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Bubbling sound with new AGM battery bank

off.the.grid

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Just set up a new battery bank in a 24V configuration 2S2P.
I've got the panels going through an epever controller and flicked on the first time last week to start charging the battery bank before I swap out the old batteries.

However after a couple of hours of charging, I noticed that I could hear bubbling from the battery bank.
I believe this was supposed to be bad for AGM batteries, although I read that they are designed to reabsorb the hydrogen back via a catalyst if they are not overcharging.
See https://homebatterybank.com/is-it-normal-for-my-battery-to-bubble-when-charging/
This is what the app was telling me at the time.
14.6v is the recommended boost charge voltage for these nomad E2 batteries. As you can see, it was only feeding 10A into the bank, which I wouldn't have thought would have been an issue.

Will the batteries be OK, or should I lower the charge voltages?

Float voltage is set to 27.6V

Screenshot_20220619-155747_EPEVER Pair.jpg
 
Even AGMs bubble. Yes, they absorb it, but you can still hear them bubble. It's normal. That article is a bit alarmist in its warning while seemingly contradicting itself with the correct information.

Charge your AGM per the battery spec. Include temperature compensation if possible.
 
Even AGMs bubble. Yes, they absorb it, but you can still hear them bubble. It's normal. That article is a bit alarmist in its warning while seemingly contradicting itself with the correct information.

Charge your AGM per the battery spec. Include temperature compensation if possible.
Ok thats reassuring, because reading many threads here suggest it should never happen!
 
Once charged the battery bank appears to have a normal voltage across the bank, but noticed when charging that some batteries measure different voltages across them. One measures 15V across and others are as low as 12.9V for example.
Is this normal?
 
How do you have the 2S2P wired?

I take it these were disconnected. I don't see how the volt could be different if still connected 2S2P.

These should be set up cattycorner, similar to this. If not, the amperage drop would change more extreme if both cables are on the same side.

1656641442053.png
 
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Once charged the battery bank appears to have a normal voltage across the bank, but noticed when charging that some batteries measure different voltages across them. One measures 15V across and others are as low as 12.9V for example.
Is this normal?

No. You will destroy your batteries.

Break the bank down and charge the 12V to full individually and then in parallel. Reconfigure for 24V once complete.
 
How do you have the 2S2P wired?

I take it these were disconnected. I don't see how the volt could be different if still connected 2S2P.

These should be set up cattycorner, similar to this. If not, the amperage drop would change more extreme if both cables are on the same side.

View attachment 100816
See this photo for the configuration.
Now I should also mention that the charger has only ever been putting in about 10A max into the whole bank. That's only like 2.5A per battery.
20220614_173526.jpg
 
No. You will destroy your batteries.

Break the bank down and charge the 12V to full individually and then in parallel. Reconfigure for 24V once complete.
Yes I've been reading a whole lot of stuff about batteries being out of balance, etc and needing to be charged individually.
I'm thinking that some of the batteries may be possibly overcharged.
Would it be a good idea to drain them a little first with a lightbulb and then recharge them?
Should a fully charged one measure 13V?
I just hope it hasn't done any damage.
I only had it charging for about 2 hours and I've left it disconnected until I know it's OK. The charge current was only about 10A across the whole battery bank, which is not a lot.

I spoke to the battery supplier and they told me you don't have to charge them individually from New because they come shipped fully charged from factory.
Anyway, they are trying to blame it on my charge controller bring faulty which i know is total BS.
 
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See this photo for the configuration.
Now I should also mention that the charger has only ever been putting in about 10A max into the whole bank. That's only like 2.5A per battery.

No. Series and parallel rules apply.

That's 5A per battery. The 2P halves the current and the 2S both experience the same current, so each battery is experiencing 5A average.

Yes I've been reading a whole lot of stuff about batteries being out of balance, etc and needing to be charged individually.
I'm thinking that some of the batteries may be possibly overcharged.

Definitely.

Would it be a good idea to drain them a little first with a lightbulb and then recharge them?

No. Please do as I indicated. Break the bank down and individually charge them as 12V and then in parallel. If nothing else, you need to at least fully charge them individually. That can be done without breaking down the bank.

Should a fully charged one measure 13V?

Only after a full charge and about 24 hours of rest (no charge/discharge).

I just hope it hasn't done any damage.

Depends.

I only had it charging for about 2 hours and I've left it disconnected until I know it's OK. The charge current was only about 10A across the whole battery bank, which is not a lot.

I spoke to the battery supplier and they told me you don't have to charge them individually from New because they come shipped fully charged from factory.

They are completely wrong, and they are either 1) completely ignorant of batteries or 2) lying to cover their ass.

Anyway, they are trying to blame it on my charge controller bring faulty which i know is total BS.

Ask them, "batteries in series always experience exactly the same current. How can two batteries that experience exactly the same current have different states of charge if they were at the same state of charge (full) from the start?"

The answer is, "They can't. They must have been at different states of charge when you received them."

I apologize. I should have picked up that you had 12V wired in series for 24V and the individual/parallel 12V charging should have been part of my initial response. All batteries/cells placed in series should be fully charged BEFORE placed in series.
 
