Hydrogen sulfide from brand new batteries?

[Tariq0101]

So I bought two 200Ah 12v batteries to connect in series, they are manufactured in sept. 2021 so they lost some charge.
I charged each one on a 12v charger until they both rested on 13.8v and then installed them and set the mppt controller to FLD (I suppose it means flooded).
The next day the charge controller was charging on 29v and in the evening I started to smell a strong rotten eggs smell and after a couple of searches I found out it's hydrogen sulfide.
The batteries weren't hot or bubbling and there's no apparent acid water on the surface of the batteries.
I opened the windows and changed the settings to GEL (to give a lower voltage).

Today there isn't any sun (it's snowy and the charge controller giving 0.5 amps lol)
There's no rotten eggs smell, I measured the voltage of the bank and it's 28.2v (charge controller is saying 27.5v)
And I measured each battery, positive pole battery was 13.45v and the negative one was 13.8v.
The multimeter is old and could be unreliable I don't know for sure.
The batteries are connected with 10mm thick 30cm long copper cable.

The temperature was -5/15 yesterday and today it's lower, if that's relevant.
Considering all of the information above, Is it normal for new batteries to give off that smell?

 

[Tariq0101]

I wasn't paying too much attention to the charge controller, could it be that it's equalizing because it's the first day? I've set it to equalize once a month.

 

[Zil]

yes

 

[Tariq0101]

yes

But I've never read that anywhere, and the data sheet didn't say that.

 

[MichaelK]

In my personal experience, brand-new just-installed batteries always produce some sulfur smell as they first get settled in. After the first day though, that largely completely disappears.

I think changing the charging parameters to reduce the charging voltage is a mistake, and you should adhere to the guidelines that your manufacturer recommends. For my 24V system, I have the charge level set to 29.6, and my batteries are performing very well.

I think the high voltage readings you see are a combination of several things. Yes, your multimeter might be old and no longer accurate. A second phenomenon commonly seen with lead-acid batteries is that immediately after charging, you has a false "surface charge" that quickly disapates. You commonly let the battery "rest" for a couple of hours with no loads to get the most accurate voltage readings. I would expect a fully charged battery to be in the 25.4V to 25.6V range.

So, get a new multimeter off Ebay, which right now are running 10-12$. Fully charge the bank at the manufacturer recommended voltage, then disconnect the system at sunset and check the voltage after ~6pm.

 

[Tariq0101]

In my personal experience, brand-new just-installed batteries always produce some sulfur smell as they first get settled in. After the first day though, that largely completely disappears.

I think changing the charging parameters to reduce the charging voltage is a mistake, and you should adhere to the guidelines that your manufacturer recommends. For my 24V system, I have the charge level set to 29.6, and my batteries are performing very well.

I think the high voltage readings you see are a combination of several things. Yes, your multimeter might be old and no longer accurate. A second phenomenon commonly seen with lead-acid batteries is that immediately after charging, you has a false "surface charge" that quickly disapates. You commonly let the battery "rest" for a couple of hours with no loads to get the most accurate voltage readings. I would expect a fully charged battery to be in the 25.4V to 25.6V range.

So, get a new multimeter off Ebay, which right now are running 10-12$. Fully charge the bank at the manufacturer recommended voltage, then disconnect the system at sunset and check the voltage after ~6pm.

You're right the smell went away completely the next day.
The other problem that I'm seeing is that batteries don't have same voltage, the voltages are in the image below.
I fully charged them individually before installation.
Will the equalization process solve this?
This is the first time I use 24 volts excuse my little knowledge ?.

 

[MichaelK]

Are those electrolite level indicators on your batteries? I've never seen those before! Fancy!

I would get the two battery's voltages as close as you can first, then equalize. Then I would say you are good to go.

 

[Tariq0101]

Are those electrolite level indicators on your batteries? I've never seen those before! Fancy!

I would get the two battery's voltages as close as you can first, then equalize. Then I would say you are good to go.

Yeah those are water level monitors, they save you a lot of time and very cheap, I highly recommend them.
To get them as close as I can, can I just connect them on parallel overnight

 

[chrisski]

I don’t know if this effects voltage readings but:

1)The battery cables seem kind of small. Like 10 gauge or 8 gauge. That’s fine if you’re limited to 30 amps or 50 amps. I could be wrong and they may be thicker than they look.

2) The top connector seems like it should have a battery lug, but you’ve rigged a round post connector to fit on a rectangular post. Again, may be fine, but makes me think impedance issues,

I don’t know if you can connect them parallel overnight with a possible inrush of current, but I would put them on my battery charger one at a time to get them evenly charged and then hook them up again.

I’d also check with a hydrometer to make sure cells are even.

 

[Tariq0101]

I don’t know if this effects voltage readings but:

1)The battery cables seem kind of small. Like 10 gauge or 8 gauge. That’s fine if you’re limited to 30 amps or 50 amps. I could be wrong and they may be thicker than they look.

2) The top connector seems like it should have a battery lug, but you’ve rigged a round post connector to fit on a rectangular post. Again, may be fine, but makes me think impedance issues,

I don’t know if you can connect them parallel overnight with a possible inrush of current, but I would put them on my battery charger one at a time to get them evenly charged and then hook them up again.

