swollen 6v interstate batteries

offgridcabin2015 · October 2021

So i'm trying to find a legit reason as to why or what is causing swollen batteries.

So if i'm taking care of my batts (which i am) and ihave a battery flex max 80 that is reg all of this .

why or what is causing sides of batts to be swollen?.

I can tell you that i'm NOT over charging for flexmax is doing it's job.

FLOAT;

Once the Controller has determined the battery is fully charged it reduces the voltage to a point where very little current is flowing to the battery. This will prevent the battery from over charging and heating up..

i have 8 six volt batts . to which only 2 of them swollen on the neg side. The water is super clean and still work awesome

As a precaution i removed the bank off and only have 4 6volt remaining (the benefit here is repeatability). note for this reason i'll never go to 48volts. Had i been 48v. i'd have no system what so ever.

I'm looking to learn from this and know what is causign this.

Thankyou.

Photowhit · October 2021

So I guess 3 strings of 2 batteries? Were both batteries in the same string?
Were you sure to connect the batteries so there was equal resistance with each string?
How old are the batteries?

First are the specific gravities of the swollen batteries hugely different from the others?

Sorry you feel 48 volts isn't for you... In a single string there wouldn't be the chance of over or under charging individual batteries in a string due to poor wiring.

offgridcabin2015 said:

The water is super clean and still work awesome

I guess you are talking about the electrolyte? Do you only use distilled water to top off your electrolyte?

offgridcabin2015 · October 2021

HI Photowhit, Thanks for your reply.

i have 2 strings of 4 batts each wires in series to iake 24v. These batts were on it's own string.
I use distilled water only, and it's clean as a whistle.

As far as the specific gravity. honestly i have not measured it. I do have a tool to do this.(fractometre)

My understanding is to do when batts are at rest for 3 hrs min . so I'll check when I'm home at night time.
Question. do i need to unhook ALL WIRES to accurate reading?

The batteries are 5 years old (note that i've lightly used for lights only at night) . i only discharge 20-30% usage/ meaning batts are 80/70 full and charge daily. The less i dod , the more years i have for cycles. , Batt terms are super clean. kept inside my cabin.

Hope this helps in knowing what is causing this. when i get the numbers i'll compare to my 1 bank that is operation able.

Thanks for the help.

Much appreciaated. Neil.

offgridcabin2015 · October 2021

note: had i been 48 volt , i'd be left without a system and if i even made a misake. 48v is lethal

mike95490 · October 2021

offgridcabin2015 said:

note: had i been 48 volt , i'd be left without a system and if i even made a misake. 48v is lethal

So you be aware and careful. There's plenty of 48v systems out there, and I don't see headlines and tombstones about them,

24v sytems are also dangerous, with overloaded conductors that would be just fine with a 48V system

Dave Angelini · October 2021

Not measuring SG would be just as bad on 48v as 24v. Probably worse with 24 v as you have to run strings. We get your point about having the extra string for times like this. I would just forget about what would happen with 48v as it is apples and oranges at this point.

Any flooded battery needs to be calibrated to enable it to go to float once the SG is correct per the bat manufacturer. Since you never did this (let alone EQ's) and are at 5 years, I would say for a cabin you did fine. Get ready for buying new batteries as winter is just about here!

Here is a link to an inexpensive/accurate but easy to use hydrometer. Made in the USA for less than $15. You are looking for all of the cells to be within .015 of each other. If they are .030 they can usually be corrected with EQ. Not always though and if they do not come up to spec, it is time to replace the bank. I am guessing your cells are off more than .030.

https://www.amazon.com/E-Z-Red-SP101-Battery-Hydrometer/dp/B000JFHMRU/ref=sr_1_6?dchild=1&keywords=easy+read+battery+hydrometer&qid=1634163865&sr=8-6

Good Luck!

offgridcabin2015 · October 2021

note . i already have a fractmetre see link

https://www.amazon.ca/Refractometer-Brewing-Making-Content-Mearsuring/dp/B006GG0TDK/ref=asc_df_B006GG0TDK/?tag=googleshopc0c-20&linkCode=df0&hvadid=335136531729&hvpos=&hvnetw=g&hvrand=1431030917805938898&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9061009&hvtargid=pla-569678492319&psc=1

Marc Kurth · October 2021

offgridcabin2015 said:

So i'm trying to find a legit reason as to why or what is causing swollen batteries.

So if i'm taking care of my batts (which i am) and ihave a battery flex max 80 that is reg all of this .

why or what is causing sides of batts to be swollen?.

I can tell you that i'm NOT over charging for flexmax is doing it's job.

