On Jun 15, 9:46 am, Salomon Fringe wrote:
...If you use a main engine or a generator
to charge then I think AGM or gel are out of the question.

And you believe this because...? I and many others have gotten many
years of outstanding service from AGMs used in exactly this way. I've
got nothing against regular old flooded batteries. They're certainly
the best in terms of capacity per monetary unit or capacity per weight
for lead acid. But the article you're quoting is being wildly, even
absurdly unfair in its comparison of the types of lead acid
batteries. He gives AGMs a particularly bad rap by asserting that
they are essentially the same thing as a "maintenance free" starting
battery. His argument seems to be "well, they've got thin plates and
you can't add water to them so they must outgas like mad if you charge
them fast and the plates must fail quickly because they are thin." Of
course, if that were true AGMs would die quickly in normal use. Yet,
I and many other folks, have AGMs that have lasted for 8+ years
despite being deep cycled and charged at significantly faster rates
than flooded cells. How can that be? The answer is that the author
of your article either doesn't know the differences between an AGM and
a cheap maintence free starting battery or is being intentionally
misleading.

As far as I know all AGMs are "valve regulated". Certainly all the
major players are. Under normal charging they recombine virtually all
gas. While massive overcharging will cause them to vent, modest
amounts of over voltage will not hurt them noticeably. Indeed, all of
the manufactures that I've looked at recommend periodically equalizing
them. Generally you can put all the amps you've go into them as long
as you regulate the voltage (max between 14.0 and 14.6 depending on
the temperature and the particular battery). Even so regulated their
acceptance rates are higher than deep cycle flooded batteries and
charge times are quicker.

AGMs do have thin plates. But, those plates are packed tightly into
the glass mat and physically very well supported. So, they are less
prone to physical failure than the thin plates in flooded starting
batteries that need to be largely self-supporting. And, at the same
time, they have more surface area than flooded deep cell batteries.
The net result is that AGMs have very low internal resistance compared
to other deep cycle batteries and are more durable. Low resistance
also reduces gassing.
....
If you read the article then you will also have read that if you are
willing to use 'reasonable charging rates' (=slow charging), standard
lead-acid is 'maintenance free' just like AGM and gel.
But AGM and gel are much more expensive.

I've read the article. It is total BS. AGMs are not gels or cheap
sealed starting batteries. All his conclusions follow from a false
assumption and no evidence for the conclusions is provided.

-- Tom.

wrote:

On Jun 15, 9:46 am, Salomon Fringe wrote:

...If you use a main engine or a generator
to charge then I think AGM or gel are out of the question.


And you believe this because...? I and many others have gotten many
years of outstanding service from AGMs used in exactly this way. I've
got nothing against regular old flooded batteries. They're certainly
the best in terms of capacity per monetary unit or capacity per weight
for lead acid. But the article you're quoting is being wildly, even
absurdly unfair in its comparison of the types of lead acid
batteries. He gives AGMs a particularly bad rap by asserting that
they are essentially the same thing as a "maintenance free" starting
battery. His argument seems to be "well, they've got thin plates and
you can't add water to them so they must outgas like mad if you charge
them fast and the plates must fail quickly because they are thin." Of
course, if that were true AGMs would die quickly in normal use. Yet,
I and many other folks, have AGMs that have lasted for 8+ years
despite being deep cycled and charged at significantly faster rates
than flooded cells. How can that be? The answer is that the author
of your article either doesn't know the differences between an AGM and
a cheap maintence free starting battery or is being intentionally
misleading.

As far as I know all AGMs are "valve regulated". Certainly all the
major players are. Under normal charging they recombine virtually all
gas. While massive overcharging will cause them to vent, modest
amounts of over voltage will not hurt them noticeably. Indeed, all of
the manufactures that I've looked at recommend periodically equalizing
them. Generally you can put all the amps you've go into them as long
as you regulate the voltage (max between 14.0 and 14.6 depending on
the temperature and the particular battery). Even so regulated their
acceptance rates are higher than deep cycle flooded batteries and
charge times are quicker.

AGMs do have thin plates. But, those plates are packed tightly into
the glass mat and physically very well supported. So, they are less
prone to physical failure than the thin plates in flooded starting
batteries that need to be largely self-supporting. And, at the same
time, they have more surface area than flooded deep cell batteries.
The net result is that AGMs have very low internal resistance compared
to other deep cycle batteries and are more durable. Low resistance
also reduces gassing.
...

