I just saw a link to a very helpful site on batteries in a thread below but
now I can't find the OP. Thanks to whoever posted it.

I particularly recommend this page:

http://jgdarden.com/batteryfaq/carfaq1.htm

Note the number of times he says "or use AGM batteries" after describing
something you must do with safety glasses and other gear.

Note especially item number 1.13 where he says:

1.13. Do NOT use wet lead-acid batteries around salt water. If salt water is
mixed with the battery's electrolyte, deadly chlorine gas is produced. Only
use sealed AGM (Ca/Ca) or Gel Cell (Ca/Ca) VRLA batteries around salt water.

Good advice I think.

--
Roger Long

"Roger Long" wrote in
:

1.13. Do NOT use wet lead-acid batteries around salt water. If salt
water is mixed with the battery's electrolyte, deadly chlorine gas is
produced. Only use sealed AGM (Ca/Ca) or Gel Cell (Ca/Ca) VRLA
batteries around salt water.

Good advice I think.



The advice is Ca/Ca, allright. AGM and Gellcell batteries ARE lead acid
batteries, just like wetcells.

Wetcells PROPERLY SECURED INTO THE BATTERY BOX are just as safe as the
other batteries for thousands more because they have gas vent caps on
them that seal out the seawater and seal in the electrolyte in case you
pitch pole the boat doing something stupid or a rogue wave hits.

Most batteries, regardless of technology, are just sitting in the
battery hole waiting to come out upside down to kill someone or start a
fire hanging on their poorly installed battery cables.

A recent sinking at an unnamed marina of a 40' sloop who's bilge pump
clogged, causing the level of the water OUTSIDE the hull to be higher
than the lip of the defective marine head INSIDE the hull....valves left
open so it could flood hard and sink....prove there is really no problem
with wetcell batteries in boats.

The battery compartment of this sloop went underwater for about a week,
the boat simply laying low in the water before someone noticed it and
did something for her. The DC power in both the two AGM house batteries
and the wetcell regular car starting battery ate the terminals off BOTH
types of batteries conducting through the seawater between the posts.
The bolts finally electrolyzed away and the cables were simply left
hanging underwater in the battery box under the cabin sole....it was
that long.

All 3 batteries survived the sinking! The AGMs had plenty of power left
once you touched the cables to where the posts USED to be, indicating
they were not sea water flooded inside their crazy battery cell tubes.
Likewise, the Walmart sourced car starting battery used to crank the
Yanmar on the cheap also still had around 12.6 volts on its rotted away
lead posts and seawater did NOT make it past the electrolyte traps in
the pressed in multiple hole cell plugs that fit flush with the top of
the plastic case.

They were all fine....wetcells and all.....

Obviously this was NOT the case for the fake interior panels made of
expensive wood-veneered plywood, which all came apart as the sea water
soaked up the cardboard base.....and seats.....and everything made of
metal was simply eaten...pots/pans/utensils/even the beer cans floating
around inside the ice box....9c;

What a terrible waste of good beer.....

wrote:

On Mon, 21 Jul 2008 03:24:50 +0000, Larry wrote:

"Roger Long" wrote in
:

1.13. Do NOT use wet lead-acid batteries around salt water. If salt
water is mixed with the battery's electrolyte, deadly chlorine gas is
produced. Only use sealed AGM (Ca/Ca) or Gel Cell (Ca/Ca) VRLA
batteries around salt water.

Good advice I think.

Not really so much

The advice is Ca/Ca, allright. AGM and Gellcell batteries ARE lead acid
batteries, just like wetcells.

Wetcells PROPERLY SECURED INTO THE BATTERY BOX are just as safe as the
other batteries for thousands more because they have gas vent caps on
them that seal out the seawater and seal in the electrolyte in case you
pitch pole the boat doing something stupid or a rogue wave hits.


When you crack the case of an AGM, however, it does not leak acid like a flooded
battery. Even batteries that are tied down sometimes break free in a capsize, or
rough conditions. And if something else is thrown against them hard enough, that
may also release the contents.

If you are going to power something with gasoline, that's a whole lot
more hazardous - as in more likely to cause a problem - than having
batteries thrown around and release their contents. If you are in
rough enough conditions that your batteries are going to be thrown
around even if they are tied down, then you have big problem, and just
changing the type of battery you have won't help you much.

wrote in :

When you crack the case of an AGM, however, it does not leak acid like
a flooded battery. Even batteries that are tied down sometimes break
free in a capsize, or rough conditions. And if something else is
thrown against them hard enough, that may also release the contents.




If you crack open an AGM, the plates will probably touch and any acid that
may have leaked will be a moot point after the explosion of all the other
cells....

