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post #1 of 4 Old 12-18-2016 Thread Starter
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Battery Woes...

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

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post #2 of 4 Old 12-18-2016
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Re: Battery Woes...

I don't think they are toast at this point, at least looking the SG readings. I would try an extended charge without going through a regulator and see what happens.

Good luck,

Gary
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post #3 of 4 Old 12-18-2016
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Re: Battery Woes...

You don't mention your charging voltages except for the one mention of 14.1V. These batteries should be charged through absorption at 14.7-14.8V. If you have been charging at 14.1V, then it is possible they are sulfated and need longer equalization to mitigate.

You also don't mention what "fully charged" means. Does this mean that the batteries have sat at 14.8V for several hours and the current has tapered down to <10 amps or so? If not, then full charge was never met.

We also have a Trimetric monitor and while good, it is tricky to set it up so that the amp-hour counter is accurate. There is no Peukart adjustment, only a charge efficiency adjustment, and getting this set to match the bank's usage profile isn't easy. Thus, it quickly becomes inaccurate and 0Ah can be meaningless. The only way to keep it mostly accurate is to fully charge the batteries every so often until they no longer accept current at 14.8V and then rezero it.

Things get even worse with this monitor if you set it to automatically rezero itself when it thinks the batteries are full. If yours is set that way and you have used it as a charging guide, then I guarantee you have been walking down your batteries for the past 30 months.

As an aside, we now have lithium batteries, which have little Peukert effect and unity charge efficiency, and this monitor works brilliantly with them. Its Ah counter walks down 1-2Ah per 3-4 weeks, and rarely needs to be reset.

The cells may be knackered or they may just need to be equalized for a longer period. IMO 15.2V is too low - I would be doing it at 16-16.2V. Remember, you first need to get these batteries to a full charge before equalizing. 14.7V with little current acceptance.

It wasn't clear to me how these batteries are installed. Are they two banks of serial pairs or a single bank of 4 in parallel/serial? And if separate banks, are you charging them separately or combined?

If you were equalizing at 15.2V, then one of the batteries overshot this voltage and the other three are well below it. This leads me to think that you never had these batteries charged before equalizing, and may have a charger problem also.

Mark

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post #4 of 4 Old 12-19-2016
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Re: Battery Woes...

Quote:
Originally Posted by skipgundlach View Post
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.
Were the batteries ever commission charged? For batteries that are to be wired series or series>parallel I wire them in parallel then charge to 7.4V and about 0.5% or less of tail current base on the 20 hour capacity. The batteries are now "balanced" and can now be wired series>parallel. Batteries wired in series will have a very tough time "self balancing". If they are not in good balance one battery can easily become over charged while the other gets chronically undercharged....

Quote:
Originally Posted by skipgundlach View Post
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.
I am assuming by the term "charge" you are referring to bulk-charging In order to "charge" (fully charge) L-16's is going to take upwards of 8-12 hours with good equipment and correct voltages, and even longer with sub-par equipment.

Quote:
Originally Posted by skipgundlach View Post
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).
I suspect you are putting WAY too much trust in your Ah counter. When was the last time you conducted a 20 hour capacity test and re-programmed the Trimetric for the banks actual capacity?

How are you defining "full"? Until your bank is accepting approx 0.5% of Ah capacity in charge current, at 14.7V to 14.8V, its simply not full. Many battery monitors attempt to re-set at 2% but again this is not a full battery and you're leaving sulfate on the plates.

Keeping Your Battery Monitor More Accurate (LINK)

Quote:
Originally Posted by skipgundlach View Post
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.
GIGO data (garbage in>garbage out) is simply unacceptable data to use. Unless your Trimetric has been painstakingly programmed and reset to 100% SOC when the batteries are actually at 100% SOC this data can be extremely misleading. The only reliable & repeatable way to determine full, on a cruising boat, is to hold absorption voltage (14.7V to 14.8V) until the net accepted current falls to approx 0.5% of bank Ah capacity or less.