If you read the article then you will also have read that if you are
willing to use 'reasonable charging rates' (=slow charging), standard
lead-acid is 'maintenance free' just like AGM and gel.
But AGM and gel are much more expensive.


I've read the article. It is total BS. AGMs are not gels or cheap
sealed starting batteries. All his conclusions follow from a false
assumption and no evidence for the conclusions is provided.

-- Tom.

That's interesting. Do you have the actual manufacturers discharge
graphs that the author says they -for some reason- don't seem to supply?
Personally I would not make a decision on hearing that so-and-so
deep-cycled AGM's for 8+ years without any problems. How often and how
deeply have these really been cycled, how quickly were they charged, at
what temperature. Plenty of unknowns. Myself, I heard of people that
have definitely NOT been able to deep cycle their AGM's 8+ years. Far
from it, actually. The author claims that a Dutch magazine got 500
responses confifming his stance though.
Before I would agree that the author was talking nonsense, I'd like to
see hard (manufacturers) data that would really prove this. If the AGM
manufacturers have nothing to hide then that info will be advertised on
their websites.

On Jun 15, 12:32 pm, Salomon Fringe wrote:
....
That's interesting. Do you have the actual manufacturers discharge
graphs that the author says they -for some reason- don't seem to supply?

Just go look them up. There's no secret. I don't know why the author
seems to think there is. Indeed, the article you posted in reply to
Roger down the thread has some good info on this. Did you read it?
In any case, the author of your first link doesn't provide a single
test or citation to support his views, so why should we believe him?

... If the AGM
manufacturers have nothing to hide then that info will be advertised on
their websites.

It is.

--Tom.

wrote:

On Jun 15, 12:32 pm, Salomon Fringe wrote:
...

That's interesting. Do you have the actual manufacturers discharge
graphs that the author says they -for some reason- don't seem to supply?



Just go look them up. There's no secret. I don't know why the author
seems to think there is. Indeed, the article you posted in reply to
Roger down the thread has some good info on this. Did you read it?


Yes I actually have the printed version of that doc, but I don't think
there is even a hint of being able to use a AGM for 8+ years while
deep-cycling... ?

In any case, the author of your first link doesn't provide a single
test or citation to support his views, so why should we believe him?


... If the AGM
manufacturers have nothing to hide then that info will be advertised on
their websites.



Err, I was hoping you would have the links handy... ;-)


It is.

--Tom.

On Jun 15, 1:23 pm, Salomon Fringe wrote:
....
Yes I actually have the printed version of that doc, but I don't think
there is even a hint of being able to use a AGM for 8+ years while
deep-cycling... ?

Well, I don't think I said that. What I was trying to say is that the
author doesn't seem to have had any trouble coming up with published
data. For instance he notes that deep cycle flooded cells ("semi-
traction") get 350 cycles at 60% DOD (which is deep cycling) while
AGMs get 650-800 depending on construction and chemistry. Service
life depends on how you use them but the AGMs look much better than
the semi-traction batteries for deep cycle use. His service life
numbers suggest that some AGMs will be expected to last 10 years.
AGMs have only been popular in marine use for less than a decade so it
may be hard to get real numbers. My experience has been fantastic.
YMMV... I think some of the very negative responses in the "Dutch
magazine" (if they exist, got a citation?) might have been for gel
cels. AGMs are not gel cells and linking them is bogus (or maybe even
dishonest). AGMs have really good cycling numbers and they are
published and you've even posted a link to them. So the Sterling
guy's conclusion that you should avoid AGMs because they have "poor
cycling numbers" is hard to figure. The rest of his arguments seem to
be based on straw men and thin air, too. Who is this guy?

Although it's a little off topic http://www.proboat-digital.com/proboat/20080203/
is interesting and has some insight into usage issues.

....
Err, I was hoping you would have the links handy... ;-)

I was hoping you'd do your own. If you can't google I'll do it for
you, but last time I looked both Full River and Lifeline (Concord) had
graphs and spec sheets on-line for their AGMs. You may have to plot
data from your favorite flooded deep cycle battery for comparison but
if the flooded guys have nothing to hide their data will be on-line,
too... ;-)

I'm not trying to sell AGMs. There are good reasons that they don't
use them in golf carts, for instance. But the guy at Sterling seems
to have decided that he hates AGMs and then gone off to figure out
why.

