Popping/Hissing sound coming from batteries, not charging/discharging

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Korishan

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Background:
I have a SU2200 UPS I've put into service, especially since we're getting into hurricane weather and it's at least nice to not have the router/computer/monitor flip out if a tree limb brushes up against the power line.
The batteries I've used are reclaimed fork lift batteries. These are 6V Lead Acids. They hold a charge, but can't quite deliver high amp loads, which is fine for only needing about 500W max.

Well, today, we had something happen to the power. I'm guessing a tree fell on the line down the road. Will check that out at a later time. However, I was inspecting the UPS and battery voltages and I heard a hissing, slight popping sound. So I took two of the covers off the flooded batteries. They were definitely making a sound.

Here's the thing, I know that while under charging conditions, Lead Acids can off gas. They can also do so under heavy loads. But the loads these would of experienced at the time of power failure would be very low (I wasn't hope for a cpl hrs and my monitors would of been sleeping at the time). And also, the UPS would off been off for awhile by the time I checked them.
When checking all the batteries, they were all 6.5V, or 52V for the string. I checked the temps on these two and they weren't noticeably any difference in temp from the others. I didn't have my laser thermal gun on me at the time so I didn't check for a few degrees difference.

I did notice tho, that these two batteries are swollen a bit. Could this have any thing to do with the noises? I tried to do a search and of course I get results of "batteries will hiss/bubble while charging" on every result.
 

floydR

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Hydrogen and oxygen gases aren't recombining causing pressure.? swelling of batteries. Especially if they are VRLA batteries agm,gel / valves plugged on flooded lead acids?
later floyd
 

Korishan

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No pressure build up. Not the Gel batteries. I have some of those, but those are fine. It's the flooded ones that were making noise

Also, the plates are covered in water, so they aren't running dry.

All batteries read 6.5V, so shorting seems a little not the issue here, I would think. Wouldn't if plates were shorting make the battery not read the full voltage of 6.5V?
 

OffGridInTheCity

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I hesitate to even comment as I know you (of all people) know what you're doing :)

>>All batteries read 6.5V, so shorting seems a little not the issue here,
I found this paragraph at web page https://homebatterybank.com/why-is-my-battery-hissing-and-what-should-i-do/

"... If the lead plates are all covered, then go ahead and wait a few more hours if you have the time and check the specific gravity of each of the cells. You can use a hydrometer like this one seen on Amazon and you’ll be able to tell if you have any cells that are bad within your battery which could also lead to overcharging since the other cells will be compensating for the weak one. "

Which implies that voltage could be OK but yet you could still have a bad plate? Is there any chance you can start isolating batteries and find 'the one' that's hissing? and narrow things down / maybe replace it so you could isolate it out to 'the bench' for more precise testing ....?
 

cak

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You pose a though one here. I would check the gravity to confirm the voltage readings. I suspect that one or more of the individual cells within the two failing batteries are off in some way since a 6v battery will have 3 cells in series. Did the batteries ever get exposed to freezing temperatures? Freezing, which when the batteries are low charge can happen pretty easy, is usually why mine have bulged. The only other thing I can think of is if they haven't been suppercharged in awhile or are just really old and so have lots of buildup on the plates that is causing issues. I am no expert here but from dealing with issues I have dealt with my lifelong off grid life what I would check.
 

Korishan

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Is there any chance you can start isolating batteries and find 'the one' that's hissing?
I know which 2 are the hissing ones. I can't split the battery up any smaller. These are the same that would be used in golf carts, too. Each single battery is rated as 6V.

cells that are bad within your battery which could also lead to overcharging since the other cells will be compensating for the weak one
I suppose this is a possibility. I can't actually test this as there is no safe/easy way to probe inside the battery to measure plate voltages. There are 5 little holes on the top side of the battery barely bigger than my my thumb.

Did the batteries ever get exposed to freezing temperatures?
I doubt it, I'm in Florida and these were used at a printing press.

he only other thing I can think of is if they haven't been suppercharged in awhile or are just really old and so have lots of buildup on the plates
This is a possibility too. I don't know how long they sat with low voltage. I also don't know how long they were actually used. The oldest battery is 4 years old.

I hesitate to even comment as I know you (of all people) know what you're doing
Well, there is a difference between lithium based batteries, and lead acid based batteries ;) And searching online for lithium is a lot easier to find what you're looking for, too.

However, knowing about lithium batteries, each cell is itself a self contained cell, kinda forget some of the simplest things. I "knew" there are a plates inside the lead acid battery. It didn't don on me that there are series connected "cells" inside that battery as well and one or more single cells could be over charged.
1625384509486.png


I suppose if 1 cell is shorting out, this could keep the overall temps down as the heat dissipates easily.
But what I don't get is, this is happening while the battery isn't being used. It was sitting about an hour possibly after discharging stopped. And I hadn't noticed the issue before (altho, where they are at is pretty noisy with fans).

These are used batteries that I don't know fully their capabilities. They also were not charged/discharged several times to attempt to revive them. I basically rushed them into service. I'm not to worried about them off gassing as the area they are stored in is very well ventilated, so no danger of hydrogen build up. These will all be replaced soon with the lithium packs I'm working on anyways. Just need to get the spot welder finished and get the packs built.
 

Korishan

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I'm not really sure if the hydrometer would give any definitive results here. But, I may try it out. They are really cheap at the local car parts store.

I recently got another car battery specifically for the purpose of spot welding, so I'll be making my lithium packs here shortly. So I may be pulling those lead acids out of service sooner than later. They were only tossed in under haste because my other UPS died and I needed something quickly since we're now in hurricane/stormy weather season.
 

cak

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There was the suggestion of checking things with a hydrometer... ( https://www.amazon.com/E-Z-Red-SP101-Battery-Hydrometer/dp/B000JFHMRU ) do these actually do anything useful / will you be trying that?
I gave not used hydrometers much but my understanding is that they give a much more accurate state of charge and state of health of the battery than a voltage reading. I also just had the thought that it would enable testing to see if one of the three cells in the battery is bad because each cell had its own acid solution to read so since you can't get individual cell voltage reasons but you could get individual cell gravity readings.
 

ynot

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I suspect that you have either or both a warped plate or an impurity lodged between two of the plates causing a small short, or local electrolysis just sufficient to cause outgassing, but not big enough to drain the battery quickly, it could even be a layer of sulphates or other contaminants causing a localized bridge between the bottom of two or more of the plates. Since the batteries were used, you have no way of knowing how they were managed & if they were topped up with Florida tap water you may even have interesting life forms within some cells <grin>.
 

hbpowerwall

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Can you put your multi meter down into the cells to measure the actual cell voltage (i know this is a thing on a 12v car battery) Sounds like a cell is failing
 

Korishan

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Can you put your multi meter down into the cells to measure the actual cell voltage (i know this is a thing on a 12v car battery) Sounds like a cell is failing
I thought of that, but I'd need probes that are close to 10cm long. And I don't fancy reaching two pieces of metal down through a hole that's only 2cm wide.
I think I'm just going to let these run as they are and replace them with a new batch of lead acids.

I recently came across a great deal, as far as lead acids go. Rural King (it's kinda like Bunnings, but a bit cheaper, minus the lumber, and more farm equipment. I couldn't figure out a comparable store down there :p ) has 6V 930CCA lead acid batteries marked down to $40. They are tractor grade, which means they are also HUGE.
18in/45cm wide


Ooooo, they lowered the price another $10!!! Now they are only $30! Holy crap, I gotta get them before they fly off the shelf :LOL: I do have to drive over to the next city (about 45miles/72km away) to get other 4.
 
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