Batteries discharging to 11.9v at night

[Swamprat]

Hello. I'm new to solar and have set up my own system. It's been running well for a year, but now it's discharging to 11.9v even when not in use. The panels are still hooked up and will charge to about 12.2 during the day but by night falls to 11.9.

My configuration is:
2 x 100w Rich Solar panels
40amp mppt Controller
4 x Mighty Max Battery 6V 200AH SLA Battery (purchased new on Amazon)

Ghost Load?

Thanks for the help

Check your wires,,, a little corrosion can go a long WAY

 

[Don B. Cilly]

So if it's been holding a 100% or near 100% charge for a year;

No it hasn't. As said, 12.2V is barely 60%. Close to critical for lead-acid. And that's maximum charge. Definitely critical.
Now the reason it's gotten even worse is very probably what we've said. Your batteries didn't like it much, and by now they're not liking it at all.

As also stated, they have a decent chance of recovering - at least partially - but not if you continue to "abuse" them.
So find a way to charge them properly - ASAP.
Use a generator, run cables from your car... get some more panels :·) It's November, get even more panels :·)
Panels are reasonably cheap. Batteries are not.

Now, your charge settings look OK. Which probably means... your panels are quite inadequate.

 

[time2roll]

12.2 volts should be the bottom, not the top. You need these batteries at 14.4 to 14.8 every single day.
Could be a shorted cell and now you have a 10v battery. Take them down and get tested.

 

[740GLE]

The SCC has a shunt built in. I imagine you have the load connected to the SCC. So what has the daily production done, how does it compare to day one? How many whr/day are you using? Has that gone up? Any chance you could disconnect load for a couple days?

How are the panels wired series or parallel?

Does the SCC show you PV voltage input? Has that recently changed, voltage dropped? That’d show a possible connection issue.

 

[Tjbrancher]

No it hasn't. As said, 12.2V is barely 60%. Close to critical for lead-acid. And that's maximum charge. Definitely critical.
Now the reason it's gotten even worse is very probably what we've said. Your batteries didn't like it much, and by now they're not liking it at all.

As also stated, they have a decent chance of recovering - at least partially - but not if you continue to "abuse" them.
So find a way to charge them properly - ASAP.
Use a generator, run cables from your car... get some more panels :·) It's November, get even more panels :·)
Panels are reasonably cheap. Batteries are not.

Now, your charge settings look OK. Which probably means... your panels are quite inadequate.

The 12.2 is just the recent highest charge I'm getting. Over the past year its been much higher. This low voltage had just started happening over the past two weeks. I'll pull them out now and hook up to a charger. I thought 200w of panels would be enough. Bummer but yes I'd much rather get more panels than batteries. Thanks for your help.

 

[12VoltInstalls]

Over the past year its been much higher. This low voltage had just started happening over the past two weeks. I'll pull them out now and hook up to a charger. I thought 200w of panels would be enough. Bummer but yes I'd much rather get more panels than batteries.

Does that mean I need more panels or less

“Much higher” means what?

I just suffered several cloudy days and was uncomfortable that I was at 12V this morning. BUT by 11am or so I was charging at 14.2V and 16.x amps…
I have 400W into 600Ah(300Ah usable) and this time of year that is not enough. I need at least another 200W of panels and probably another 100Ah for my needs.

If you didn't see high charge volts regularly like basically nearly every day you killed your batteries imho.

Your batteries need 600- 800W

 

[Tjbrancher]

The SCC has a shunt built in. I imagine you have the load connected to the SCC. So what has the daily production done, how does it compare to day one? How many whr/day are you using? Has that gone up? Any chance you could disconnect load for a couple days?

How are the panels wired series or parallel?

Does the SCC show you PV voltage input? Has that recently changed, voltage dropped? That’d show a possible connection issue.

Wired in parallel. This pic is as far back as my record goes. Don't know what happened to the rest of the data. So it's only showing the low voltage but I think the production and consumption is correct.

 

[Tjbrancher]

The SCC has a shunt built in. I imagine you have the load connected to the SCC. So what has the daily production done, how does it compare to day one? How many whr/day are you using? Has that gone up? Any chance you could disconnect load for a couple days?

How are the panels wired series or parallel?

Does the SCC show you PV voltage input? Has that recently changed, voltage dropped? That’d show a possible connection issue.

 

[Tjbrancher]

“Much higher” means what?

