LETTERS TO THE
EDITOR
course, is also important, and the
guidelines set forth in ABYC Standard
E- 10, “Storage Batteries,” and
Standard E- 11, “AC and DC
Electrical Systems,” should be closely
followed. The cold-cranking amps
contained in your sizable bank of
12 Group 31 AGM batteries is over
10,000. That’s substantial, indeed,
should a short circuit occur. Therefore,
I advise you, regardless of the
configuration, to carefully and
conscientiously route each cable
to prevent all possibility of short-circuiting and to properly over-current
protect the output using a fuse or
circuit breaker that is properly sized
for the cable gauge.
The commonly accepted
and appropriate arrangement for
paralleled batteries is the first choice
you mentioned: connecting each
battery to the other essentially in
a row. It’s important, however, that
supply (out) cables, the ones leading
to the boat’s electrical panel, be
attached to this bank at opposite
ends (not by connecting to the positive
and negative terminals of the same
battery). This ensures that the batteries
are drawn upon and charged evenly.
The charging circuits should be
attached to the bank in the same
manner; however, they should be
attached to the terminals opposite
the supply connections (i.e., positive
cables for supply and charging should
be connected at opposite ends of the
bank, and likewise with negative
cables). This approach allows the
batteries to act as a buffer of sorts,
reducing voltage spikes and dips.
You could also split this
arrangement into two banks of six
batteries each and equip them with
isolation switches so that if one
battery failed, it could be isolated
(along with half of the overall bank).
This would enable you to continue to
use the remainder of the batteries. If
you take this approach, however, you
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