By far most "swollen" batteries that I see in my business are caused by long-term undercharging, causing continual (and compounding) sulfation. Please understand that I am not accusing, I am simply sharing hands-on experience.

BB. · October 2021

I am no battery expert here... But as I understand:

Your refractometer showing max 1.130 SG (specific gravity)--If accurate for lead acid electrolyte--1.130 is around 30% or so state of charge--Severely undercharged

https://www.amazon.com/Antifreeze-Coolant-Refractometer-Automobile-Windshield/dp/B07DLDZFJX (example of "battery" refractometer)
http://www.trojanbattery.com/pdf/TrojanBattery_UsersGuide.pdf (page 22 for specific gravity chart)

The rough range of SG for lead acid batteries is from 1.120 (20% state of charge--try not to go below) to 1.172 SG or 50% SoC. And around 1.277 max SG for 100% SoC (lead acid battery SG varies with temperatures and initial fill SG--Lower SG is less stored energy but longer life... And higher SG fill is higher power and shorter life ("tropical" batteries may have lower SG fill).

More or less, don't let Lead Acid batteries sit below ~75% SoC (lower SG values increase the speed of sulfation--Day sulfation starts, in months battery has been rendered sulfated and pretty much useless).

For flooded cell lead acid batteries, they need to be recharged every 30 days (at 75F) to bring back from ~75% to 100% State of charge.

A couple of different hydrometers (from our hosts):

https://www.solar-electric.com/search/?q=hydrometer

Would like to review your charging settings, battery AH and voltage, array Wattage, rough location of system (nearest major city for hours of sun per day).

More or less, charging below 14.75 Volts (bulk--current limited by charge controller) to ~80-90% state of charge. Then hold absorb voltage of 14.75 for 2-6 hours of so--2 hours for shallow discharge, ~6+ hours for deep discharge at 50% or lower SoC).

Another method to determine if your battery is full is to monitor charging current. If you have the "correct" absorb voltage, more or less, the battery bank is full when the charging current falls below ~1% rate of charge (a 200 AH battery bank charging would be less than 2 amps @ 14.75 volts). If your batteries never drop below 2% rate of charge--Then your charging voltage may be too highlll, or the batteries are at end of life (2% or higher sustain rate of charge for many hours can overheat the batteries and even start a fire).

You can measure SG at anytime during charging--More or less, when the battery is "bubbling" (gassing), the bubbles help mix the electrolyte. You just have to be careful to knock bubbles off the float (if using that type of hydrometer).

More or less, you charge to full (absorb voltage held for 2-6 hours of so)... And Equalization charge (usually done for flooded cell lead acid batteries) you charge at a 5% to 2.5% rate of charge (200 AH * 0.05 = 10 amps) and check and log the SG every 30-60 minutes... When all SG readings stop rising, that is the "new" 100% SoC SG reading. As batteries sulfate, typically the maximum SG value falls (less sulfur in the electrolyte as it is "lost" to the sulfation of the lead plates).

If you are trying to estimate the state of charge of the lead acid battery bank by voltage--Then yes, you need to let the bank sit for 3+ hours for the chemistry to equalize (between plates and electrolyte). You don't need to disconnect the wires--Just try to have little load on the bank (if you measure "resting voltage" just after charging, you will have a high voltage reading that is less than accurate).

You should measure the voltage of each battery in your system (12.7 volt resting for FLA = 6.35 volts for a "resting" fully charged 6 volt FLA battery).

Usually, our first question is "how do you know your batteries are 100% full?"... Most of the time they are not full, but under charged to some degree or another.

Can be lots of reasons:

dirty/correded/lose battery to charger connections
too small of AWG cable from charge controller to battery bank (too much voltage drop)
calibration error with charge controller
misprogrammed charge controller (wrong voltage, bad remote temperature sensor, wrong absorb timeout, etc.)
your backup voltmeter/Digital Multimeter has almost dead batteries
your daily loads (AH / Watt*Hours) exceeds the amount of charging you can get from the sun
Not charging enough (allowing low SoC/SG), cause sulfation (fluffy grey lead sulfate turns into hard black crystals which no longer are part of charge/discharge chemistry).
Too much charging current/voltage--Excessive gassing (erodes plates, causes corrosion, high battery temperatures, possible exposing top of plates--Exposure to air ruins plates).
Lead Acid batteries (most batteries) "age" faster if stored/operated at higher temperatures... For every 10C/18F above 25C/77F, batteries will age 2x faster (1/2 life). For folks that have systems in cold climates (far north)--Their batteries can last much longer (cold soak during winter).
Batteries have not been wired in parallel "correctly"... The following link shows how to properly parallel:

http://www.smartgauge.co.uk/batt_con.html

There are also other physical signs of battery failures... Looking at the positive posts, they seem to be "extruding" out the top of the battery (a little bit). This is from corrosion of the positive plates and grid--Which does happen from normal charging (hydrogen+oxygen from charging/EQ--Oxygen does cause positive plate/grid corrosion over time--Cannot stop, it is part of normal aging).

