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Old 04-06-2017, 13:21   #1
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Do I really need a new battery already?!?

My boat was put into service Oct 15, I brought it from where it was bought to where is was to be winterized. Batteries were disconnected for that winter. Boat was used about 25 days last year, nothing very heavy, all day sailing. I put 2 280 solar panels on it. Left battery connected through the winter.

Getting boat ready for service this past weekend, and noticed last night (so no solar), battery was reading 12.4 with some cabin lights on(all led), 12.5V when I went to bed. I was kind of freaked by this, I am not sure if this seems low, so I got out the hygrometer, and tested 9 of the 18 cells, most read between 1225 (which is the upper end of 'fair' on my device) to about 1250). So this should be OK.

This morning, with the sun out, V is 13.7, which on my MPPT controller is float. The batteries should be fully charged, I ran both engines for about 2 hours yesterday, I have 2 80 A alternators going into a 420 Ah bank. The controllers have been reading float while I was doing work on the hard during the past month.

I can't find a SOC table for my exide batteries, I remember in some post on this forum seeing one. (there are probably lots). did a search, way too many posts. But normally, I think 12.8 is 100% and 12.5 is like 60%? I did not shut the battery switch and measure across the terminals, which I should have done, so there was some load, I should have read this open circuit I think?Can someone post this table, and let me know if I my batteries need replacing already.
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Old 04-06-2017, 13:43   #2
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Re: Do I really need a new battery already?!?

What line/model battery?

One sentence says they were disconnected for the winter, another says connected - to solar or mains?

What solar controller, and what is the setting for transition to float?

Goal should be to get to true full 100% as quickly as possible. Alternators no matter how large won't do that in a couple hours when the bank's depleted, they're fine to get through Bulk, well into Absorb say 80-85% full, but then the low-amp "long tail" will likely take at least another 6 hours on solar or shore power.

Voltage is not an accurate measure of SoC, loads, resting time, too many variables.

Hydrometer is, but ideal would be a SmartGauge or shunt-based coulomb-counter.
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Old 04-06-2017, 14:00   #3
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Re: Do I really need a new battery already?!?

I can't find anything from sources I trust that Exide makes *any* batteries considered true deep cycle, they all seem to be "dual purpose" starters.

If that's the case, get the knowledge and infrastructure in place to take ideal care of them, and you may get some more useful life out of them, but likely not the many years you will from the next higher-quality bank.

http://www.pbase.com/mainecruising/deep_cycle_battery
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Old 04-06-2017, 14:09   #4
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Re: Do I really need a new battery already?!?

Thanks for the quick reply and sorry for the confusion.

1st winter disconnected. this past winter, on solar.

MPPT float at 13.7, absorb at 14.4

http://eco-worthy.com/catalog/download/20AMPPT.pdf

If the bank was 50% depleted, 2 hours of motoring with 2 alternators , plus solar, would put back lots. I am worried that the bank's maximum capacity when I fully charge it is possibly somewhat depleted, more so than what it should be for its age. Hygrometer gave me readings, just not sure what they should be vs. what they are.
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Old 04-06-2017, 17:27   #5
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Re: Do I really need a new battery already?!?

1. Do you know the true age of the batteries. Your original post makes it sound like they were on the boat when you bought it.

2. Suggest you get Niger Caldwell's book on boat electrical systems. Flooded cells all have pretty similar specs, and Nigel covers battery, testing and age issues very well.
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Old 04-06-2017, 20:07   #6
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Re: Do I really need a new battery already?!?

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If the bank was 50% depleted, 2 hours of motoring with 2 alternators , plus solar, would put back lots.
Yes lots, but for longevity the goal is to get back to 100% full ideally every cycle. And never below 50%.

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I am worried that the bank's maximum capacity when I fully charge it is possibly somewhat depleted, more so than what it should be for its age.
Well that happens with all banks, just more slowly if you **know** you're doing the above.

Your hydrometer (not hygrometer) can tell you, once you get the specs, ideally from mfg tech support. Get a good 80-100A charger on them overnight with no loads, keep pumping Bulk level voltage in until current drops right down to below say 6A.

