Anyone ever heard aggressive churning in a battery cell? GC2

[fastline]

Never in my life have I heard such a sound! Probably a 1yo pair of GC2 flooded. This noise has been going on for months! I am in there checking stuff and hear what sounds like a bear rolling over in only one cell of one battery. That is also the only cell to spit some acid out the vent. Borrowed time is a certainty, but anyone have thoughts what would even cause this?

This is a 2S/2P config and all battery voltages read the same, though it is all connected. My guess is a hydrogen bubble forming and heads up top. What is odd is the fluid level seems fine though I use extreme caution around that cell as I like my eyes.

 

[time2roll]

One year old? I would be thinking to separate the batteries and see where they rest. Probably indicate the bubbler needs replaced. If you like dip it with a hydrometer to get a reading. At one year old I would be looking at replacing the one battery.

 

[John Frum]

Call a priest.

 

[Vigo]

It does seem like an indication of an irreversible defect. Id replace it before the others get too old to be mixing new batteries in with.

 

[Checkthisout]

Never in my life have I heard such a sound! Probably a 1yo pair of GC2 flooded. This noise has been going on for months! I am in there checking stuff and hear what sounds like a bear rolling over in only one cell of one battery. That is also the only cell to spit some acid out the vent. Borrowed time is a certainty, but anyone have thoughts what would even cause this?

This is a 2S/2P config and all battery voltages read the same, though it is all connected. My guess is a hydrogen bubble forming and heads up top. What is odd is the fluid level seems fine though I use extreme caution around that cell as I like my eyes.

The cell is probably shorted.

Bummer.

What brand of battery?

 

[RCinFLA]

Flooded lead-acid batteries start to split water in electrolyte at about 13.5v for six series cells and gets more vigorous gas bulbing as battery rises higher in voltage during charging. At absorb voltage of 14.5v it will outgas quite vigorously.

This is likely what you are hearing and it is normal.

If you hear it continuously after battery is fully charged you are likely overcharging battery or have a single cell bad.

During charging, negative electrode gives off hydrogen gas and positive electrode gives off oxygen gas. This is why you need a vented area for lead acid battery so gas concentration does not get too great. It eats up water in electrolyte causing electrolyte level to drop and requires water replacement to bring electrolyte up to proper levels.

 

[Vigo]

It is almost certainly not normal in this context. Batteries are 2 years old and this noise has only occurred in one cell, and only for months, and has actually resulted in electrolyte leaving the vent cap and getting on top of the battery case.

My only idea comes from having accidentally momentarily shorted a lead 48v pack and actually shooting the vent cap off one set of cells (one cap shared by 3 cells on a marine battery). Basically instantly making a volume of gas that exceeded the ‘flow rate’ of the vent cap enough to seriously pressurize that cell until the cap literally shot off. Since ive seen that happen i suspect a similar cause for this, because you’re getting a single large gas bubble or ‘gas generating event’ instead of small distributed bubbles from normal charging. Its probably occurring because something is internally shorting one or more sets of plates in only that cell. That would mean it is a physical object or defect in an unservicable part of the battery. Thus: would be nice to ‘solve the mystery’ but you end up replacing the battery regardless.

Just my theory.

 

[fastline]

It really is a mystery because I disconnected that pair of batteries for a few days. Voltage was spot on and a quick load test showed normal. No doubt this is not normal behavior, but I have never seen it! Usually something like this is a shorted cell which causes the others to get over volted and boil badly. Those also would show poor voltage retention.

The noise nearly makes the battery move. I know what normal boiling sounds like. Sort of like a fish tank bubbler (obviously try to avoid that). This is like gas gets momentary trapped, then escapes to another part of the cell.

 

[RCinFLA]

You need to report what your charging absorb and float level voltage are and how long absorb is sustained.

Are you seeing a lot of water loss in electrolyte? A cell going bad often eats more water than others.

Golf cart batteries often die due to positive plate support grid oxidation from overcharging. Unloaded cell voltage and electrolyte specific gravity will be normal but when battery is loaded with some current the voltage drops quite a bit due to the high resistance of the positive plate grid corrosion.

 

[fastline]

My target charge parameters move with the temperature but usually I try to run to 14.2 bulk, and 13.8 float, but many days it just won't quite get there because the solar is well matched to the system so if there are clouds, it might tap 14V for a couple hours and never actually float.

I would say anything upper 13s will cause this condition but I have heard odd noises with no charging and voltage at mid 12s and working. just really odd that it has not completely died.

To my amazement, when I realized this condition, I checked fluid level and that cell was no different than the rest.

 

[Vigo]

Hopefully this doesn’t sound dumb but have you tried lightly striking the side of the battery case to see if you can correlate the sound/event to some physical motion?