There are lots of different tools you can use to estimate your system state of charge/performance... Battery Monitors. run from "cheap" (Amazon) to not cheap (monitors designed for solar power systems)... But they all have their issues (their SoC readings can "drift" from actual SoC depending on how the systems are operated).

If you got 3-5 years (aging) from "golf cart" FLA batteries at normal room temperatures--That is about average. So you may not have shorted their lives very much.

-Bill

Dave Angelini · October 2021

offgridcabin2015 said:

note . i already have a fractmetre see link

https://www.amazon.ca/Refractometer-Brewing-Making-Content-Mearsuring/dp/B006GG0TDK/ref=asc_df_B006GG0TDK/?tag=googleshopc0c-20&linkCode=df0&hvadid=335136531729&hvpos=&hvnetw=g&hvrand=1431030917805938898&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9061009&hvtargid=pla-569678492319&psc=1

So you have the tool but did not measure SG. Seems the same as not having the tool.

Photowhit · October 2021

offgridcabin2015 said:
The batteries are 5 years old (note that i've lightly used for lights only at night) . i only discharge 20-30% usage/ meaning batts are 80/70 full and charge daily. The less i dod , the more years i have for cycles. , Batt terms are super clean. kept inside my cabin.

While cycle life is one aspect of battery longevity, Flooded lead acid batteries start aging when born. In general 5-7 years for golf cart size batteries is about the limit. A few with special attributes might go 10, Trojan and I believe Crown make some that can go 10-12.... Outside of those, batteries kept in extreme cold can go longer.

Keeping the wiring the same distance and size is important for batteries to have equal charging and discharging. Here is a site that will try to explain the differences in resistance in wiring.

SmartGauge Electronics - Interconnecting multiple batteries to form one larger bank

In addition, we haven't spoken on Equalizing. Equalizing is a slight over charging of a fully charged battery bank, to allow slightly under charged cells to 'catch up'. Once a battery bank becomes out of balance it's hard to correct. That's the reason we check specific gravity (SG) to help us understand the battery health.

Equalizing is done on a fully charged battery and the voltage is actually increase above the Absorb level by around 7-10% to allow the flow of more current into the battery bank. This is Morningstars chart, stage 1 would normally be called 'bulk' by most of the solar people I know. The PWM would be called Absorb, I think the use PWM because the charge controller limits the voltage and their MPPT charge controller drop back into PWM mode. I'll post my battery charging cycles info after this post.

Rolls/Surette(?) and I describe 2 types of equalizing. A maintenance equalizing done monthly or other short period up to 6 months to keep batteries in balance, and a corrective equalizing, done when 1 or more cell is seriously out of balance.

Corrective equalizing is checked every hour to see if the SG has increased in the low SG cells. I stop after I don't see an increase in in 2 hours. Others have gone to continuing the equalizing even longer and even increasing the battery voltage during the equalizing.

Trojan Tips 5 - Equalization is Key to Extending Battery Life and Performance - YouTube

Photowhit · October 2021

Just for nomenclature's sake, since I posted a link to a UK sire Equalizing is often referred to as 'Boost' cycle in Europe/Asian countries.

The voltage you are seeing is the system voltage and not the battery voltage. If you are connected to charging or a load it will effect the system voltage.

During charging, there are basically 3 stages of charging, Bulk, Absorb, and Float.

BULK;

First thing when charging starts you will be in bulk, the voltage rises from what ever the system voltage was to a set point, around 14.5 volts. At that point the Charge controller stops the voltage from rising. Higher voltage can damage sealed batteries.

ABSORB;

Once the battery hits the preset point the charge controller keeps it at that point. Your batteries are roughly 80% full. Flooded batteries will start accepting less current at 80-85% full AGM/Sealed may go a little longer before accepting less current.

On many controllers you can set this point, Some will have different presets for Flooded, and sealed batteries, or flooded, AGM, and sealed batteries.

