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.
I'm no expert, but these guys say 13.5 for float voltage.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...
At what current does your charger decide it is time to switch to float? Does it have a timer to shut off absorption?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.
Yea, I have that problem with a small charger I like to use on individual batteries in my golf cart. It never shuts off.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...
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.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.