On Jul 21, 5:57*am, Larry wrote:
...
If you crack open an AGM, the plates will probably touch and any acid that
may have leaked will be a moot point after the explosion of all the other
cells....

Anything is possible, but having the plates touch on an AGM is not an
easy thing. Before they can touch the glass mat (an insulator) has to
be removed. From the comment above and several other statements
you've made in the battery discussions of late, I think you mistaken
about how AGMs are constructed. There is a good picture of an AGM cut
open and an interesting article he
http://www.proboat-digital.com/proboat/20080203/

-- Tom.

wrote:

On Mon, 21 Jul 2008 08:47:05 -0400, Rosalie B.
wrote:

wrote:

On Mon, 21 Jul 2008 03:24:50 +0000, Larry wrote:

"Roger Long" wrote in
:

1.13. Do NOT use wet lead-acid batteries around salt water. If salt
water is mixed with the battery's electrolyte, deadly chlorine gas is
produced. Only use sealed AGM (Ca/Ca) or Gel Cell (Ca/Ca) VRLA
batteries around salt water.

Good advice I think.

Not really so much

The advice is Ca/Ca, allright. AGM and Gellcell batteries ARE lead acid
batteries, just like wetcells.

Wetcells PROPERLY SECURED INTO THE BATTERY BOX are just as safe as the
other batteries for thousands more because they have gas vent caps on
them that seal out the seawater and seal in the electrolyte in case you
pitch pole the boat doing something stupid or a rogue wave hits.


When you crack the case of an AGM, however, it does not leak acid like a flooded
battery. Even batteries that are tied down sometimes break free in a capsize, or
rough conditions. And if something else is thrown against them hard enough, that
may also release the contents.

If you are going to power something with gasoline, that's a whole lot
more hazardous - as in more likely to cause a problem - than having
batteries thrown around and release their contents. If you are in
rough enough conditions that your batteries are going to be thrown
around even if they are tied down, then you have big problem, and just
changing the type of battery you have won't help you much.

Yeah, my car has seatbelts, so why worry about having airbags. :')

We have old cars and they don't have airbags. g

Ask anyone who has ever had battery acid flung around in a boat, and
then get back to me about whether it's an important issue.

How many people are there who have had battery acid flung around the
boat?

Gasoline is a completely different discussion, as is the one
concerning having a 50 foot tall metal pole mounted on your boat.
There are lots of potential dangers on a boat. It makes sense to
mitigate as many as you can - within reason.

When we used to have to assess penalties for violations of the health
and safety standards we had to use four factors and two of them were
hazardousness (a one level hazard was a cut or rash and a four level
hazard was death or permanent physical disability) and one of them was
likelihood of something happening. I would rate:

Fire from gasoline - hazard 3 and likelihood 2
Tall metal pole - hazard 1 or 2 and likelihood about a 2, and
Danger of battery acid being flung around a boat - hazard 2, and
likelihood 1

You may disagree.

wrote

Now that I see all of this, I wonder if perhaps in the long term, AGM
batteries are really about the same cost as the more dangerous and
unreliable flooded batteries.

You may disagree.

The electrical system specialists who did the final design and engineering
for my 81 foot research vessel do agree and said pretty much just what you
did. They do both land based emergency power systems for things like phone
company switching centers and sophisticated vessel systems. Pretty
knowledgeable guys.

According to them, you didn't even need to factor in the safety of AGM's to
justify their use.

--
Roger Long

On Jul 21, 8:27*am, " wrote:
...*There is a good picture of an AGM cut
open and an interesting article hehttp://www.proboat-digital.com/proboat/20080203/

I should have added that you need to go to Contents-Breakthrough.
The AGM in question has its top cut off and is lying on its side. No
acid spilled out no plates shorted...

-- Tom.

"Roger Long" wrote:

wrote

Now that I see all of this, I wonder if perhaps in the long term, AGM
batteries are really about the same cost as the more dangerous and
unreliable flooded batteries.

You may disagree.

The electrical system specialists who did the final design and engineering
for my 81 foot research vessel do agree and said pretty much just what you
did. They do both land based emergency power systems for things like phone
company switching centers and sophisticated vessel systems. Pretty
knowledgeable guys.

According to them, you didn't even need to factor in the safety of AGM's to
justify their use.

Bob converted a car to run on batteries. He had 18 of them. AGMs
were significantly more expensive and didn't last any longer Same
with the boat - I think we have two battery banks - 96 amp hours or
something like that. And the AGM batteries (I have heard) have much
more tricky charging requirements. Now maybe that has changed in the
past 10 years - probably so. And if we were setting up the system
now, we might do it with AGM batteries. But we are not, so we won't.

If they had special charging requirments and this was 10 years ago, they
were probably gel cells with are different and often confused with AGM's.

--
Roger Long