Battery Woes...

Well, Dang!

I installed new Deka L16 batteries (4x370AH, bank 740AH in April 2014. They
appear to be at the end of their lives at ~30 months in. We have been
diligent in keeping them watered with distilled water, and have battery
saver caps to minimize water loss.

We charge with a Honda 2000 connected to our shore power, which feeds a
Xantrex 70A/1500W temperature-probed inverter-charger. That has a design
issue which makes it not float out well, so we transfer to our 40A
stand-alone charger for the last of it.

We monitor everything through a Trimetric battery monitor. We fully charge
once a week or more often, through, also, our 370W solar feeding a Blue Sky
6024H MPPT controller, and our KISS wind generator, and equalize once a
month (using the Honda and the Xantrex).

When we're motoring, our alternator keeps up with it, but doesn't seem to
have a good control/regulator; even though the output shows low net incoming
amps after a long while, our cumulative AH shows positive values (20-40AH
typical) which, of course, goes away the moment the engine is off, but our
battery is certainly fully charged, if not equalized.

All charge sources are fed to a single buss protected by a 500A in-line
fuse. Our typical charge is at 25-30% discharged, so the battery doesn't
work very hard. It has been to 45% discharged a few times, and once to 55%
(Hurricane Matthew, with the KISS disabled, and not much sun in the 4 days
we were off the boat).

In the last few weeks, I have gotten up in the morning to ~220AH used - less
than 30% discharged - and found voltage at 11.3. Not good at all - whassup?
So, I've been wrestling, with no solutions or even clues.

We've been fully charging about every 2-3 days of late, due to work we've
been doing which requires the Honda, and yesterday I fully charged (one hour
at 14.1V or better) and equalized (2 hours at 15.2V or better), and
immediately read the batteries with a temperature-compensated hydrometer and
also our voltmeter, at the end, while still charging, the individual battery
voltages (ya, I know - they weren't disconnected).

The 4 had divergent readings at the end of the equalization cycle: 8.0,
7.3, 7.33 and 6.68 volts. The banks/pairs are 1/4 and 2/3, and,
cumulatively, the banks had the same readings, but with very different
single readings. I suppose that could be laid to the fact that I couldn't
effectively disconnect them, but it's still pretty weird...

Temperatures were very different between banks one and two (read down each
water-fill hole; I've averaged the 3 readings per battery) immediately after
equalization:75, 98, 100, 73F - from which I gather/intuit that bank one
(1/4) got much less amperage, somehow, or there was some problem in bank 2.

Specific gravities were lousy. All the cells read in about the same range
per battery, with bank 1 faring much better than bank 2: Bank one averaged
about 1.227 and bank two, temp compensated for 8-10 added, averaged 1.220 -
but that included one cell in 2/3 - at both ends; cells 5-8 read 1.220, but
had 1.235 and 1.260 in cells 4 and 9.

None of them was better than fair, and many of the cells were in the edge of
the "charge" range - immediately after equalizing.

So, clearly, something is amiss.

Beyond just bad luck, are there any ideas of how this might have occurred,
given the above? And, my presumption, are these batteries toast?

Thanks.

L8R

Skip

Morgan 461 #2
SV Flying Pig KI4MPC
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Practical Sailor just had an article about battery control systems.
If I understand (I don't have one) the system needs to know the AH
capacity of the batteries. If you don't remeasure that often enought
(yearly?) and have thus too high an estimate, the system can degrade
the batteries by running them too flat.

I haven't a clue but am continually amazed at the complexity of your
boat. It strikes me that all these electrical systems will fail time and
time again draining a bit of the fun from cruising due to you always
needing to diagnose and then address - often at brutal expense
whatever's failed this day.

I went from an icebox / shore power only to a boat with shore power
HVAC, refrigerator / freezer and hot pressure water made hot by an
engine fired heat exchanger. The hot water after a few days at sea was
incredible but I am unsure if I'd do such complexity again. Even my
relatively simply rig was always subject to some failure or maintenance
demand. I got tired of it very quickly.

-paul

My experience is with highway vehicles, not boats, but your description
sounds like a low level of corrosion in the wiring to me.

I'm guessing that there is a layer of oxidation in several different
connections that's too thin to see, but thick enough to create a slight
resistance and screw up the voltages.

I suggest that you clean ALL of your battery posts and clamps until they
shine, whether they need it or not. Then go to the other end of the
cables and clean them up where they mount to the electrical system.

I'm thinking that if you go through a normal cycle of use after all of
the connections are shiny and tight, the voltages will look better at the
end of a charge.

On Sun, 18 Dec 2016 10:43:57 -0500, Flying Pig wrote:



We've been fully charging about every 2-3 days of late, due to work
we've been doing which requires the Honda, and yesterday I fully charged
(one hour at 14.1V or better) and equalized (2 hours at 15.2V or
better), and immediately read the batteries with a
temperature-compensated hydrometer and also our voltmeter, at the end,
while still charging, the individual battery voltages (ya, I know - they
weren't disconnected).

The 4 had divergent readings at the end of the equalization cycle: 8.0,
7.3, 7.33 and 6.68 volts. The banks/pairs are 1/4 and 2/3, and,
cumulatively, the banks had the same readings, but with very different
single readings. I suppose that could be laid to the fact that I
couldn't effectively disconnect them, but it's still pretty weird...

Temperatures were very different between banks one and two (read down
each water-fill hole; I've averaged the 3 readings per battery)
immediately after equalization:75, 98, 100, 73F - from which I
gather/intuit that bank one (1/4) got much less amperage, somehow, or
there was some problem in bank 2.