bubbling/fizzling sound when charging my brand new AGM batteries

Thread Starter

BazsoDombiAndras

Joined Apr 26, 2015
65
That's just what I did. I had 2x 150 ah batteries which made the sounds, the seller has replaced them with new ones of the exact same type. The problem persists.
 

mikeileen

Joined Jun 10, 2015
3
All wet cell batteries does produce gases in the normal charge and discharge process if not the battery is dead, this is the normal chemical reaction of the liquid inside, there is a safety valve incase the battery overcharge and overgass , they all work the same only the design is different that's why in your case leave the battery disconnected the bubbling will stop after a while, please let me know if this happens Mike
 

Thread Starter

BazsoDombiAndras

Joined Apr 26, 2015
65
Hi Mike! Yes, if I stop the charging, the bubbling/fizzing/whispering stops after a while. What I'm not sure about is what these sounds are. The seller believes that it's the sound of the pressure relief valves opening shortly. If that's the case, then the battery is losing water (in form of oxygen and hydrogen), which is bad. Others think that it's simply the gasses moving inside the battery, gasses generated by the splitting of water into oxygen and hydrogen. If I'm hearing sounds, there must be quite some gasses in there. Do you think that they will all recombine?

For the sake of information:
These are 150Ah sealed (VRLA) gel batteries with AGM separator.

To quote the manufacturer:
Component ......Raw material
Positive ........Lead dioxide
Negative ........Lead
Container ........ABS
Cover ........ABS
Sealant ........Epoxy Resin
Safety valve .....EPDR
Terminal ........Copper
Separator ........AGM
Electrolyte ........Hybrid Gel

The manufacturer also says this:
Charge voltage @ 20 degrees C:
Cycle use: 14.4-14.8V (-30mV/degree C), max current 37.5A
Float use: 13.6-13.8V (-20 mV/degree C), max current: unlimited

I have a 3-step charger: bulk-absorption-float. The only problem with it is that the absorption phase end current (acceptance current) is fixed at 1A and I cannot change it. 1A is too much for these batteries. I've heard recommendations of 2% of nominal capacity for the absorption current end acceptance value. In my case that would be 3A. In other words when the batteries accept less then 3A, absorption should end. The charger's manufacturer refuses to make this a settable value because they fear that users will screw things up. The absorption is also terminated after a given period of time depending on how much the battery voltage was at the start of the charging cycle (absorption last for max 1 or 2 or 4 or 6 hours depending on initial battery voltage).

At first I tried to charge them according to this, setting the absorption voltage to 14.4V. There were severe bubbling sounds.
Then I tried to set the absorption voltage to 14.1V, there were still quite some sounds.
Finally I set the absorption voltage to 13.8V and the float to 13.5V. Sounds are not so loud and not so many, but they are there.

I also worry that if the absorption voltage is too low, the batteries will suffer form sulfation because they will never really be fully charged.
 

Thread Starter

BazsoDombiAndras

Joined Apr 26, 2015
65
I tried to replace the solar charger too, to see what happens. The charger I used was a 3-step (bulk-absorption-float) MPPT charger from Victron Energy. I replaced it with a Chinese PWM solar charge controller and set the target battery voltage to 13.8V. Same problem, same sounds. so it's not even the charger's fault.
Today I tried to take the batteries up to 14.1V, to see how much sound they make, but I gave up because at 13.9V they were bubbling and sizzling hard. They were cool to touch, though.
The brochure from the seller say the same thing as the manufacturer: that in cyclic use I can take them up to 14.4-14.8V. Well, perhpas that's not wise because I'm only discharging them to about 80% charge (20% taken off during the night). But 14.1V should be safe enough, right? All the articles I can find on the internet say that the gassing voltage at 20 degrees C should be above 14.3V.

I can't solve this mystery. I don't know why they are bubbling/sizzling starting at 13.4V (light bubbles/sizzles, far apart) and going wild at 13.9V already.

