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.