AGM batteries - voltage falling


Jose Alegria
 

Dear Amelians

Based on your long PV experience I would like to pose the following problem and receive your best inputs:

I change my  8 MAstervolt AGM bateries less than 2 years ago.
Bateries: 8 Mastervolt  AGM 12/160

Last September I install 3 the solar panels  ( Panels:  3 X SunPower SPR-MAX3-400)  and 3 inverters  ( Invertores: 3 Victron Smartsolar MPPT 100/30) 
We begin use the boat this year from  30 days - 5 initial days at marina and last ones at anchor.
At marina I don´t have any problem- all time connected with shore power and mastervolt 60 Amp charger.
 At anchor - During the day everything goes well, but during the night the voltage comes from 28-27 V to 19 V as you can  bellow.
Screenshot 2022-05-24 at 12.29.25.png

Of course the fridge and freezer and 800 W inverter stop work around 21,5 V.
I have registrations from last 10-15 days and everyday occurs the same.
In the morning, the the sun comes and the batteries voltage comes up , and up and near midday I  have  the Victrons show floating and 27,15 V
IMG_9410.PNG

Any idea ?
Thank you
( actually at Calvi-Corsica )

José Alegria
A55#003MERIT
josealegr@...
Mobile: + 351 91 866 30 37



Dean Gillies
 

Hi Jose,
Sorry... bad news.

Based on your description, I would suggest that your batteries are showing significantly reduced capacity.  In other words they need replaced.  

This problem usually happens after the batteries are discharged (a few times) to very low state of charge. When this happens, the batteries start to act like batteries of much smaller capacity than they were originally.  So you started with a bank of 640Ah, but now they act like less than 100Ah only.  This means they look like they charge quickly and also discharge quickly. Every time you take them to 19V you make the problem worse.  

Think about this: Your panels yesterday produced a total of 4200Wh or ~175Ah @ 24V.  That's for the whole day.. how could your 640Ah batteries be charged from zero to full by lunchtime if the total energy produced by your solar was only 175Ah for the whole day?  The answer is that your batteries are acting like less than 100Ah battery, and that's why you run out of power every night.

With lead batteries you need to make sure you don't discharge too much. I always recommend no lower than 70% SOC, but the higher SOC you keep, the longer they live.

--
Dean Gillies
SV Stella *****,  Amel 54-154


Bill Kinney
 

Jose,

The situation you describe is not good.  At 19 Volts your batteries are completely empty, 0% charged.  Bringing them up to full charge voltage by noon means that the batteries have lost 50%, and probably much more, of their capacity to hold power. It is unlikely that they can be brought back to life, but MasterVolt might have a restoration procedure you can try.

There are many things that can cause this, some are the fault of the batteries, some are caused by improper charging.

One of the most common things to go wrong in a battery bank is ONE of the batteries develops an internal short, this causes overcharging of all the other batteries in the system, damaging them.  Here is how to check for that:

First, and easy test: After charging the batteries for an hour or so, touch each one.  Is one hotter than the rest?  That’s likely to be the source of the problem.

A more precise test:  When they seem charged, disconnect the batteries completely from the system.  Let them sit for an hour.  Now measure the voltage between the positive and negative terminal of each battery.  A fully charged battery will be ~12.8V, one with an internal short will  be closer to 10.8 Volts.

If the problem can be traced to one faulty battery, you probably have a warranty claim with MasterVolt.

If the batteries all test out identical, then we have to look more deeply into the system, your use and charging patterns to understand a cause.

Bill Kinney
SM160, Harmonie
Le Marin, Martinique


Courtney Gorman
 

Awesome answer diagnosis and treatment plan Bill. Well done 
Cheers 
Courtney 


On May 24, 2022, at 1:42 PM, Bill Kinney <cruisingconsulting@...> wrote:

Jose,

The situation you describe is not good.  At 19 Volts your batteries are completely empty, 0% charged.  Bringing them up to full charge voltage by noon means that the batteries have lost 50%, and probably much more, of their capacity to hold power. It is unlikely that they can be brought back to life, but MasterVolt might have a restoration procedure you can try.

There are many things that can cause this, some are the fault of the batteries, some are caused by improper charging.

