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Old 03-22-2014, 10:28 AM   #21
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After charging and a rest, I would disconnect all 4 battery + leads and read the voltage of each battery individually with a DVM. I'm thinking at least one battery is dragging down the bank. If so, try the bank with only the 3 best batteries connected and the monitor set to 315 AH.
The "bad" battery may not be completely bad at all. It just may have a higher internal resistance to the other 3 in parallel and not be getting fully charged. It might work fine in a single battery application like a generator start battery for several years. Given their cost, I hate to toss an AGM unless its truely dead.
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Old 03-22-2014, 12:22 PM   #22
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It's been 6 years since I installed mine; I was looking through the manual to my Magnum and they want you to have the batteries fully charged (at least according to your charger) before hooking up the monitor. So perhaps the monitor is out of whack due to being initially hooked up to not fully charged batteries? Probably worth a call to Victron on Monday to get their advice.
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Old 03-22-2014, 06:25 PM   #23
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Bummer to hear you're having these problems.
We've all been there.

Two things i noticed in my five months of data and making scatter diagrams of voltage versus Amp-hours
1. As everyone as said, you really need to rest your batteries to get a decent voltage reading, now, what does that mean, the longer the better, but just turn everything off and in 15 minutes, you'll see a difference (though as other's have said, it's still not totally accurate, as my graphs have shown me)
2. If you were still putting 20 amps into your batteries, then they are NOT fully charged. You need to get them fully charged before you make any decisions. The problem is the charge rate is not linear and flattens out greatly as the batteries get up to full. THerefore it may take many hours to get to full charge. I usually don't run gen to get to full charge as it will take forever. i may go from 60% up to 80 though.
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Old 03-22-2014, 08:56 PM   #24
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Where does a SOC meter get info on a battery bank that is no where's near new and only 50-75% of it's "rated" capacity?
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Old 03-22-2014, 10:24 PM   #25
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Reread your monitor installation book. On my magnum under setup I was required to input the total amp hours of my battery bank. This would allow the charger to input maximum required charge for the bank and correctly show SOC.
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Old 03-23-2014, 03:42 AM   #26
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Where does a SOC meter get info on a battery bank that is no where's near new and only 50-75% of it's "rated" capacity?
That will become evident to the user.

If you tell the SOC meter that the bank is x amp hours and it then calculates that you are at say 50% but your battery voltage is low then you'll know that your battery bank has lost some of its capacity.
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Old 03-23-2014, 06:48 AM   #27
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Before I installed the monitor the batteries were fully charged. They had been on the battery charger at the dock for a week or so. I think Kevin may be right. I inputted 420 ah as the size of the battery bank and even though it had been on the charger for some time the voltage was less than a new bank would have.

I will note the voltage after a couple of days on the charger.
But I think High Wire may be right, I need to pull the batteries and have them tested.

And Richard is right the batteries were not fully charged yesterday because the charger was putting out 20 amps. That was after 2 hours of genny run time and why I need a bigger charger.

But psneeld asks a good question, if a battery bank is not new is a battery monitor giving good info? A call to Victron is in order.
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Old 03-23-2014, 07:41 AM   #28
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Before I installed the monitor the batteries were fully charged. They had been on the battery charger at the dock for a week or so. I think Kevin may be right. I inputted 420 ah as the size of the battery bank and even though it had been on the charger for some time the voltage was less than a new bank would have.

I will note the voltage after a couple of days on the charger.
But I think High Wire may be right, I need to pull the batteries and have them tested.

And Richard is right the batteries were not fully charged yesterday because the charger was putting out 20 amps. That was after 2 hours of genny run time and why I need a bigger charger.

But psneeld asks a good question, if a battery bank is not new is a battery monitor giving good info? A call to Victron is in order.

A friend of mine has a sailboat with the typical setup many of you have....large charger inverter, several different banks to run house, engine, electric winches/windlass ...and a SOC. Because I never had a chance to go through everything with him and know the health of the batteries...and his lack of thorough electrical system knowledge...the SOC was never even in the ballpark.

This is one reason I have shied away from them as is that I have a good understanding of my system and the current draws being placed on it...sure I'm no where's near the 5-10% accuracy range of a SOC, but based on my battery life over the years...which is about the same as everyone else's...my guesstimates must be close enough.

At least as good as most people's "guess" of what their batteries "actual" capacity is versus what the factory specs say. I am leaning toward trying one as I think ultimately I am going to try to outfit my boat to be as close to 12V only as I can. Electric charge costs at many marina's is becoming outrageous.
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Old 03-23-2014, 09:49 AM   #29
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I am not particularly good at articulating this, but at the risk of introducing more confusion, here goes.