I'm just going to set the absorption voltage to 13.75V and the float to 13.55V and charge them like that. If they sulfate and die prematurely, the hell with it, I don't care anymore.
 

Thread Starter

BazsoDombiAndras

Joined Apr 26, 2015
65
Hello again!

I made another attempt to raise the absorption and float voltages to experiment a bit. I've set the absorption voltage to 14.05V (28.1V for the series of two batts).Something very interesting happens!

I can hear some light fizzing/boiling/gurgling from one of the batts in series. What's interesting is that if I measure the voltages individually for the two batts in series, the quiet one is at 14.01V and the fizzing one is at 13.92V. How can this be? When they are off charge, they both have identical voltage (around 12.95 fully charged), but when charge is forced into them, one opposes resistance and has lower voltage and also gurgles. What do you think?

Thanks!
 

Lestraveled

Joined May 19, 2014
1,946
All of my hands on experience has been with flooded lead acid batteries. From what I have read from google searches, an AGM battery should not make noise while being charged. The difference between 14.01 and 13.92 is insignificant. There is a fair amount of forum discussions about this. I would call other AGM battery manufacturers and ask them what they think.
 

GetDeviceInfo

Joined Jun 7, 2009
2,192
when connecting cells in series, you need to ensure that the charge depth of the cells are matched. Unmatched cells will be driven into extremes at the charge and discharge conditions. I'd suggest disconnecting your cells, run each through a charge/discharge cycle to gauge thier capacity, recharge them to full state and recombine. The group rating will inherite the weakest cells rating.

You may find that your problematic cell has a short which is causing localized evaporation. This will impact the A/hr rating. Ratings of cells that are not closely matched, should not be combined into a battery bank.
 
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Thread Starter

BazsoDombiAndras

Joined Apr 26, 2015
65
Thanks, GetDeviceInfo!

The strange thing is that when fully charged, the voltage of the two batts is exactly equal. The inequality only appears during charging. So even if after charged they appear to be equal, during the charge process the voltage difference shows up. Another strange thing is that 6 months ago I also measured the individual voltages during charging and there was a difference of only 0.01V, but after 6 months it's now 0.09V.

Anyway, I can't really charge them individually because I only have a 24V solar charger...
 
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GetDeviceInfo

Joined Jun 7, 2009
2,192
so a shorted cell may well then be overcharged. Do a cycle to compare, or retire the cell for backup, or let er rip and get what you can. If it's new, attempt a return under warranty. Voltage variance of .1 is of little concern.
 
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Thread Starter

BazsoDombiAndras

Joined Apr 26, 2015
65
Well, the thing is, when I originally bought the 2 batts, they both gurgled. So I returned them under warranty and got the current 2 ones. Now only one gurgles, but I doubt that they'd want to exchange them again after 6 months, especially both (and I would not be happy with one old and one new). I think I'll just hope for the best...
 

GetDeviceInfo

Joined Jun 7, 2009
2,192
2 years ago I paid $50 for a 1000 lot of 3200 mA/hr Lion batteries labelled for a major supplier, sourced from China, abandonded as freight. I cycle each one, grouped them and combined into various 'batteries' for local groups and thier various 'projects'. I still have a couple hundred left, but my findings have been that 1/3 performed as rated, 10% garbage, balance in between. Moral of the story is you don't know what you get until you test it.
 

ronv

Joined Nov 12, 2008
3,770
Well, the thing is, when I originally bought the 2 batts, they both gurgled. So I returned them under warranty and got the current 2 ones. Now only one gurgles, but I doubt that they'd want to exchange them again after 6 months, especially both (and I would not be happy with one old and one new). I think I'll just hope for the best...
I'm no expert, but these guys say 13.5 for float voltage.
http://batteryuniversity.com/learn/article/absorbent_glass_mat_agm
 

Thread Starter

BazsoDombiAndras

Joined Apr 26, 2015
65
ronv, not exactly. This is what batteryuniversity teaches:

"As with all gelled and sealed units, AGM batteries are sensitive to overcharging. These batteries can be charged to 2.40V/cell (and higher) without problem; however, the float charge should be reduced to between 2.25 and 2.30V/cell (summer temperatures may require lower voltages)."