One of the most common things to go wrong in a battery bank is ONE of the batteries develops an internal short, this causes overcharging of all the other batteries in the system, damaging them.  Here is how to check for that:

First, and easy test: After charging the batteries for an hour or so, touch each one.  Is one hotter than the rest?  That’s likely to be the source of the problem.

A more precise test:  When they seem charged, disconnect the batteries completely from the system.  Let them sit for an hour.  Now measure the voltage between the positive and negative terminal of each battery.  A fully charged battery will be ~12.8V, one with an internal short will  be closer to 10.8 Volts.

If the problem can be traced to one faulty battery, you probably have a warranty claim with MasterVolt.

If the batteries all test out identical, then we have to look more deeply into the system, your use and charging patterns to understand a cause.

Bill Kinney
SM160, Harmonie
Le Marin, Martinique


Dean Gillies
 

Hi Bill,
Great suggestions.  
Would you expect the chargers to enter the float state if there was a shorted cell?  I would have thought that the tail current would not settle down enough to allow that to happen. What do you think?
Cheers


--
Dean Gillies
SV Stella *****,  Amel 54-154


Bill Kinney
 

Dean,  

The answer here is, like so often, “it depends.”  Some chargers don’t look specifically at tail current, but rather time at absorption.  Those wouldn’t know anything about the short.  

With one bad battery in a string of 8, the power draw of the shorted battery can be small enough to allow a current based transition to float, depending on the settings, and the internal resistance of the other batteries.  

The Victron solar controllers have a bunch of ways they can be set up to transition to float, but in a system without a central controller, I THINK they are all time based, although the time in absorption can vary depending on the controller’s idea of the state of charge.

I’d definitely want to eliminate a shorted cell as the source of the issue, because if it WAS caused by a bad cell, you might not need to change anything else.  In the absence of a shorted cell, new batteries installed in to the existing system are likely to suffer the same fate if nothing is changed.

Bill Kinney
SM160, Harmonie
Le Marin, Martinique 


Dean Gillies
 

Hi Bill,
Thanks for that.  I believe the ...MQ controller is acting as the master in Jose's setup (from the pictures he posted), but as you say it may not be using tail current as a trigger.
  
I don't hold out much hope for any of the batteries in the bank after 25 consecutive instances of dropping to 19V and unfortunately they are out of warranty after two years, so I doubt Mastervolt will come to the party, but it would be really good to know if its a shorted cell or just low capacity across the board.  As you say, finding out "why" is the important thing at this stage.

Jose, can you post the settings of the three MPPT controllers and let us know about your mains charger(s), and other components in your system?  Battery monitor?
Did you find any evidence of a shorted cell?

--
Dean Gillies
SV Stella *****,  Amel 54-154


Jose Alegria
 

Dean

As you request all Victron MPPT are the following settings:


As chargers I have 2 Mastervolt 60 and 100 Amps and the standard alternator,


Tha batteries has only 22 months !.., not 2 years.
Tomorrow I sill have the Mastervolt Ajaccio dealer on board and after I will trll you the diagnosis.

Thanks

Jose Alegria
Amel55 #03-MERIT
+351918663037
Josealegr@...



No dia 26/05/2022, às 16:16, Dean Gillies <stella@...> escreveu:



Hi Bill,
Thanks for that.  I believe the ...MQ controller is acting as the master in Jose's setup (from the pictures he posted), but as you say it may not be using tail current as a trigger.
  
I don't hold out much hope for any of the batteries in the bank after 25 consecutive instances of dropping to 19V and unfortunately they are out of warranty after two years, so I doubt Mastervolt will come to the party, but it would be really good to know if its a shorted cell or just low capacity across the board.  As you say, finding out "why" is the important thing at this stage.

Jose, can you post the settings of the three MPPT controllers and let us know about your mains charger(s), and other components in your system?  Battery monitor?
Did you find any evidence of a shorted cell?

--
Dean Gillies
SV Stella *****,  Amel 54-154


Dan Carlson
 

Overcharging may be part of the problem. Particularly if you  leave your chargers on all the time when in the marina on shore power. Because every morning your MPPTs will start a new charge cycle and keep charging your batteries until they reach the 28.8v absorb voltage. Depending on the size of your solar and the current load they may take most of the day reaching that voltage. This could be holding the batteries at a higher voltage for a longer time than is good for them. 