Quote:
Originally Posted by skipgundlach View Post
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).
If the battery is left sulfated from chronic under charging it is still being worked hard. Shallow cycles are certainly much better for it, less sulfation created during discharge, but full charges must be attained as often as is humanly possible otherwise you will continually "walk down" the usable capacity due to PSOC (partial state of charge) use.. Low charging voltages, which can be a volt sensing issue, inadequate voltage regulation settings or alternators that reduce voltage as they heat up, and inadequate absorption duration are the two biggest hurdles most boaters deal with.

If you are only cycling to 70% SOC then you are also playing in the most charge inefficient range of the battery so your absorption voltage duration is absolutely critical in order to reach 100% SOC..

You will need to figure the correct duration out for your use and bank via SG or tail current @ absorption voltage. For a bank like that it will typically require 4-6+ hours of absorption, once absorption voltage has been attained, before float kicks in. If your charge sources do not allow an adjustment of the absorption duration, and far too many are absurdly short 1 hour or 2 hour egg-timers, then you'll want better charge equipment. For a live aboard cruiser solar simply disable float or set it to at least 14.3V with absorption being 14.7V+. If you leave the boat for extended periods re-set the float voltage.

Quote:
Originally Posted by skipgundlach View Post
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.
Based on what you've given us, it's pretty safe to say your bank has nowhere near the capacity that you have programmed into the monitor. Like many boaters with Ah counters you've put far too much trust in the Ah counter predictiing SOC and too little attention to actual battery voltage..

This is not just for you but for all boaters.

DO NOT REGULARLY DISCHARGE BELOW 12.2V EVEN UNDER LIVE AVERAGE HOUSE LOADS

Sure on a long passage it is okay to dip towards 11.7V, but if this basic premise had been followed you'd have very quickly realized the bank was walking down in capacity and the Trimetric was fooling you. A bottom voltage is the best thing any boater with an Ah counter can incorporate. You can even set an alarm for 12.2V...

Quote:
Originally Posted by skipgundlach View Post
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).
Three hours of absorption is not full and 14.1V spells murder for L-16's.....

Quote:
Originally Posted by skipgundlach View Post
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...
Not really that weird they have been under charged, likely not properly commission charged, and they have become out of balance or started life out of balance and this just got worse. This could also be due to bank interconnect wiring or trying to alternate two house banks instead of one large contiguous bank... I also have no idea what you mean by "The banks/pairs are 1/4 and 2/3,"?

Quote:
Originally Posted by skipgundlach View Post
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.**
You had one out of balance battery being pushed to 8V, and this is the equivalent of 16V, while another battery was at 6.68V which is the equivalent of 13.36V.. The bank is severely out of balance.

Put another way you have two batteries in series that have become out of balance and they look like this during charging.

Battery #1 = 8V
Battery #2 = 6.68V
Charger See's = 14.68V


Battery #1 - Being grossly over charged
Battery #2 - Being grossly under charged

Quote:
Originally Posted by skipgundlach View Post
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.
Sounds like chronic under charging & sulfation...



Quote:
Originally Posted by skipgundlach View Post
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?
I have an idea yes but we really need more information on equipment, wiring, bank use, bank wiring, alternator model and amp rating, Blue Sky settings etc....

The batteries may be toast but may recover to a suitable & still usable smaller size too. Best to conduct a 20 hour test to see where they stand. 370Ah / 20 = 18.5A constant load for a capacity test to a 10.5V cut off. If the battery only runs a fraction of 20 hours this will be the percentage in-hours, of the 20 hour rating. For example if the battery only runs for 10 hours to 10.5V at 18.5A and at 75-80F, then the bank is at 50% of its rated capacity and is pretty much done for. If it runs for 16 hours you're at 80% of rating and the bank is starting to approach the danger zone...

______
-Maine Sail / CS-36T


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Last edited by Maine Sail; 09-01-2017 at 06:18 PM.
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