"Flying Pig" wrote in message
...
I suspect that this has already been discussed, but since I don't have
access to the archives, I beg your indulgence...

We have new, L16H batteries in our 880AH house bank, flooded cell. In a
perfect world to make them last longest, I know that they'd never be
allowed to drop below 100% capacity - but then, what's the point of
having a battery?

I also know that running them down to 20% on a regular basis will make
for a short life span.

So, the question (well, maybe two) is:

What is the recommended, real-world cycle? That is, how low do you
take your flooded batteries on a regular basis? Related, is there a
readily available source for information on the numbers of cycles to a
given percentage of discharge in a battery life span? I.e., 500
cycles to 50% and back to 100% but only 100 cycles to 20% and up to
75%, or the like (recognizing that these numbers have no relation to
any battery made)?

Second, what do those of you with flooded cells, not connected to the
shore power all the time (that is, full-time cruisers or rarely
connected to the utility-based power cord) have as a practice? What
charge regime, and how, do you observe? Never below X%, seldom above
Y%/Always more than Y% of capacity?

We have a variety of charging sources and differing loads which makes
for days when we may see close to 50%, and days when it never leaves
"full" - and since we can't "force" "full" reasonably, we want to make
sure we're not unreasonably asking for our batteries performance.

Knowledgeable assistance appreciated, and your practice, whether
empirical or just "is" would also be appreciated.

Thanks.

L8R

Skip (Gundlach) and crew, lying Lucaya, over (what else??) wifi among
the 14 available open sites we can see

Morgan 461 #2 St. Thomas USVI
SV Flying Pig KI4MPC
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"And then again, when you sit at the helm of your little ship on a
clear
night, and gaze at the countless stars overhead, and realize that you
are
quite alone on a wide, wide sea, it is apt to occur to you that in the
general scheme of things you are merely an insignificant speck on the
surface of the ocean; and are not nearly so important or as
self-sufficient
as you thought you were. Which is an exceedingly wholesome thought,
and one
that may effect a permanent change in your deportment that will be
greatly
appreciated by your friends."- James S. Pitkin





You have a big problem, Skippy. The problem is you are trying to run what
amounts to the average size house ashore on batteries. Considering your
total power usage you need a battery bank of at least 20 (yes, I said
TWENTY) of those Trojan deep cycle six-volt batteries. Then you need a
separate battery bank of at least 2 heavy duty cranking batteries for your
starter.

You should do either of three things.

1) continue to be an energy hog and plan on running your diesel with heavy
duty alternator for at least 8 hours a day to properly charge the above
suggested battery bank.
2) invest in an 8KW diesel variable output genset and run it 24/7 and reduce
the size of the suggested battery bank by a factor of five.
3) get rid of 80% of the crap in your boat that runs on electricity that you
don't need anyway and start acting like a sensible cruiser and have a
battery bank of 4 Trojans plus two starter batteries and charge them using
photovoltaics (400 watts worth) plus wind generator and stick to using no
more electricity per day than these input.



Wilbur Hubbard