This is also a concern for LiFePo4 batteries, where the longer your hold the batteries above 27v the more you push them up to 100%SOC, where they don't like to remain. 

Best regards, Daniel Carlson on sv BeBe, SM # 387


On Thu, May 26, 2022, 3:53 PM Jose Alegria <Josealegr@...> wrote:
Dean

As you request all Victron MPPT are the following settings:


As chargers I have 2 Mastervolt 60 and 100 Amps and the standard alternator,


Tha batteries has only 22 months !.., not 2 years.
Tomorrow I sill have the Mastervolt Ajaccio dealer on board and after I will trll you the diagnosis.

Thanks

Jose Alegria
Amel55 #03-MERIT
+351918663037



No dia 26/05/2022, às 16:16, Dean Gillies <stella@...> escreveu:



Hi Bill,
Thanks for that.  I believe the ...MQ controller is acting as the master in Jose's setup (from the pictures he posted), but as you say it may not be using tail current as a trigger.
  
I don't hold out much hope for any of the batteries in the bank after 25 consecutive instances of dropping to 19V and unfortunately they are out of warranty after two years, so I doubt Mastervolt will come to the party, but it would be really good to know if its a shorted cell or just low capacity across the board.  As you say, finding out "why" is the important thing at this stage.

Jose, can you post the settings of the three MPPT controllers and let us know about your mains charger(s), and other components in your system?  Battery monitor?
Did you find any evidence of a shorted cell?

--
Dean Gillies
SV Stella *****,  Amel 54-154


Alan Leslie
 

Our Victron MPPTwon't go into bulk mode if the battery voltage is sitting at float level, which it is when plugged into shorepower with our Victron Skylla charger on all the time, so, I doubt that this would be  cause of overcharging.
More likely the cause of failure is one or more failed batteries in the string and therefore none of them have been properly charged....as has been indicated before.
Do you have a battery balancer(s) in your system?
I assume you have parallel sets of 12V batteries in series...are the midpoints of those pairs all tied together?
My guess is that the answers to these questions are no, and therefore the system can easily get out of balance over time with some batteries being undercharged and some overcharged.
Over time that will lead to the situation described - substantial loss of capacity.
We have AGM batteries with balancers etc now for 6 years + , never discharged to less than 80% and usually no less than 85% (we are frugal DCusers) and they are only just now starting to show reduced capacity.
There's no doubt your batteries will need to be replaced.
 We are only now considering the alternatives to replace ours...replace AGM with AGM or go Lithium - it's still under consideration....
Cheers
Alan
Elyse SM437


Dean Gillies
 

Jose,
The default behaviour of your charge algorithm (for the 6 months your batteries were being charged by Solar and shore chargers) is as follows:

1. The maximum absorption time would be 1 hour (since the batteries would be at float voltage overnight).
2. The tail current would be 2A. 

As Alan indicated, the bulk stage each day would be almost non-existent since the voltage would rise very quickly from float to 28.8V, and would hold this voltage until either the current dropped to less than 2A (I believe that's the total of all 3 networked MPPT's, does anyone know for sure?) or a period of 1 hour elapsed. This does not seem like enough time at higher voltage to badly damage a battery bank over winter.

This does not eliminate overcharging completely, but in theory it should not be caused by the solar operating properly according to your settings.

Let's see if the technician detects a failed cell before we postulate further causes of the failed bank. Fingers crossed you can get some warranty assistance from Mastervolt.

Alan's comments about balancing are excellent for future consideration if you stick with lead batteries.

Cheers
Dean

 


--
Dean Gillies
SV Stella *****,  Amel 54-154


Jose Alegria
 



New developments:

The Mastervolt dealers comes and the batteries are tested after 20 hours of shhore power on with 60 Amp charger  and the results are bellow:

batteries.jpg

5 batteries with > 80 % and 3 batteries with 73,76 and 77%

The technician  don’t find any problem with installation, and any batterie at shortcut; the charger parameters are correct, reviewed all equipments .