The charge controller has a couple ways to know when to switch to float, Most inexpensive Charge controller are just timed for 1.5-2 hours. Some will also see less current flowing through the charge controller and shut it down when minimal current is flowing through the controller. On more expensive charge controller. You can set battery capacity to give the Controller a better idea of when to stop. you can also set a longer Absorb time. Or set 'end amps' a amount of amps flowing through the charge controller to stop Absorb and switch to the final stage.

FLOAT;

Once the Controller has determined the battery is fully charged it reduces the voltage to a point where very little current is flowing to the battery. This will prevent the battery from over charging and heating up.

While in 'Float' the charge controller watch for voltage drop, which would indicate a load. If the voltage begins to drop the charge controller will allow as much current to flow from the panels/array to compensate and maintain the voltage. If the voltage can be maintained, the load will in essence be running directly off the array/solar. If the voltage drops below the preset float voltage, the controller may start a whole new cycle if it stays there for a period of time.

The system voltage drop you see at night when the sun goes down is the charge controller moving into a resting mode with no energy to contribute to the system.

The morning voltage may reflect a load present that is effecting the voltage level. With sealed batteries, you would want to disconnect the battery from the system and allow it to 'rest' for a while to get an accurate idea of it's SOC (State Of Charge) from the voltage, This is not required if checking Specific Gravity.

State of Charge (SOC) based on Specific gravity is generally runs around this;

Battery State-Of-Charge Chart 12 Volt Battery Voltage amp Specific Gravity

Battery State-Of-Charge Chart 12 Volt Battery Voltage amp Specific Gravity

Specific gravity per cell is in the far right column, I generally use 1.18-1.20 as 50% and it somewhat depends on what specific gravity the battery began with. For a while 15-20 years ago Trojan was using a 1.26 SG electrolyte, and I think lower SG around that range can be/are used in hot climates. Most use 1.28-1.3 SG electrolyte.

BTW - I don't know what type of inverter you are using, some inexpensive inverters will shut down during equalizing. My Prosine is will beep since it's right on the verge of too high a voltage during equalizing my 24 volt system at 31.5.

You should be able to get the correct equalizing voltage from the battery manufacturer. Some don't specify, Batteries from Sam's Club and maybe Costco. I'd shoot for 31 volts in a 24 volt system.

offgridcabin2015 · October 2021

hey peeps i wanted to give some clarity. the refractormeter is not the one i own was just an example of basically what it looked like.
My inverter is a great inverter. flexmax 80 (outback)

Image: https://us.v-cdn.net/6024911/uploads/editor/14/dr3wln6xt3pu.jpg

.

I have added the pic of the 2 swollen batts, so you all can see. and i'll upload pic of my power wall too.

Image: https://us.v-cdn.net/6024911/uploads/editor/53/got89iabcydu.jpg

offgridcabin2015 · October 2021

Question on wiring batts to the specs you shared for perfect balancing. (wiring option 4) so honest not sure how to wire that up for i'm 6v batts and have to wire + to neg to make 12v and so on to maake 24v.

Image: https://us.v-cdn.net/6024911/uploads/editor/c7/hc2nzm3xuhau.jpg

wellbuilt · October 2021

There is no perfect battery string , the best thing is a 48vsystem with 8 6v battery’s in series .

Your pic is for 6v Batteries that are series parallel to 24 volt , or 12v battery’s to 48 volt . I would just run 4 6v battery’s in series for 24 volt.

You could use large l 16s 380AH or larger and just run in series .

I would just run to strings of 4 6v battery’s
I’m using 2 strings of 8 battery’s for 48 volts and it works fine .

offgridcabin2015 · October 2021

confused my your cell soc being so low. i'll upload soc for 6v cell . here's my math 2.122 x 3 cells is 6.37v. But in the above chart it 'listed as 1.28. not making any sense to me . ( i'm assuming NOT for 6v ) correct/

offgridcabin2015 · October 2021

my system also is working fine. I never went 48v for i don't have a precharge resitor . and I would have to buy 48v inverter and 48 to 12v step down. Expensive.

I was looking to fine tune system and was given this info buy this very channel.

I have also check SG on the 2nd battery banks and they are PURFECT. all cells 1.26 / temp of cabin is 22 degree Cel.

Photowhit · October 2021

Marc Kurth said:

wellbuilt said:

There is no perfect battery string , the best thing is a 48vsystem with 8 6v battery’s in series .

Interesting. I much prefer a single string of 2v batteries for a 48v battery bank.

Which is pretty much what 8-6v batteries in series are, with less mechanical connections.