That means absoprtion voltage of up to 14.4V per 12V battery and float voltage of 13.5-13.8V per 12V battery.
My battery alreday starts gyrgleing aroun 13.9-14V, so no chance to get to 14.4V without the sounds. The manufacturer says they can be charged between 14.4-14.8V and floated between 13.6-13.8V.
 

ronv

Joined Nov 12, 2008
3,770
ronv, not exactly. This is what batteryuniversity teaches:

"As with all gelled and sealed units, AGM batteries are sensitive to overcharging. These batteries can be charged to 2.40V/cell (and higher) without problem; however, the float charge should be reduced to between 2.25 and 2.30V/cell (summer temperatures may require lower voltages)."

That means absoprtion voltage of up to 14.4V per 12V battery and float voltage of 13.5-13.8V per 12V battery.
My battery alreday starts gyrgleing aroun 13.9-14V, so no chance to get to 14.4V without the sounds. The manufacturer says they can be charged between 14.4-14.8V and floated between 13.6-13.8V.
At what current does your charger decide it is time to switch to float? Does it have a timer to shut off absorption?
They are 150 AH right?
 

Thread Starter

BazsoDombiAndras

Joined Apr 26, 2015
65
Thank you, ronv!

My charger works in the following manner:
1. It starts charging in the "bulk" phase which means that it delivers as much current as it can and not care about the battery voltage until the battery voltage reaches the absorption voltage.
2. When the batteries reach the absorption voltage, the charger goes into constant voltage charging mode and keeps the batteries at the absorption voltage, which usually means that it limits the charging current based on what the batteries can naturally absorb at that voltage.
3. The charger switches from the absorption voltage to the lower float voltage when one of two conditions are met:
a) The charging current absorbed by the batteries at the absorption voltage drops below a predefined value.
b) A certain amount of absorption time has been completed.

Now the problem is with 3.a. That's because the current value absorbed by the batteries at the absorption voltage which ends the absorption phase cannot be customized. It is always 1A. That is way too low for my batteries. I wrote to the charger manufacturer about this, but they refuse to make it a customizable setting because they fear that users might screw things up. My batteries, baing rated at 150Ah, would need a stop current of 3-5A (for terminating the absorption phase).

However 3.b. compensates for the problems with 3.a. The charger looks at the battery voltage when the charging cycle starts and based on that it limits the absorption time. For example if the battery voltage is at 12V, it might limit the absorption phase to 4 hours, if the battery voltage is at 12.5V at the beginning of the charge cycle, it might limit the absorption to 2 hours and if the battery is above 12.75V, it might limit it to half hour. If the batteries are completely full, it limits the absorption to just a few minutes. This is not perfect, of course, so I'd really like to set the current value for 3.a.

All the above being said, the problem is still NOT with the charger. That's because I can hear the batteries fizzing/bubbling even at voltages as low as 13.9V, which is way below the gassing voltage of AGM or gel cells.According to every article about AGM and gel batteries out there, there is no way that overcharging could occur below 14.1V. Not to mention that the manufacturer recommends an absorption voltage between 14.4V-14.8V! and I know for a fact that the batteries are not full when they start making those sounds, because I've taken out perhaps 1kWh the previous night and next morning they make those sounds after taking in just 0.3-0.4 kWh or so.

Something is fishy...
 

ronv

Joined Nov 12, 2008
3,770
Thank you, ronv!

My charger works in the following manner:
1. It starts charging in the "bulk" phase which means that it delivers as much current as it can and not care about the battery voltage until the battery voltage reaches the absorption voltage.
2. When the batteries reach the absorption voltage, the charger goes into constant voltage charging mode and keeps the batteries at the absorption voltage, which usually means that it limits the charging current based on what the batteries can naturally absorb at that voltage.
3. The charger switches from the absorption voltage to the lower float voltage when one of two conditions are met:
a) The charging current absorbed by the batteries at the absorption voltage drops below a predefined value.
b) A certain amount of absorption time has been completed.