BUT LAST NIGHT I DO A NEW TEST:

Last night at 22,32 with 60 Amp charger ON the values was:
IMG_9583.jpeg

Then I  disconnect the 60 Amp charger and at 22:35 the values was:

IMG_9585.jpeg

The consumption are regular during the night : if my battery bank was actually ± 80% of 640 Amp I have ± 500 Amp — If the statues of charge goes down 9% ( from 100% to 91% )  I use ± 45 Amp during all night

Today 9 hours later after some sun light the values was: 

IMG_9586.jpeg
But early in the morning the voltage fall down t o 21,20 V and the freezer and fridge stop work again.

IMG_9587.PNG


Ideas ?

Thank you for your support
Attachments area

José Alegria
A55#003MERIT
josealegr@...
Mobile: + 351 91 866 30 37




On Fri, 27 May 2022 at 15:48, Dean Gillies <stella@...> wrote:
Jose,
The default behaviour of your charge algorithm (for the 6 months your batteries were being charged by Solar and shore chargers) is as follows:

1. The maximum absorption time would be 1 hour (since the batteries would be at float voltage overnight).
2. The tail current would be 2A. 

As Alan indicated, the bulk stage each day would be almost non-existent since the voltage would rise very quickly from float to 28.8V, and would hold this voltage until either the current dropped to less than 2A (I believe that's the total of all 3 networked MPPT's, does anyone know for sure?) or a period of 1 hour elapsed. This does not seem like enough time at higher voltage to badly damage a battery bank over winter.

This does not eliminate overcharging completely, but in theory it should not be caused by the solar operating properly according to your settings.

Let's see if the technician detects a failed cell before we postulate further causes of the failed bank. Fingers crossed you can get some warranty assistance from Mastervolt.

Alan's comments about balancing are excellent for future consideration if you stick with lead batteries.

Cheers
Dean

 


--
Dean Gillies
SV Stella *****,  Amel 54-154


Bruno COTTE
 

I do think it is a battery problem . Looks like they don’t keep the charge . 

Envoyé de mon iPhone

Le 28 mai 2022 à 09:04, Jose Alegria <Josealegr@...> a écrit :




New developments:

The Mastervolt dealers comes and the batteries are tested after 20 hours of shhore power on with 60 Amp charger  and the results are bellow:

batteries.jpg

5 batteries with > 80 % and 3 batteries with 73,76 and 77%

The technician  don’t find any problem with installation, and any batterie at shortcut; the charger parameters are correct, reviewed all equipments .


BUT LAST NIGHT I DO A NEW TEST:

Last night at 22,32 with 60 Amp charger ON the values was:
IMG_9583.jpeg

Then I  disconnect the 60 Amp charger and at 22:35 the values was:

IMG_9585.jpeg

The consumption are regular during the night : if my battery bank was actually ± 80% of 640 Amp I have ± 500 Amp — If the statues of charge goes down 9% ( from 100% to 91% )  I use ± 45 Amp during all night

Today 9 hours later after some sun light the values was: 

IMG_9586.jpeg
But early in the morning the voltage fall down t o 21,20 V and the freezer and fridge stop work again.

IMG_9587.PNG


Ideas ?

Thank you for your support
Attachments area

José Alegria
A55#003MERIT
josealegr@...
Mobile: + 351 91 866 30 37




On Fri, 27 May 2022 at 15:48, Dean Gillies <stella@...> wrote:
Jose,
The default behaviour of your charge algorithm (for the 6 months your batteries were being charged by Solar and shore chargers) is as follows:

1. The maximum absorption time would be 1 hour (since the batteries would be at float voltage overnight).
2. The tail current would be 2A. 

As Alan indicated, the bulk stage each day would be almost non-existent since the voltage would rise very quickly from float to 28.8V, and would hold this voltage until either the current dropped to less than 2A (I believe that's the total of all 3 networked MPPT's, does anyone know for sure?) or a period of 1 hour elapsed. This does not seem like enough time at higher voltage to badly damage a battery bank over winter.

This does not eliminate overcharging completely, but in theory it should not be caused by the solar operating properly according to your settings.