The modern battery monitors take into account all the same factors, and more (such as using the Peukert formula to a certain degree), that one would use to judge a battery's "age" and condition. This is primarily done while evaluating the charge cycle, reevaluating the actual charge efficiency every time full charge is reached. Typically, they determine a full charge has been reached when all three parameters are met:

1. The charging voltage has stabilized over a period of time.
2. The charging current has decreased to a low percentage of the amp- hour capacity – normally less than 2%.
3. The amp-hours that were removed from the battery are within 1% of fully being returned.

They evaluate what it took to get to get to these thresholds and how long, what the voltage reading vs amp hours consumed, and rate of discharge. So if you tell it that it is looking at a 420 amp hour battery, but the thing isn't acting like one, it will with readjust the charge efficiency factor as the battery dies. I reached the point on my old 410AH inverter bank where SOC was 50% after 100 amp hours were removed, and it was taking forever to get them to full charge.

One factor that the thread has ignored, I think, and may or may not come into play with Tim's situation, is that the rate of discharge affects capacity fairly dramatically. A 100ah (using the 20 hour standard) rated battery's capacity is based on a 5 amps discharge rate. However, at a 25 amp discharge rate has about a 50ah capacity (2 hours) So it is for practical purposes "spent" at 1 hour.(as you can see it is not a linear relationship) So a good SOC meter also takes this into account over time.

The Magnum, Victron (just skimmed it) and Trimetric manuals all discuss these factors to varying degrees, and the different devices seem to address them in slightly different ways.

Anyway, some food for thought, flames and comments welcome!
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Old 03-23-2014, 12:48 PM   #30
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I am not particularly good at articulating this, but at the risk of introducing more confusion, here goes.

The modern battery monitors take into account all the same factors, and more (such as using the Peukert formula to a certain degree), that one would use to judge a battery's "age" and condition. This is primarily done while evaluating the charge cycle, reevaluating the actual charge efficiency every time full charge is reached. Typically, they determine a full charge has been reached when all three parameters are met:

1. The charging voltage has stabilized over a period of time.
2. The charging current has decreased to a low percentage of the amp- hour capacity normally less than 2%.
3. The amp-hours that were removed from the battery are within 1% of fully being returned.

They evaluate what it took to get to get to these thresholds and how long, what the voltage reading vs amp hours consumed, and rate of discharge. So if you tell it that it is looking at a 420 amp hour battery, but the thing isn't acting like one, it will with readjust the charge efficiency factor as the battery dies. I reached the point on my old 410AH inverter bank where SOC was 50% after 100 amp hours were removed, and it was taking forever to get them to full charge.

One factor that the thread has ignored, I think, and may or may not come into play with Tim's situation, is that the rate of discharge affects capacity fairly dramatically. A 100ah (using the 20 hour standard) rated battery's capacity is based on a 5 amps discharge rate. However, at a 25 amp discharge rate has about a 50ah capacity (2 hours) So it is for practical purposes "spent" at 1 hour.(as you can see it is not a linear relationship) So a good SOC meter also takes this into account over time.

The Magnum, Victron (just skimmed it) and Trimetric manuals all discuss these factors to varying degrees, and the different devices seem to address them in slightly different ways.

Anyway, some food for thought, flames and comments welcome!
That sounds like a good analysis based on your reading in depth the manual.

I never did that, so thanks much for the information.

I didn't realize that the units did that much calculating, and it wonder if my xantrex is as sophisticated.

Again, thanks for the information!
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Old 03-23-2014, 12:52 PM   #31
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That sounds like a good analysis based on your reading in depth the manual.

I never did that, so thanks much for the information.

I didn't realize that the units did that much calculating, and it wonder if my xantrex is as sophisticated.

Again, thanks for the information!
I wonder too...and based on my experience ...limited as it is....the algorithm needs lots'a work.
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Old 03-23-2014, 02:23 PM   #32
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I wonder too...and based on my experience ...limited as it is....the algorithm needs lots'a work.
While it's all very interesting, I don't really want my battery monitor to be as smart as possibly could be.

If the state of charge percentage is within a few percent or even 10%, I really don't care it just gives me a relative indication.

What is important, is the ammeter portion of the state of charge meter. That tells me if my charging system is working properly, it tells me what kinds of loads I'm applying to the battery bank.
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Old 03-23-2014, 02:31 PM   #33
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While it's all very interesting, I don't really want my battery monitor to be as smart as possibly could be.

If the state of charge percentage is within a few percent or even 10%, I really don't care it just gives me a relative indication.

