On Sun, 2 May 2004 10:55:17 -0400, "Doug Dotson"
wrote:

I guess I had better move my entire breaker panel into the
battery compartment then. All my equipment is protected with breakers.

No, just put a large "main" fuse near your battery and that will
protect in case there is short circut. Have your panel and circut
brakers the way they are now. Needless to say, make sure you have
your fuses in the positive lead.

I have a large 20 A fuse near the battery: it would blow if there was
a major short circut such as my positive cable coming to contact with
ground potential. No need to replace that often, as individual
equipment have 2-5 A fuses in the panel.

Two fuses and several switches will add some resistance, but voltage
drop will not be a problem unless you are running something in
100..150 Watt range.

Other people have already posted warnings, and I would also like to
emphasize that lead-accid batteries have very low internal resistance,
leading to high short circut currents. It is possible to melt a wrench
or other tools if they come to contact with plus and minus terminals.

Almost twenty years ago I was in the Army (Signal Corps), and in field
exercises we run high power HF radios with car battery power before
AC generators were up and running. Could get on the air a few minutes
faster.. Anyway, this one guy managed to short circut a heavy cable
used to jump start cars. Poof, it vanished in a cloud of smoke. That
time we were glad we had gas masks on , that probably saved his
eyesight.

Mike
OH1NZQ

"Mika" wrote in message ...
On Sun, 2 May 2004 10:55:17 -0400, "Doug Dotson"
wrote:

I guess I had better move my entire breaker panel into the
battery compartment then. All my equipment is protected with breakers.

No, just put a large "main" fuse near your battery and that will
protect in case there is short circut.

Of course. I have an 800A T1 fuse close to the battery.

Have your panel and circut
brakers the way they are now.

That would be "breakers".

Needless to say, make sure you have
your fuses in the positive lead.

It is better to have the large fuse in the negative line. It is just as
effective and is safer. Check out www.amplepower.com for
a good justification of this.

I have a large 20 A fuse near the battery: it would blow if there was
a major short circut such as my positive cable coming to contact with
ground potential. No need to replace that often, as individual
equipment have 2-5 A fuses in the panel.

Having the 20A in the negative line will do just as well. Hopefully you
will never have to replace it if the rest of the system is properly
designed.

Two fuses and several switches will add some resistance, but voltage
drop will not be a problem unless you are running something in
100..150 Watt range.

The resistance of fuses and breakers is minor and of no significance
in most cases.

Other people have already posted warnings, and I would also like to
emphasize that lead-accid batteries have very low internal resistance,
leading to high short circut currents. It is possible to melt a wrench
or other tools if they come to contact with plus and minus terminals.

Nothing special about lead-acid. My AGMs and gels will melt a wrench in
pretty short order as well.

Almost twenty years ago I was in the Army (Signal Corps), and in field
exercises we run high power HF radios with car battery power before
AC generators were up and running. Could get on the air a few minutes
faster.. Anyway, this one guy managed to short circut a heavy cable
used to jump start cars. Poof, it vanished in a cloud of smoke. That
time we were glad we had gas masks on , that probably saved his
eyesight.

No kidding. Big batteries are to be respected.

Mike
OH1NZQ

"Doug Dotson" wrote in
:


Of course. I have an 800A T1 fuse close to the battery.

Please change it....if not for the kids, for me. Fuse the battery at 150%
of the maximum normal load on them. Just add up the breakers in the panel,
you'll never draw that much. Make the fuse smaller if the breaker panel is
lightly wired. NO BREAKER PANELS ARE PRIMARY WIRED FOR 800A, unless you're
driving a freighter!

Draw 800A for 60 seconds and I'd bet the batteries will EXPLODE in a
sulfuric acid steam. Wanna try it?


Nothing special about lead-acid. My AGMs and gels will melt a wrench
in pretty short order as well.


Wet cells are "water cooled". AGMs and gels WILL explode in a much SHORTER
time because they are so compact with no chance of any electrolye
circulation. If you short any of them, of course, the acid steam explosion
is nearly instantaneous.

Wanna bet it melts the cheap plastic case?....

Larry

Comments below.

Doug
s/v Callista

"Larry W4CSC" wrote in message
...
"Doug Dotson" wrote in
:


Of course. I have an 800A T1 fuse close to the battery.

Please change it....if not for the kids, for me. Fuse the battery at 150%
of the maximum normal load on them. Just add up the breakers in the
panel,
you'll never draw that much. Make the fuse smaller if the breaker panel
is
lightly wired. NO BREAKER PANELS ARE PRIMARY WIRED FOR 800A, unless
you're
driving a freighter!

Draw 800A for 60 seconds and I'd bet the batteries will EXPLODE in a
sulfuric acid steam. Wanna try it?

I'm tired. It's a 200A, oops! Sorry.


Nothing special about lead-acid. My AGMs and gels will melt a wrench
in pretty short order as well.


Wet cells are "water cooled". AGMs and gels WILL explode in a much
SHORTER
time because they are so compact with no chance of any electrolye
circulation. If you short any of them, of course, the acid steam
explosion
is nearly instantaneous.

I think that is why we have the fuse. So that point is moot. I doubt if the
electrolyte circulation in an enclosed space will buy much additional time,
maybe a few seconds. I wonder why most military vehicles including all
aircraft switched to AGM years ago if their failure mode is so
catastrophic?

Wanna bet it melts the cheap plastic case?....

I can't tell any difference between the quality of the case in my Trojan
T-105s I had in my old boat vs the case of my 8D AGMs I have now.
I do think the maroon T-105s were much more attractive than the
battleship grey AGMs though

Larry

On Sun, 2 May 2004 21:36:53 -0400, "Doug Dotson"
wrote:

Have your panel and circut
brakers the way they are now.

That would be "breakers".


No wonder I used to get just B´s with all these typos

Mike

That would be "B" for "Breakers".

"Mika" wrote in message ...
On Sun, 2 May 2004 21:36:53 -0400, "Doug Dotson"
wrote:

Have your panel and circut
brakers the way they are now.

That would be "breakers".


No wonder I used to get just B´s with all these typos

Mike