Let's see if the technician detects a failed cell before we postulate further causes of the failed bank. Fingers crossed you can get some warranty assistance from Mastervolt.

Alan's comments about balancing are excellent for future consideration if you stick with lead batteries.

Cheers
Dean

 


--
Dean Gillies
SV Stella *****,  Amel 54-154


Slavko Despotovic
 

Hello Jose,

after 20 hours of charging with 60A charger you have 80% charged batteries? I would say that this is not ok. I have 11 years old Victron batteries that charge to 100% in less than that time . Have you recorded the charging current? What was the value after 20 hours? I bet that it was very low. Voltage of 22,3V @-3,1A is bad. This 11,15V per 12V battery. I would say this is 30% charged batterie.
What kind of test was done by Mastervolt technician? Did he disconnect all the batteries?
I would measure voltage on all batteries when you have 20V. If all of them are at 10V then you need a new batteries. To have a correct test of batteries one have to measure every battery separately. Open Circuit Voltage of 11,5V is close to 30% I would say.
I have 380Ah batterie bank and I am now connected to shore power in marina. I have 400W of solar I installed and 150W are removable. So together 550W. Few days ago I tested the system, disconnection the shore power. Fridge, freezer were on, I cooked on Induction. I performed test like being on anchor.  After 2,5 days I had 24,5V. When induction was running it dropped to 23V but then returned to previous value. I never went bellow 75% charge of the bank during the test.
I hope this helps.


--
Slavko
SM 2000
#279 Bonne Anse in Croatia


Jose Alegria
 

Slavo 
Quick answers:
He  separate all batteries - 
all show > 12,90 amp; 
charged 100%
Medium Batterie performance 80%

He only make tests with 100% charged
Maybe next Monday I will try make the same when voltage drop to 20-21V
Regards





Jose Alegria
Amel55 #03-MERIT
+351918663037
Josealegr@...



No dia 28/05/2022, às 10:11, Slavko Despotovic <slavko@...> escreveu:

Hello Jose,

after 20 hours of charging with 60A charger you have 80% charged batteries? I would say that this is not ok. I have 11 years old Victron batteries that charge to 100% in less than that time . Have you recorded the charging current? What was the value after 20 hours? I bet that it was very low. Voltage of 22,3V @-3,1A is bad. This 11,15V per 12V battery. I would say this is 30% charged batterie.
What kind of test was done by Mastervolt technician? Did he disconnect all the batteries?
I would measure voltage on all batteries when you have 20V. If all of them are at 10V then you need a new batteries. To have a correct test of batteries one have to measure every battery separately. Open Circuit Voltage of 11,5V is close to 30% I would say.
I have 380Ah batterie bank and I am now connected to shore power in marina. I have 400W of solar I installed and 150W are removable. So together 550W. Few days ago I tested the system, disconnection the shore power. Fridge, freezer were on, I cooked on Induction. I performed test like being on anchor.  After 2,5 days I had 24,5V. When induction was running it dropped to 23V but then returned to previous value. I never went bellow 75% charge of the bank during the test.
I hope this helps.


--
Slavko
SM 2000
#279 Bonne Anse in Croatia


Slavko Despotovic
 

Hi Jose,

12,9V after 20hours of charging does not warranty that battery capacity is 110Ah if the batteries are rated to be 110Ah. Your measurement after you disconnected charger are showing that battery capacity much lower than rated 110Ah. This is why you have 22V in the morning.
Maybe you should record charging current as you are charging now. Maybe one measurement every 15 minutes. The voltage and charging current. And when you disconnect charger measure the same. Keep your loads at minimum. Fridge, freezer..
Talk to Mastervolt technician,  he need to know that something went wrong with your batteries to prevent this happening again. 

--
Slavko
SM 2000
#279 Bonne Anse in Croatia


Bruno COTTE
 

How old are your batteries ? 