--Tom.

On Sun, 15 Jun 2008 15:20:55 -0700 (PDT), "
wrote:

His service life
numbers suggest that some AGMs will be expected to last 10 years.
AGMs have only been popular in marine use for less than a decade so it
may be hard to get real numbers. My experience has been fantastic.

I have heard the same from others whom I respect. I will probably
convert one of my house banks to AGMs in the future.

"Wayne.B" wrote in message
...
On Sun, 15 Jun 2008 15:20:55 -0700 (PDT), "
wrote:

His service life
numbers suggest that some AGMs will be expected to last 10 years.
AGMs have only been popular in marine use for less than a decade so it
may be hard to get real numbers. My experience has been fantastic.

I have heard the same from others whom I respect. I will probably
convert one of my house banks to AGMs in the future.

While I cannot comment on AGM batteries, my experience with gel batteries
may be of interest.
In 2005 I imported a boat from Florida to Norway. The survey was carried out
in mid March and the batteries were Ok and powered up all auxiliaries
properly.
Three months later she arrived in Norway and the batteries were flat
because, as recommended by the makers, the refrigerator was connected
directly to the batteries rather than going through the panel and nobody had
thought to disconnect it.
I tried to charge the batteries with a powerful charger and it could get no
current at all to pass through the batteries-they blocked the current
completely..
I found that very surprising although I had half expected them to accept,
but not retain, a charge.

Wayne.B wrote:

On Sun, 15 Jun 2008 15:20:55 -0700 (PDT), "
wrote:


His service life
numbers suggest that some AGMs will be expected to last 10 years.
AGMs have only been popular in marine use for less than a decade so it
may be hard to get real numbers. My experience has been fantastic.


I have heard the same from others whom I respect. I will probably
convert one of my house banks to AGMs in the future.

I hope you were also thinking of adding another charger, since if your
other bank is not AGM you will need it.

wrote:
On Jun 15, 1:23 pm, Salomon Fringe wrote:
...

Yes I actually have the printed version of that doc, but I don't think
there is even a hint of being able to use a AGM for 8+ years while
deep-cycling... ?


Well, I don't think I said that. What I was trying to say is that the
author doesn't seem to have had any trouble coming up with published
data. For instance he notes that deep cycle flooded cells ("semi-
traction") get 350 cycles at 60% DOD (which is deep cycling) while
AGMs get 650-800 depending on construction and chemistry. Service
life depends on how you use them but the AGMs look much better than
the semi-traction batteries for deep cycle use. His service life
numbers suggest that some AGMs will be expected to last 10 years.
AGMs have only been popular in marine use for less than a decade so it
may be hard to get real numbers. My experience has been fantastic.
YMMV... I think some of the very negative responses in the "Dutch
magazine" (if they exist, got a citation?) might have been for gel
cels. AGMs are not gel cells and linking them is bogus (or maybe even
dishonest). AGMs have really good cycling numbers and they are
published and you've even posted a link to them. So the Sterling
guy's conclusion that you should avoid AGMs because they have "poor
cycling numbers" is hard to figure. The rest of his arguments seem to
be based on straw men and thin air, too. Who is this guy?

Although it's a little off topic http://www.proboat-digital.com/proboat/20080203/
is interesting and has some insight into usage issues.

...

Err, I was hoping you would have the links handy... ;-)


I was hoping you'd do your own. If you can't google I'll do it for
you, but last time I looked both Full River and Lifeline (Concord) had
graphs and spec sheets on-line for their AGMs. You may have to plot
data from your favorite flooded deep cycle battery for comparison but
if the flooded guys have nothing to hide their data will be on-line,
too... ;-)

I'm not trying to sell AGMs. There are good reasons that they don't
use them in golf carts, for instance. But the guy at Sterling seems
to have decided that he hates AGMs and then gone off to figure out
why.

--Tom.