I just suffered several cloudy days and was uncomfortable that I was at 12V this morning. BUT by 11am or so I was charging at 14.2V and 16.x amps…
I have 400W into 600Ah(300Ah usable) and this time of year that is not enough. I need at least another 200W of panels and probably another 100Ah for my needs.

If you didn't see high charge volts regularly like basically nearly every day you killed your batteries imho.

Your batteries need 600- 800W

I use to be at 14+ volts. I'm sorry I don't remember exactly. We did have a couple of cloudy days but the past few have been sunny. I have 4x 200ah batteries. That's 400ah useable right?

 

[Porch]

Not discounting that you have other issues, but you have two few panels, and too much battery, so the batteries have not been fully charged for some time. You need at least 500 watts of panels to keep that battery happy, not taking into factor what your load is.

My rule of thumb for led acid, if you should have 50% of your battery watt hours, in solar panel watt hours. In affect, you can charge your battery at 0% state of charge to 50% state of charge, in one sunny day. That puts you at needing 480 watts of solar (general guess, varies on location). That is also assuming you are using about 85% of your battery each night.

Used solar panels are cheap (and batteries are not), so I always way over panel by a lot.

And you may not have had the charge controller set to SLA, so it overcharged and and cooked the batteries when it could thinking they are flood acid battery and need a good boiling every now and then.

 

[Don B. Cilly]

I use to be at 14+ volts. I'm sorry I don't remember exactly. We did have a couple of cloudy days but the past few have been sunny.

So... it's November. Dreadful month :·)
Keep in mind that... 200W is "rated". Nominal. In improbable, ideal, not-real-life conditions.

I have 4x 200ah batteries. That's 400ah useable right?

It is, if you have two 6V in series for 12, and the other two paralleled to them, yes.
Still, November, nominal rated, it really looks like your panels just aren't charging your batteries properly.

200W nominal, in November, for 400 Ah of batteries... get them charged, sort out your charging issues, if they have been in a pitiful state of charge for not-too-long, chances are they might recover - at least partially.

 

[unsubscribed]

[As you can see from my handle, I've unsubscribed from this forum. (As a protest against overzealous Moderator moderation. (No option to delete my account.)) But I'm making an exception here to help others.]

The OP's problem is, at least in part, his Mighty Max brand batteries.

I ordered a pair of Mighty Max batteries from Amazon in 2020 for two different UPS's. Both batteries failed in a year. (Whereas I have typically seen 2 + years with other brands.) And these Mighty Max were supposed to be 9 A hr! (As opposed to 7.5 A hr for previous.)

So when the OP said that his batteries are failing after a year ...

I left a one-star review on Amazon to warn others about MM's poor longevity. But my review has mysteriously disappeared from Amazon.

So I post here in the hope of more permanence.

 

[Short_Shot]

It's been running fine for a year. I put the system together last September. Within the last two weeks things have changed to my current desperate condition.

It has clearly not been running fine, as your indicated voltages are far too low.

Most likely the batteries have been damaged. You might be able to improve things with a desulfation cycle.
As others stated I would suggest you add more solar panels to the mix to ensure they are fully charged each day. If you do not fully charge lead acid batteries each day you will develop issues over the long term which will slowly get worse and worse, as you suggest to be the case.

[As you can see from my handle, I've unsubscribed from this forum. (As a protest against overzealous Moderator moderation. (No option to delete my account.)) But I'm making an exception here to help others.]

The OP's problem is, at least in part, his Mighty Max brand batteries.

I ordered a pair of Mighty Max batteries from Amazon in 2020 for two different UPS's. Both batteries failed in a year. (Whereas I have typically seen 2 + years with other brands.) And these Mighty Max were supposed to be 9 A hr! (As opposed to 7.5 A hr for previous.)

So when the OP said that his batteries are failing after a year ...

I left a one-star review on Amazon to warn others about MM's poor longevity. But my review has mysteriously disappeared from Amazon.

So I post here in the hope of more permanence.

Lead acid batteries can last a long time with proper care and usage. If you are using them to their limits or beyond they can be ruined in 6 months. Its also pretty hard to screw up their design so badly that they have a significantly shorter life than other designs.

So first and foremost, I will point out that your anecdotal statements are not proof of anything without far more data on the matter.

A lead acid battery in a UPS should last several years unless its being cycled constantly, or is being overcharged very badly by that UPS. If your UPS is killing batteries in 2 years or less then the UPS or installation environment is most likely the source of the problem. Most UPS batteries last as much as 5 years if used sparingly and its not uncommon to see 10+ years.