Envoyé de mon iPhone

Le 28 mai 2022 à 10:51, Slavko Despotovic <slavko@...> a écrit :

Hi Jose,

12,9V after 20hours of charging does not warranty that battery capacity is 110Ah if the batteries are rated to be 110Ah. Your measurement after you disconnected charger are showing that battery capacity much lower than rated 110Ah. This is why you have 22V in the morning.
Maybe you should record charging current as you are charging now. Maybe one measurement every 15 minutes. The voltage and charging current. And when you disconnect charger measure the same. Keep your loads at minimum. Fridge, freezer..
Talk to Mastervolt technician,  he need to know that something went wrong with your batteries to prevent this happening again. 

--
Slavko
SM 2000
#279 Bonne Anse in Croatia


Jose Alegria
 

Bruno

22 months !…


Jose Alegria
Amel55 #03-MERIT
+351918663037
Josealegr@...



No dia 28/05/2022, às 10:55, Bruno COTTE <cotte.bruno@...> escreveu:

How old are your batteries ? 

Envoyé de mon iPhone

Le 28 mai 2022 à 10:51, Slavko Despotovic <slavko@...> a écrit :

Hi Jose,

12,9V after 20hours of charging does not warranty that battery capacity is 110Ah if the batteries are rated to be 110Ah. Your measurement after you disconnected charger are showing that battery capacity much lower than rated 110Ah. This is why you have 22V in the morning.
Maybe you should record charging current as you are charging now. Maybe one measurement every 15 minutes. The voltage and charging current. And when you disconnect charger measure the same. Keep your loads at minimum. Fridge, freezer..
Talk to Mastervolt technician,  he need to know that something went wrong with your batteries to prevent this happening again. 

--
Slavko
SM 2000
#279 Bonne Anse in Croatia


Bruno COTTE
 

Sorry to say it can be a bad battery 

Envoyé de mon iPhone

Le 28 mai 2022 à 13:18, Jose Alegria <Josealegr@...> a écrit :

Bruno

22 months !…


Jose Alegria
Amel55 #03-MERIT
+351918663037
Josealegr@...



No dia 28/05/2022, às 10:55, Bruno COTTE <cotte.bruno@...> escreveu:

How old are your batteries ? 

Envoyé de mon iPhone

Le 28 mai 2022 à 10:51, Slavko Despotovic <slavko@...> a écrit :

Hi Jose,

12,9V after 20hours of charging does not warranty that battery capacity is 110Ah if the batteries are rated to be 110Ah. Your measurement after you disconnected charger are showing that battery capacity much lower than rated 110Ah. This is why you have 22V in the morning.
Maybe you should record charging current as you are charging now. Maybe one measurement every 15 minutes. The voltage and charging current. And when you disconnect charger measure the same. Keep your loads at minimum. Fridge, freezer..
Talk to Mastervolt technician,  he need to know that something went wrong with your batteries to prevent this happening again. 

--
Slavko
SM 2000
#279 Bonne Anse in Croatia


 

I am sure that you have one or more bad batteries. I could not read the battery test results on the pieces of paper.

Bill


CW Bill Rouse Amel Owners Yacht School
720 Winnie, Galveston Island, Texas 77550 
   


On Sat, May 28, 2022 at 7:30 AM Bruno COTTE <cotte.bruno@...> wrote:
Sorry to say it can be a bad battery 

Envoyé de mon iPhone

Le 28 mai 2022 à 13:18, Jose Alegria <Josealegr@...> a écrit :

Bruno

22 months !…


Jose Alegria
Amel55 #03-MERIT
+351918663037



No dia 28/05/2022, às 10:55, Bruno COTTE <cotte.bruno@...> escreveu:

How old are your batteries ? 

Envoyé de mon iPhone

Le 28 mai 2022 à 10:51, Slavko Despotovic <slavko@...> a écrit :

Hi Jose,

12,9V after 20hours of charging does not warranty that battery capacity is 110Ah if the batteries are rated to be 110Ah. Your measurement after you disconnected charger are showing that battery capacity much lower than rated 110Ah. This is why you have 22V in the morning.
Maybe you should record charging current as you are charging now. Maybe one measurement every 15 minutes. The voltage and charging current. And when you disconnect charger measure the same. Keep your loads at minimum. Fridge, freezer..
Talk to Mastervolt technician,  he need to know that something went wrong with your batteries to prevent this happening again. 

--
Slavko
SM 2000
#279 Bonne Anse in Croatia