Maybe do an Equalization routine on them next cycle, as per mfg protocol, probably should be doing that monthly.

Then another cycle down & back up as above, keep checking SG, keep notes, and try to set your usual charge sources to hit those levels routinely.

A SmartGauge is of course much easier, since it's realtime and automated.

Once your routine is solid aybe you can get another good hundred cycles out of what you've got now.

And if not, you can be confident in investing next time in a RE line of a quality brand like U.S. Battery, Trojan, East Penn, or even Rolls/Surrette.

Or more cheaply, with pairs of 6v GC2s.

12v is more a roll of the dice with other brands.
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Old 04-06-2017, 20:09   #7
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Re: Do I really need a new battery already?!?

Fluid on top of the batteries might indicate overcharging. Solar controllers to the left look like the cheap Chinese ones known to be quite unreliable. Why are there black and red cables to the same terminal??? Something ain't right in Beantown.
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Old 05-06-2017, 04:53   #8
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Re: Do I really need a new battery already?!?

Before you do anything you need to start by fully charging your batteries. By that I mean charge them till they accept less than 0.5% of rated amp-hours (amps = <0.5% amp-hours) at absorption voltage of at least 14.6V. Then consider going an equalization at 15.2V till the specific gravity of the batteries stop increasing. That is going to take all day probably.

Then you can do some discharge measurements.

BTW - your solar being in floats only means your solar was in float. It means normally about your state of charge. Two hours of engine running will not fully charge a set of batteries (unless they were at at 98% to start with with).
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Old 05-06-2017, 05:24   #9
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Re: Do I really need a new battery already?!?

If your batteries have not been at rest -- meaning disconnected from any charging or discharging source -- for at least 8-10 hours, then a voltage reading is nothing more than a very rough ballpark estimate of state of charge. And even then, it is not as good a measure as an accurate hydrometer reading. I think you're worried about nothing.

If you are really concerned, get the batteries fully charged (you don't have to do an equalization charge), disconnect them completely, let them rest overnight, and then check the voltage with a good, accurate voltmeter. My guess is that they are fine.
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Old 05-06-2017, 06:31   #10
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Re: Do I really need a new battery already?!?

Quote:
Originally Posted by jamhass View Post
1. Do you know the true age of the batteries. Your original post makes it sound like they were on the boat when you bought it.

2. Suggest you get Niger Caldwell's book on boat electrical systems. Flooded cells all have pretty similar specs, and Nigel covers battery, testing and age issues very well.
Boat was purchased brand new. Assuming batteries are close to that, so 2 years old. Batteries were not connected to boat until Oct 15, then disconnected Nov 15, reconnected May 16, solar installed.

Have Niger Caldwell's book. Have a degree in electrical engineering, but mostly on mathematical analysis of signals. But have more than a basic understanding of electricity.

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Before you do anything you need to start by fully charging your batteries. By that I mean charge them till they accept less than 0.5% of rated amp-hours (amps = <0.5% amp-hours) at absorption voltage of at least 14.6V. Then consider going an equalization at 15.2V till the specific gravity of the batteries stop increasing. That is going to take all day probably.

Then you can do some discharge measurements.

BTW - your solar being in floats only means your solar was in float. It means normally about your state of charge. Two hours of engine running will not fully charge a set of batteries (unless they were at at 98% to start with with).
I am going to assume, and that is wrong of me, but the boat wasn't used for 6 months, from Nov 16 till now. It has 560 w of solar. I know winter isn't the best time, but I would believe that after 180 days, the solar would have charged the batteries. After that, for the last month, while prepping the boat, I have had it plugged in for about 24 hours with a 40A charger. Since it was put in the water, engines have been run about 6 hours, with 2 80A alternators. All during this time, there has been no load except 2 hours of instruments.

I believe that my batteries are fully charged, or should!