Of course I prefer a 48 volt forklift/traction battery. A single string of 24 2 volt cells with only 2 mechanical connections where it connects to the system. Indeed every time I see batteries batteries with stacked connections, I cringe!

wellbuilt · October 2021

Marc photoswhit I’m trying to stay in the Spirit of the forms diy .
OGC is using GC battery’s .
I would love to get some 2v cells or forklift battery’s my self but the Golf cart batteries are Inexpensive 16 for 1500$

wellbuilt · October 2021

You must be mixing up SG with volts 1.280 is 100% charged .
1.26 is not a perfect #

offgridcabin2015 · October 2021

@well built. 1.26 is 90% charged and i took them off the other bank at this SG. SO what im saying is 1.26 is great. the swollen batts are still useable and i feel i can still put them in servie and charge up to 1.28. The enitre post isabout swollen batts not all this side chadder.

BB. · October 2021

Just watch the battery temperatures... These batteries can develop "higher internal resistance" (more heat generated during charging and discharging) and can gas faster during charging.

Also, as lead acid batteries age, they have higher self discharge.... More or less, if you see 2% or higher charging current during float (continuous current draw)--The battery bank can overheat and fail...

If the batteries continue to work for your needs and don't over heat (and the "weak batteries" don't self discharge the bank)--Why not use time.

If you put the swollen batteries in the same series string(s)--You can use a Current Clamp meter (DMM) and monitor the charging/discharging current and battery behaviors. Also monitor each battery's voltage--If all is "OK", the all batteries should be very close in terminal voltages... If you start to see one or more batteries deviate (higher or lower voltages) from the rest of the batteries in your bank--Then that/those batteries are probably beginning to fail and not sharing load current (or starting to overheat).

https://www.amazon.com/gp/product/B019CY4FB4 (example of AC+DC current clamp DMM--Mid priced)

With the current supply chain failures/shortages--There is the issue of buying batteries know (or getting them on order)--Or seeing what happens down the road for availability....

-Bill "no crystal ball available" B.

Photowhit · October 2021

wellbuilt said:.
I would love to get some 2v cells or forklift battery’s my self but the Golf cart batteries are Inexpensive 16 for 1500$

There are costs and then there are cost. I paid $2525 delivered, for my 24 volt 660 ah forklift battery, It would cost very close to that today. It's 10 years old. (Here's a link, they over estimate the 20hr capacity, calling it 804ah, 660 is more realistic)

Forklift Battery Price List - GB Industrial Battery (gb-battery.com)

To answer a couple other questions, I would have gone to 48 volts, but this is all my cabin would ever need, then they changed the covenants! Which answers another question, how do you move an 1100 pound battery? Slow and steady, I moved it myself with leavers, fulcrums and ramps, onto and off of a trailer (rated at 1000 lbs) with a tiny Toyota Echo.

It's 10 years old and at the end of it's life. It was 'poisoned' early on, I was working security and someone stuck something in one of the cells. Nothing to ugly happened but the electrolyte was always dark. after about 3-4 years that cell became the worst performing cell.

Some people have gotten 20 or more years out of tall case forklift batteries.

I usually only count on 4-5 years out of golf cart batteries. So there is value vs value. I hoped to get 15 years in my plans, but I'll very likely replace it in the next year.

Photowhit · October 2021

It appears Marc's comments about a 48 volt string of 2volt cells has the added advantage of being able to remove a cell and still be 'within the boundaries' of a 48 volt inverter. Perhaps it was in a different thread? Marc has a lot of background having sold batteries for off grid systems for a long time. Hope nobody pissed him off... He's a valuable asset here!

wellbuilt · October 2021

I hope he isn’t mad ?

All of you guys are the big dogs in the thread , I’m just a little puppy .
You have all helped me immensely .
I’m just trying to give back to the forum and help where I can with out giving out bad information .
I’m good at a lot of things but solar /battery systems just is not one of them .

wellbuilt · October 2021

Potowhit, your battery looks real good and I may go that way in a few years but I would need a larger battery in 48 volts.

I’ve been building my place out of pocket and real off grid battery’s just weren’t in the cards at the time .

The GC battery’s seam to be holding up good I’m still close to full capacity . So we will see how it gos

Marc Kurth · October 2021

Photowhit said:

It appears Marc's comments about a 48 volt string of 2volt cells has the added advantage of being able to remove a cell and still be 'within the boundaries' of a 48 volt inverter. Perhaps it was in a different thread? Marc has a lot of background having sold batteries for off grid systems for a long time. Hope nobody pissed him off... He's a valuable asset here!

Thank you, but no, Sir. The OP pointed out that I was diluting his post. He actually was right, and not wanting to be "that guy", I removed my off-topic comments. No harm, no foul.

swollen 6v interstate batteries

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