You make an excellent point that no battery is safe. Anytime you store
up that much power in a small package there is going to be risk when
things go wrong. AGM's certainly can explode if abused.

However, explosions are only part of it. The free liquid acid,
corrosive fumes, and explosive vapors of wet cells are all minimized
with AGM's. If something does go wrong and one blows up, the acid
impregnated mat in the AGM should be less dangerous and easier to
clean up than the liquid.

This is analogous to the gas / diesel propulsion question. If you need
the very best performance and power to weight ration, you have to go
with gas and learn to keep large amounts of explosive fume producing
liquid on board. With care, understanding, and proper equipment, gas
can be made acceptably safe. Diesel is not perfectly safe but it is
much safer and has other advantages such as more moisture tolerant
ignition.

Despite the blanket statement I started this thread with, there are
certainly operational situations in which I might choose wet cells. I
wouldn't expect them in normal yachting situations though.

Speaking of internal shorts, the AGM, with everything held in place
with the glass mat should be far less likely to short than the wet
cell where chunks can fall off the plates and there is only liquid to
keep them from moving around.

--

Roger Long

In article ,
says...

Speaking of internal shorts, the AGM, with everything held in place
with the glass mat should be far less likely to short than the wet
cell where chunks can fall off the plates and there is only liquid to
keep them from moving around.

I would agree. Not just chunks but in an aging and poorly maintained
battery a constgant rain of debris to the bottom of the case where it
eventually shorts out the plates when a heavy load is applied. Our
problem was no-name batteries to begin with which the yard failed to
maintain over a long in-water layup. The following March when moving the
boat I advanced the throttle from slow to WOT and BLAM!

Does ABYC require that AGM batteries have a battery box?

I found the ABYC Standard E-10.6 Storage Batteries - Installation.
Apparently, it does not require a battery box for any type of battery.

Paul
"Paul L" wrote in message
newsNYZd.8872$Z07.4338@trnddc02...
Does ABYC require that AGM batteries have a battery box?

Although a box is not required, there are other requirements that are
best satisfied with a box:

From 1998:

E-10.7 INSTALLATION
E-10.7.1 If the mounting surfaces of components of the boat in the
immediate vicinity of the battery are of a material attacked by the
electrolyte, a mounting means shall be provided that is made of
material that is not damaged by electrolyte.
E-10.7.2 Provision shall be made to contain leakage and spillage of
electrolyte.
E-10.7.3 Fasteners for the attachment of battery boxes or trays shall
be isolated from areas intended to collect spilled electrolyte.
E-10.7.4 Each installed battery shall not move more than one inch
(25mm) in any direction when a pulling force of 90 pounds (41kg) or
twice the battery weight, whichever is less, is applied through the
center of gravity of the battery as follows;
E-10.7.4.1 vertically for a duration of one minute, and
E-10.7.4.2 horizontally and parallel to the boat's centerline, for a
duration of one minute fore and one minute aft, and
E-10.7.4.3 horizontally and perpendicular to the boat's centerline for
a duration of one minute to starboard and one minute to port.
E-10.7.5 No battery shall be installed directly above or below a fuel
tank, fuel filter, or fitting in a fuel line.
NOTE: This does not prohibit a battery from being installed directly
above or below an uninterrupted fuel line. However, if a metallic fuel
line is within the 12 inch (305mm) envelope of the surface of the
battery, it shall be shielded dielectrically as required in E-10.7.8.
E-10.7.6 Batteries shall not be installed directly below battery
chargers or inverters.
E-10.7.7 To prevent accidental contact of the ungrounded battery
connection to ground, each battery shall be protected so that metallic
objects cannot come into contact with the ungrounded battery terminal
and uninsulated cell straps. This may be accomplished by means such as;
E-10.7.7.1 covering the ungrounded battery terminal with a boot or
non-conductive shield, or
E-10.7.7.2 installing the battery in a covered battery box, or
E-10.7.7.3 installing the battery in a compartment specially designed
only for the battery(s).
E-10.7.8 Top Terminal Battery - Each metallic fuel line and fuel
system component within 12 inches (305mm) of a battery terminal, and
above the horizontal plane of the battery top surface, as installed,
shall be shielded with dielectric material to protect against
accidental short-circuiting. See Figure 1.
E-10.7.9 Side Terminal Battery - Each metallic fuel line and fuel
system component within 12 inches (305mm) of the terminal side of a
side terminal battery shall be shielded with a dielectric material to
protect against accidental short circuiting. If the battery has side
terminals, the horizontal plane shall be considered to begin below the
side terminals. See Figure 1.
NOTES: 1. Terminal insulation or battery covers do not comply with
this requirement since, during installation or removal of a battery,
these protective devices are usually removed in order to connect the
cables.
2. Any non-conductive material may be used for shielding as long as
it is durable enough to withstand accidental contact by a tool or the
battery terminals during servicing, installation or removal.
E-10.7.10 A vent system or other means shall be provided to permit the
discharge from the boat of hydrogen gas released by the battery. See
ABYC H-2, Ventilation Of Boats Using Gasoline.
E-10.7.11 Battery boxes, whose cover forms a pocket over the battery,
shall be vented at the uppermost portion of the cover.
NOTE TO E-10.7.10 and E-10.7.11: These requirements also apply to
installations of all batteries whether they employ removable vent
caps, non-removable caps, are “sealed” or “maintenance free”
batteries, or have pressure regulated valve vent systems with
immobilized electrolyte (gel batteries).





Paul L wrote:
I found the ABYC Standard E-10.6 Storage Batteries - Installation.
Apparently, it does not require a battery box for any type of battery.

Paul
"Paul L" wrote in message
newsNYZd.8872$Z07.4338@trnddc02...

Does ABYC require that AGM batteries have a battery box?

"Roger Long" wrote in
:

If something does go wrong and one blows up, the acid
impregnated mat in the AGM should be less dangerous and easier to
clean up than the liquid.



Seen it....Acid-soaked glass mat in every nook and cranny. it was
everyplace! What a mess....