I’d also check with a hydrometer to make sure cells are even.

The wire is 10mm thick, I think it's gauge 8, the average current going through is 10 amps, never more than 15.
I used the round connectors because I couldn't find copper lugs locally and those connectors are (almost) pure copper, shipping the lugs from another place would cost way more than their price.
I don't think it's a connection problem since everything is copper between them and tightened.
I'll try to charge them equally again and see if the voltage will vary again.
Thank you all for your help

 

[Horsefly]

The wire is 10mm thick, I think it's gauge 8, the average current going through is 10 amps, never more than 15.
I used the round connectors because I couldn't find copper lugs locally and those connectors are (almost) pure copper, shipping the lugs from another place would cost way more than their price.
I don't think it's a connection problem since everything is copper between them and tightened.
I'll try to charge them equally again and see if the voltage will vary again.
Thank you all for your help

If the wire (not the wire+insulation) is 10mm thick, it's 3/0 wire, which is pretty big. I don't think you have 3/0 wire.

 

[Tariq0101]

If the wire (not the wire+insulation) is 10mm thick, it's 3/0 wire, which is pretty big. I don't think you have 3/0 wire.

It is 10mm without insulation, it's the same one I'm using from the panels which are 60 feet away from the charge controller.
the batteries are huge (75kg each) and maybe that's why the wire looks small.

 

[Tariq0101]

@Horsefly @chrisski @MichaelK
Sorry for tagging you all, I just have one small last question.
If I connect my 12v charger to one of the batteries without removing any of the current connections, is there going to be a short circuit?
I'm 99% sure that it won't be, but I'm not taking the risk ?.
Of course I'll shut down the inverter and the controller.

 

[Horsefly]

It is 10mm without insulation, it's the same one I'm using from the panels which are 60 feet away from the charge controller.
the batteries are huge (75kg each) and maybe that's why the wire looks small.

Sorry, but you can't convince me that is 3/0 wire, especially if you have it running 60 feet from the panels to the charge controller. Not a chance. There isn't a charge controller made that can take 3/0 wire. The cheapest you would find 3/0 wire is probably over $5/ft, and that is really not very good wire. 60 ft each way is 120 ft, x 5$ is $600. Did you spend $600 for the wire to the charge controller? Nah, I didn't think so.

@Horsefly @chrisski @MichaelK
Sorry for tagging you all, I just have one small last question.
If I connect my 12v charger to one of the batteries without removing any of the current connections, is there going to be a short circuit?
I'm 99% sure that it won't be, but I'm not taking the risk ?.
Of course I'll shut down the inverter and the controller.

No, it won't cause a short. It doesn't even matter if you shut other stuff down, although it probably isn't good to power your inverter from the charger.

 

[chrisski]

I really think the wiring is 10 mm2 Which is 8 AWG in American,

 

[MichaelK]

If I connect my 12v charger to one of the batteries without removing any of the current connections, is there going to be a short circuit?
I'm 99% sure that it won't be, but I'm not taking the risk ?.
Of course I'll shut down the inverter and the controller.
[/QUOTE]
Honestly, I've never tried myself, so I can't say for sure? But, it just takes a minute to wrench off the bolt, so why not?

BTW, I think Chrissky is correct, it's 10mm2 wire. It might be marginally OK for run of the mill loads, but once you put a serious load on the inverter it is likely to be problematic.

 

[MichaelK]

@Horsefly @chrisski @MichaelK
If I connect my 12v charger to one of the batteries without removing any of the current connections, is there going to be a short circuit?
I'm 99% sure that it won't be, but I'm not taking the risk ?.
Of course I'll shut down the inverter and the controller.

@Honestly, I've never tried myself, so I can't say for sure? But, it just takes a minute to wrench off the bolt, so why not?

BTW, I think Chrissky is correct, it's 10mm2 wire. It might be marginally OK for run of the mill loads, but once you put a serious load on the inverter it is likely to be problematic.

 

[chrisski]

For reference, I have a 300 watt 24 volt inverter charger on a crate build I have 8 AWG on. For that case it’s plenty. 8 AWG is Probably even good for a 12 volt 300 watt inverter.

If it’s an inverter like 1000 watts, not so good.

 

[Tariq0101]

For reference, I have a 300 watt 24 volt inverter charger on a crate build I have 8 AWG on. For that case it’s plenty. 8 AWG is Probably even good for a 12 volt 300 watt inverter.

If it’s an inverter like 1000 watts, not so good.

So should I put another 30cm piece alongside it or should I buy a thicker cable for that?
And if there was resistance in the cable, would that cause voltage variation or just heat up the cable?

 

[Tariq0101]

Sorry, but you can't convince me that is 3/0 wire, especially if you have it running 60 feet from the panels to the charge controller. Not a chance. There isn't a charge controller made that can take 3/0 wire. The cheapest you would find 3/0 wire is probably over $5/ft, and that is really not very good wire. 60 ft each way is 120 ft, x 5$ is $600. Did you spend $600 for the wire to the charge controller? Nah, I didn't think so.

No, it won't cause a short. It doesn't even matter if you shut other stuff down, although it probably isn't good to power your inverter from the charger.

Yeah you're right, it is gauge 8, I just told the guy to give me 10mm2 wire, I'm still new to all this.