What is important, is the ammeter portion of the state of charge meter. That tells me if my charging system is working properly, it tells me what kinds of loads I'm applying to the battery bank.
I can see that but what the heck do you know about electrical supply and all...

hey ...a friend just bought a 49 Meridian (former rag bagger)...and I have mentioned your existence and travels.

More than once and have told him there is very good info out there on the web to be had...hope you don't mind if I turn him on to all your posts resulting in you may have a new source of questions if you don't mind....
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Old 03-23-2014, 03:24 PM   #34
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While it's all very interesting, I don't really want my battery monitor to be as smart as possibly could be.

If the state of charge percentage is within a few percent or even 10%, I really don't care it just gives me a relative indication.

What is important, is the ammeter portion of the state of charge meter. That tells me if my charging system is working properly, it tells me what kinds of loads I'm applying to the battery bank.
I too, really just look at the current and what has come out of or into the batteries. the % I pretty much ignore, as well as TTG.

Now, i do record the voltage (see comments above) and the CE which is what I truly watch. Once it a while I have suspected that the CE is off, but it usually corrects itself before it becomes an issue.
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Old 03-23-2014, 05:16 PM   #35
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I guess the short way of putting it is that a good monitor simply logs all the factors an adept "manual" user would and makes the right calculations. Like anYthing else, if you don' allow it to work correctly (such as bringing the batteries to full charge every now and then), it's the old saw of "garbage in, garbage out".

We lived full time, for months at a time, on moorings, with journeys in between the length of the east coast that mostly involved anchoring or mooring. The Hatteras, as we inherited from POs, was a relatively AC intensive, energy inefficient and hungry boat. So managing the inverter batteries was a critical function for us. Like most things, if something is really important to you, you pay more attention to detail and learn a little more about it. Apparent from the responses here, that is not the case with most posters, so the casual or marina-centric boater can certainly dial things back a bit, focus-wise.
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Old 03-23-2014, 06:41 PM   #36
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Tim: it is best to re-set your Victron monitor at the dock and after being on shorepower charging for 3-4 days. That way you know your House bank is fully charged and in Float mode. Also...don't program it for 420Ah capacity when your batts are 4 years old. I'm not sure of the annual depletion rate for AGMs (you will find it on the net somewhere) but if just 5%pa at end 4 years IF you have done everything else right (not drawing below 50%, etc etc) you have only 342Ah there. It is best to program in a conservative view of your bank's total capacity to keep you well away from the minimum discharge levels. I have flooded golf cart batts, not AGM's, and I make it a practice to never go below 60% before recharging and I decrease the capacity programmed into my SOC meter (a MasterVolt...v similar) by 5%pa. I get 10-11 years out of my House bank, which I put down to this practice AND use of smart regulators.
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Old 03-24-2014, 07:57 AM   #37
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I've got some more research to do but the problem may be the unit hasn't figured out the batteries are not new and will not hold the 420 ah I told it. But it should know if voltage is below 11 volts for some time the bank is probably less than 80% SOC!

I'll call Victron and find out.
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Old 03-24-2014, 08:20 AM   #38
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Maybe I missed it, - Do you have separate starting and house banks?
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Old 03-24-2014, 08:25 AM   #39
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Tim

Maybe I missed it, - Do you have separate starting and house banks?
Yes, 4 house batteries, each 105 ah connected to the battery selector switch, switch position 2.
One engine start battery on a separate bank, 105 ah also connected to the battery switch, switch position 1.
One genny start battery isolated and not connect to the battery selector switch, 95 ah.
All AGM.
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Old 03-24-2014, 09:44 AM   #40
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Tim: it is best to re-set your Victron monitor at the dock and after being on shorepower charging for 3-4 days. That way you know your House bank is fully charged and in Float mode. Also...don't program it for 420Ah capacity when your batts are 4 years old. I'm not sure of the annual depletion rate for AGMs (you will find it on the net somewhere) but if just 5%pa at end 4 years IF you have done everything else right (not drawing below 50%, etc etc) you have only 342Ah there. It is best to program in a conservative view of your bank's total capacity to keep you well away from the minimum discharge levels. I have flooded golf cart batts, not AGM's, and I make it a practice to never go below 60% before recharging and I decrease the capacity programmed into my SOC meter (a MasterVolt...v similar) by 5%pa. I get 10-11 years out of my House bank, which I put down to this practice AND use of smart regulators.
ditto

Aquabelle is right on.

This is exactly what you must do to initialize your victron. Batteries must be fully, fully charged.
I have 980 rated amp hours, but put only 800 into victron since they are 4 years old.

And now that I think of it, I think I too, this morning will reset my victron since I have been under shore power for a week.
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