Everything @sunshine_eggo says is correct. That is the same thing I’d do.
That's 5A per battery. The 2P halves the current and the 2S both experience the same current, so each battery is experiencing 5A average.
May seem like magic, but you can always test with an amp meter. I use a clamp meter that goes around a single conductor.
 
No. Please do as I indicated. Break the bank down and individually charge them as 12V and then in parallel. If nothing else, you need to at least fully charge them individually. That can be done without breaking down the bank.
I had a go at charging them individually and the charge voltage all went down to the same voltage for all of them, so i shut it off, but the resting voltage was still higher with a couple of batteries.
I was told by a supplier to drain them a little if they have been overcharged, and then to charge back individually.
 
I had a go at charging them individually and the charge voltage all went down to the same voltage for all of them, so i shut it off, but the resting voltage was still higher with a couple of batteries.
I was told by a supplier to drain them a little if they have been overcharged, and then to charge back individually.
Is there a pattern to them being higher? Like last off the charger?

I do hope these communications with the supplier are something written. I was at the Tesla sealer mentioning my roof is not ideal with solar, and the salesman said, "The good thing about solar is a little is really good." I got on their website and the instant quote said 12 kW of solar for in excess of $30k. To get more details, I'd need to put $250 down to lock in installation.

How will you drain these? I have a DL24 battery capacity tester and that can drain the amount you want.
 
I had a go at charging them individually and the charge voltage all went down to the same voltage for all of them, so i shut it off, but the resting voltage was still higher with a couple of batteries.
I was told by a supplier to drain them a little if they have been overcharged, and then to charge back individually.
I should add that I tried this last week, before investigating further with my multimeter to discover some batteries were charging at different voltages.
The charge voltage was starting to drop off to around the floating voltage range(according to the charge controller), so I went around each battery and did this and charge them individually as a single 12V battery, but when I connected the bank up again, they would still charge unevenly.
I hadnt measured the actual battery voltage after being charged until a few days afterwards, then I discovered that a couple were reading higher than the others, these are the ones that I suspect were overcharged.

Thats why I think at least a couple need discharging.
Is there a pattern to them being higher? Like last off the charger?

I do hope these communications with the supplier are something written. I was at the Tesla sealer mentioning my roof is not ideal with solar, and the salesman said, "The good thing about solar is a little is really good." I got on their website and the instant quote said 12 kW of solar for in excess of $30k. To get more details, I'd need to put $250 down to lock in installation.

How will you drain these? I have a DL24 battery capacity tester and that can drain the amount you want.
Yes, one battery in each of the series pairs reads higher than the other.

What voltage should I expect to read from a good fully charged battery?
I believe it should be about 13V?

I measured the batteries after they were charging together, one of them was reading around 13.8V and another one was about 12.9 in the same series string.
I think I need to drain the ones that read high and then charge back up.
He told me to use a lightbulb which I think would work well, he said you only need to do it for a few minutes and it should come back to the normal level.

I was just speaking with him on the phone, now this was the main distributor I spoke to, what complicates things is I got the batteries from another reseller of the same brand, I never dealt with this guy directly.

I wish I knew about all this before charging, I know I had all the charge voltages set correctly and everything.
Either way, I spoke to a couple of battery suppliers and they both told me I shouldnt need to charge each battery up first if they are new.
I wasnt aware that it would cause any issues charging them up if they were not charged equally, it never crossed my mind at the time, but it makes sense.
I just hope the batteries are OK, the batteries were not venting out steam or anything, just bubbling like a can of soda like others say here is normal.
It still seems a heavily debatable thing if its OK for them to bubble or not, but obviously 15V across a battery is not a good thing.
 
Ok voltages after resting on each battery is.
12.9v, 12.7v, 12.6v and 13v. Am going to discharge the 2 highest ones and charge up the other 2 reading low
 
Am now charging one battery that measures 12.6v.

See screenshots attached.
My main concern is the controller is putting in about .1V more than specified.
I'm wondering if lowering the "max" voltage addresses this, but not sure why its even a value to change when boost voltage is normal. Currently equalize voltage is set to 14.6v which is the specified range for boost charging anyway.
The voltage is dropping down as I speak, it's about 14.68v now, but was as high as 14.73 a minute or two ago.

I dont know how long I need to charge this for, but its not far off fully charged.
There is bubbling on this battery im charging, but its not very audible. I am standing by monitoring it anyway.
 

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Also noticed that max voltage doesn't appear to save to the unit. Perhaps it's not something you can set. Either way. Voltage has risen back to 14.8v.
Current has dropped off though. Bubbling is only just noticeable.


Edit. I've found that lowering the charge limit voltage addresses the voltage discrepancy, but why that's required is beyond me.
 

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CHARGING batteries is typically a multi-hour process. The charger should progress through bulk, absorption and float phases. A battery is not charged until it has been held at the absorption voltage until the current drops to 0.02C and then drops to float.

I suspect that you're not charging any of these batteries to full.
 
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