Well the author of the Victron article really did a good job and I have
used his info extensively but I did realize that Victron sells gel and
AGM but nothing else in terms of batteries so I assumed a slight nudge
towards their product line in the numbers. Also his pricing info in the
comparison was way off from what I found, e.g. full traction was just
50% of the price he stated.
The amount of active material in any lead acid battery, be it flooded
gel or AGM is what makes the battery survive longer for cycling, and so
comparing the most expensive thick-plate AGM with standard flooded cells
does not make sense. We should compare AGM and flooded batteries that
have equal weight (lead) or, for a different comparison, equal price. I
think that in real life, a flooded cell will hugely outperform the AGM
for cycling use because you can equalize a flooded cell to refresh weak
cells, because you cannot monitor the temperature of each battery (let
alone every cell) while charging which means guaranteed overcharging of
some batteries/cells - destroying your typical AGM cell. Of course it is
cheaper, too.

Returning to the Victron article, even with my suspicions about the
author towards his own product line, what I distilled from the article
was that tubular plate traction batteries are the best deal for serious
cycling, not gel or AGM. I did my research two years ago so things may
have changed but I don't think the numbers can have changed that much.

I would like to know from people who have REALLY deepcycled their AGM's
500 times (anybody counting?) and are still using them. If these exist I
believe that you will find they paid as much for their AGMS as they
would have for equivalent capacity traction - which would last at least
twice as long.

On Jun 16, 12:58 am, Salomon Fringe wrote:
Well the author of the Victron article really did a good job and I have
used his info extensively but I did realize that Victron sells gel and
AGM but nothing else in terms of batteries so I assumed a slight nudge
towards their product line in the numbers. ...

Now wait. You're accusing the guy of lying to sell overpriced
batteries that will fail if they ever get used and you're saying
you've used his "info" extensively? Is this wise?

Also his pricing info in the
comparison was way off from what I found, e.g. full traction was just
50% of the price he stated.

Pricing changes all the time. Still, I think he was testing 24v full
traction batteries which might well explain the difference.

... in real life, a flooded cell will hugely outperform the AGM
for cycling use because you can equalize a flooded cell to refresh weak
cells, because you cannot monitor the temperature of each battery (let
alone every cell) while charging which means guaranteed overcharging of
some batteries/cells - destroying your typical AGM cell. Of course it is
cheaper, too.

Just for the record, you can equalize AGMs periodically without
destroying them. The manufacturers even recommend it. I use a
temperature compensated charging system with my AGMs. I don't
understand what you're saying about not being able to monitor the
temp. Your theory about cycling is interesting and testable but it
goes against the published data. Given that I think the burden of
proof lies with you. Go do some tests that suggest that the
datasheets and experts are wrong and you'll garner a lot of
attention.

....
I would like to know from people who have REALLY deepcycled their AGM's
500 times (anybody counting?) and are still using them. If these exist I
believe that you will find they paid as much for their AGMS as they
would have for equivalent capacity traction - which would last at least
twice as long.

I presume what you're saying here is that my experience of REALLY
sailing three times around the Pacific and REALLY living on my boat
full time and REALLY charging my batteries using my engines is REALLY
not valid because you REALLY don't want to hear it? I'm not claiming
to be a representative sample but my experience suggests to me that
some of your concerns about AGMs are overstated. I cruise extensively
and keep in touch with many who do the same and I haven't heard any
negative feedback about AGMs. Again, that's not a random sampling,
but still, here we are in a widely read newsgroup discussing AGMs.
Where are the voices saying "damn, I put one of those in and smoked it
in a week"? Where are the 500 e-mailers who wrote into the Dutch
magazine to complain about AGMs?

I think Roger is right. The discussion has wandered off a bit. I'm
not trying to get into a ****ing match. I don't sell batteries. When
I bought my AGMs it wasn't a slam-dunk, easy decision. I can
understand why lots of folks choose differently. I've been very happy
with the way my AGMs have worked, but performance was not the only
criteria in my decision. As I type this at my nav station, I have two
8D AGMs just a foot or so away from my toes. Safety and aesthetics
have some value for me, too. AGMs are much more shock resistant than
flooded or gel batteries and that makes them less prone to internal
plate failures and shorts. Reliability is important, too. And so it
goes. In different circumstances I can easily see myself doing things
differently. There's lots of room for discussion of the pros and cons
of various systems. My only serious beef with the discussion so far
is with some of the arguments and assertions in your first link which
are, to be kind, bogus.

--Tom.