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Originally Posted by denverd0n View Post
If your batteries have not been at rest -- meaning disconnected from any charging or discharging source -- for at least 8-10 hours, then a voltage reading is nothing more than a very rough ballpark estimate of state of charge. And even then, it is not as good a measure as an accurate hydrometer reading. I think you're worried about nothing.

If you are really concerned, get the batteries fully charged (you don't have to do an equalization charge), disconnect them completely, let them rest overnight, and then check the voltage with a good, accurate voltmeter. My guess is that they are fine.
This I will do!

Appreciate everyone's input.
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Old 05-06-2017, 06:53   #11
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Re: Do I really need a new battery already?!?

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Boat was purchased brand new. Assuming batteries are close to that, so 2 years old. Batteries were not connected to boat until Oct 15, then disconnected Nov 15, reconnected May 16, solar installed.
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I am going to assume, and that is wrong of me, but the boat wasn't used for 6 months, from Nov 16 till now.
OK, the biggest false assumption is that the boat builders have the knowledge and motivation to optimize their delivered electrical setup.

The bundled batteries are less than ideal. Check their mfg date, sitting in supply chain storage in itself reduces lifetime.

Also please specify the solar controller and shore charger you're using.

Even if perfectly good, they may well have been installed left at their defaults and/or configured wrong.

Such long periods of disconnected storage at less than 100% full and no trickle/float against self-discharge would definitely have impacted longevity.

Quote:
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I know winter isn't the best time, but I would believe that after 180 days, the solar would have charged the batteries. After that, for the last month, while prepping the boat, I have had it plugged in for about 24 hours with a 40A charger. Since it was put in the water, engines have been run about 6 hours, with 2 80A alternators. All during this time, there has been no load except 2 hours of instruments.
It is entirely possible that unmonitored, substandard and/or misconfigured infrastructure gear will fail to properly care for a bank, or even actively damage it.

You need to **verify** their charging algorithms are performing properly and that the resulting battery SoC cycling are as to be expected.
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Old 05-06-2017, 07:32   #12
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Re: Do I really need a new battery already?!?

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I have had it plugged in for about 24 hours with a 40A charger. Since it was put in the water, engines have been run about 6 hours, with 2 80A alternators. .
My 100 amp battery charger will NEVER fully charge my 440AH house bank!!!! It will go into float with there still being -25AH. Maybe in a few days the battery monitor will say the the batteries are charged, but they aren't really.

I have a lot of experience watching my batteries charge; if I started in the morning at -125AH and motored for 6 hours the batteries will NOT be fully charged. It wouldn't matter how many or how big the alternators are as the batteries are only accepting a few amps.

You need to stop assuming and do the full charge and equalization as I suggested. Maybe you need new batteries, but why guess instead of doing the full charge/equalization to find out?
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Old 05-06-2017, 07:59   #13
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Re: Do I really need a new battery already?!?

Not sure what you mean by fully charge. If I have my solar/plug in via battery charger/alternator all working, that is the only way I am going to charge the battery. Are you saying I can't fully charge it this way? If not how do I do this.

Further, how do I do an equalization?
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Old 05-06-2017, 08:54   #14
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Re: Do I really need a new battery already?!?

First of course you need your hydrometer, and instruments that measure volts and amps.
Quote:
Originally Posted by jbinbi View Post
Not sure what you mean by fully charge.
You've already been told:
Quote:
Originally Posted by sailorboy1 View Post
Before you do anything you need to start by fully charging your batteries. By that I mean charge them till they accept less than 0.5% of rated amp-hours
Quote:
Originally Posted by john61ct View Post
Your hydrometer (not hygrometer) can tell you, once you get the specs, ideally from mfg tech support. Get a good 80-100A charger on them overnight with no loads, keep pumping Bulk level voltage in until current drops right down to below say 6A.
Contact the battery mfg for the actual specs, what they consider ideal charging algorithm.
As an engineer, you should have no problem informing yourself of the details on these pretty basic issues.
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Old 05-06-2017, 09:11   #15
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Re: Do I really need a new battery already?!?

I recommend that you read Maine Sail's articles on batteries and battery charging.

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