If your UPS units are constantly at high temperatures (which means basically anything over 85F) it can ruin the batteries very quickly. This is common in server racks with bad ventilation and hot server rooms. Again, this is not the fault of the battery itself.

It sounds to me like you are going out of your way to criticize this specific brand by searching forums and complaining in other people's threads.
It also sounds to me like the issues you experienced are user error rather than the manufacturer's fault.


Regarding moderation, you are out of your mind if you think its "overzealous" here. This is the most laid back moderation team I have encountered in over 20 years of using forums, of which I spent my fair amount of time as a moderator myself on a board with several thousand active users (back in my paintball days). I suspect a common factor is present.

 

[740GLE]

Also “9ah” batteries vs what the OP is using isn’t quite apples to apples comparison other than the name on the side of the battery.

 

[Short_Shot]

Also “9ah” batteries vs what the OP is using isn’t quite apples to apples comparison other than the name on the side of the battery.

Imagine going on a crusade over a $24 battery.

 

[RCinFLA]

Lead-acid battery converts sulfur from sulfuric acid in electrolyte to lead sulfate on surface of plates. Recharging reverses process.

Initially the lead sulfate is a soft mossy coating. Left in this state for days it will create hard crystals that will not recharge easily. Allowed to harden to large crystals with additional time at discharged state and they will not recharge at all. The battery capacity is reduced by hardened lead sulfate crystals blocking plate surfaces.

It is important to fully recharge a lead acid battery as soon as possible to prevent lead sulfate crystals from forming.

You need to ensure you have enough recharge capability in a few good hours of PV production time, especially with possibility of weather limiting PV output for days.

Once a lead-acid battery becomes hard sulfated, the best you can do is a controlled overcharge, called equalization, that is so vigorous with bubbling and heating that it knocks loose the harden lead sulfate crystal causing them to drop to bottom of battery, This at least frees up plate surface but lead and sulfur is lost to active battery operation. Specific gravity (acid concentration) of electrolyte will be reduced due to sulfur no longer available to recharge electrolyte back to sulfuric acid. The equalization process is hard on battery and has to be carefully done to avoid too much other possible damage.

The equalization process consumes water in electrolyte and creates hydrogen and oxygen gases. For a sealed lead acid battery this is a problem as water cannot be added.

 

[Texas-Mark]

Could be a shorted cell and now you have a 10v battery.

This is my thought too. Kept them undercharged and then finally a cell shorted, and it is dragging the other battery down.

 

[Supervstech]

I use to be at 14+ volts. I'm sorry I don't remember exactly. We did have a couple of cloudy days but the past few have been sunny. I have 4x 200ah batteries. That's 400ah useable right?

No…
At 12V 4x200Ah would be 400Ah usable, but you are running 6V… so, 4x200 s 200Ah at 12V usable…

 

[Supervstech]

[As you can see from my handle, I've unsubscribed from this forum. (As a protest against overzealous Moderator moderation. (No option to delete my account.)) But I'm making an exception here to help others.]

The OP's problem is, at least in part, his Mighty Max brand batteries.

I ordered a pair of Mighty Max batteries from Amazon in 2020 for two different UPS's. Both batteries failed in a year. (Whereas I have typically seen 2 + years with other brands.) And these Mighty Max were supposed to be 9 A hr! (As opposed to 7.5 A hr for previous.)

So when the OP said that his batteries are failing after a year ...

I left a one-star review on Amazon to warn others about MM's poor longevity. But my review has mysteriously disappeared from Amazon.

So I post here in the hope of more permanence.

Moderators have changed around lately… what kind of moderation issues were you having? I try to limit my actions to reported posts and political stuff… besides spam that is.

 

[Short_Shot]

I think you are misunderstanding what your cc is telling you. When the cc says "100%", it is basing the percentage of charge on the top end that IT HAS MEASURED based on history. It is not giving you a TRUE measurement. You cc Believes that 12.2 is 'full' because that is the highest reading it has seen. The cc does not KNOW what a proper full charge is. When the cc tells you it is 100% charged, it is WRONG. You need a true battery monitor that has been programmed based on your specific battery specifications. Check your battery's documentation to find the REAL top-end voltage. You will find it is much, much higher than 12.2.

I've never known one of these to work that way.

Either it is an assumption based on voltage or has been programmed wrong for the capacity.

What specific device do you know to work that way by its documentation?