Now the problem is with 3.a. That's because the current value absorbed by the batteries at the absorption voltage which ends the absorption phase cannot be customized. It is always 1A. That is way too low for my batteries. I wrote to the charger manufacturer about this, but they refuse to make it a customizable setting because they fear that users might screw things up. My batteries, baing rated at 150Ah, would need a stop current of 3-5A (for terminating the absorption phase).

However 3.b. compensates for the problems with 3.a. The charger looks at the battery voltage when the charging cycle starts and based on that it limits the absorption time. For example if the battery voltage is at 12V, it might limit the absorption phase to 4 hours, if the battery voltage is at 12.5V at the beginning of the charge cycle, it might limit the absorption to 2 hours and if the battery is above 12.75V, it might limit it to half hour. If the batteries are completely full, it limits the absorption to just a few minutes. This is not perfect, of course, so I'd really like to set the current value for 3.a.

All the above being said, the problem is still NOT with the charger. That's because I can hear the batteries fizzing/bubbling even at voltages as low as 13.9V, which is way below the gassing voltage of AGM or gel cells.According to every article about AGM and gel batteries out there, there is no way that overcharging could occur below 14.1V. Not to mention that the manufacturer recommends an absorption voltage between 14.4V-14.8V! and I know for a fact that the batteries are not full when they start making those sounds, because I've taken out perhaps 1kWh the previous night and next morning they make those sounds after taking in just 0.3-0.4 kWh or so.

Something is fishy...
Yea, I have that problem with a small charger I like to use on individual batteries in my golf cart. It never shuts off. :D
Well, I'm not sure what is going on if your sure they are not close to being full. But, I don't think they will bubble without being overcharged. Obviously the float voltage of 13.5 is safe, but anything above that is suspect. I'm trying to think how we could fool your charger to make it like the fancy one in the link I sent.
 

Thread Starter

BazsoDombiAndras

Joined Apr 26, 2015
65
Well, actually I think it kind of works like that fancy one, except that it has no low-float mode (13.2V), just the regular float mode (13.5-13.8V - adjustable). And also the shut-off current is only 1A, not 0.05C.

I was thinking that the bubbleing could come from the fact that current is going into the batteries too fast (too much current), but it already bubbles with currents as low as 6-7A and the manufacturer says that they can be charged with 37.5A (0.25C)

Don't think of this bubbleing as something intense. It just a bubble here and there, not like boiling water. You could also describe it as the sounds of very little springs going off or like steam going through tiny holes. But just one in a few seconds, not all the time. Of course, if I raise the voltage, the sounds intensify and become closer to each other.
 
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ronv

Joined Nov 12, 2008
3,770
Well, actually I think it kind of works like that fancy one, except that it has no low-float mode (13.2V), just the regular float mode (13.5-13.8V - adjustable). And also the shut-off current is only 1A, not 0.05C.

I was thinking that the bubbleing could come from the fact that current is going into the batteries too fast (too much current), but it already bubbles with currents as low as 6-7A and the manufacturer says that they can be charged with 37.5A (0.25C)

Don't think of this bubbleing as something intense. It just a bubble here and there, not like boiling water. You could also describe it as the sounds of very little springs going off or like steam going through tiny holes. But just one in a few seconds, not all the time. Of course, if I raise the voltage, the sounds intensify and become closer to each other.
The link I posted has 2 absorption voltages, the standard one and one at 13.65 volts. Since yours don't bubble until 13.9 it seems it would "fix" it.
It is the voltage that makes it bubble. As long as the chemical reaction is going on your okay. But when it approaches full charge instead the chemistry releases hydrogen. That's the bubbles.
Does your charger ever switch to float or does it always time out?
 
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