of the
rest (charging current) quite nicely by themselves.

I know what you mean about battery position on Endeavours. The 35' has a
little battery box under the port quarter berth wedged up under the beer
cooler that protrudes into the tiny space under the port cockpit seat. I
used to have to lay on my belly and slide into the berth backwards, after
removing the bedding and pad, then lay there with my face close to the
batteries where I could get blasted in the face if anything happened while
I was looking at the electrolyte level. We moved the house batteries into
the locker under the starboard cockpit seat in a custom box Cap'n Geoffrey
built in his wood shop. At least you didn't have to have your face into
the cell to see it. Of course, you got to unload the locker to get to the
box...(c;

In article ,
Larry DeMers wrote:

We eventually smelled the hydrogen being produced.

Yea, right, would you like to try again for what is behind
Door No. 3.....

What you smelled was the Sulfur Dioxode boiling off.....