How to extend Battery Bank time of failure?

Sakamochi

This is the next chapter in a series of battery bank failures. The last episode was seen here as "Early Battery Failure" (2018) and "Boiling Mad". 

I keep my batteries in pristine condition. Distilled water always. Filled monthly. Tops are always clean and dry. Posts are spray coated 3 times a year, look brand new. Never any corrosion. The battery box is in an insulated shed. Battery box has powered thermostatic venting fan pulling in cooler outside air and exhausting to outside. I  EQUALIZE BATTERIES once a year, in March when the Solar array is cold enough and there is enough sun to generate enough voltage (from previous forum - yes, this array cannot raise its voltage that high when they are hot NO MATTER the state of charge of the battery bank, but that does not matter here in this problem, suffice to say that Equalizing is not the root cause). And the SG's on the Deka batteries stay really well in line with all of the cells. I have data....

Problem:
My positive posts are visibly distending the battery cases upward now, noticed this recently. This has happened in prior battery sets. Also, the electrolyte became "grey" to almost black at the top of the cells in the heat of the summer with carbon "string wisps" seen while taking SG's. This has happened in prior battery sets. The electrolyte appears clear now - the temps are 40 F and below. From my experience, it is very probable that the symptoms seen this summer (and in the past batteries summers) will sometime in the next 9 months result in a catastrophic failure. As for now Voltages and charging times are normal, nominal, no changes. Water use went way up this summer as it was the hottest summer in my records - had 116 F air , battery box in core (between battery cases 4&5) got to 113 F.  I keep detailed records of everything including the ounces per cell). The SG's are about perfect - delta 0.015 between all cells (48).  I would really like to find a way to extend the life of my $5,000 battery bank for more 5 than 5 years...so far, $20,000 in batteries...
2007 Trojan L16's
2011 Rolls
2014 Interstate
2018 Deka 

Previous (2018) forum suggestions:
Put the batteries in a cooled water bath (pretty much impossible)
Batteries are being overcharged (??) 
"Heat and sulfation"

I keep thinking that the maybe set points might be too high - overcharging? The last set got a dose of daily Equalization for the better part of a month (that's how I learned about panels internal resistance limiting voltage, so now I manually equalize once a year)
Maybe my now old MX60 is to blame?
But no one has ever come to that conclusion - yet. 

Should I change the charge controller when the Deka's die?

What to do?

Your help is appreciated!

System:

Location: Northeastern AZ 5500 ft elevation. Full sun exposure 6 am to 7 pm midsummer.

48 volt system 16 L16 new in 7/2014 with Battery box with Auto exhaust

MX-60 Charge Controller

Xantrex 5500 Inverter Charger

16 Kyocera 140 watt with Wattsun Tracker

900W Wind Generator

12 kw Kohler Propane Auto Backup Gen installed Dec 2015. It has come on automatically twice ever due to low battery voltage. Batteries are  NEVER discharged below 48 volts in any case.

The controller, wind gen, inverter are all original equipment 2007. The home is occupied 1/3 of the year. (two weeks per month). The power usage average occupied is 5 kw per day, unoccupied is 2.3 kw per day. 

Voltage Set Points MX60
Absorb Time          Float        Equalize Time  
57.6v    2  Hours    54.4         60.4 3  Hours              

BB.

The first guess... In general, early Positive Post Extrusion for lead acid type batteries is made worse by (excessive?) gassing during charging. The oxygen formed during charging (and EQ charging which is defined as "selective over charging").

Keeping Lead Acid batteries "cool" is also helpful...

There is also the converse, where undercharging/over-discharging (low state of charge, over discharging) can cause batteries to sulfate faster--Which will cause "general" bulging of the cases (frequently/more often seen case bulging in AGM and similar lead acid batteries.

At bit more discussion in this thread from 2021:

https://forum.solar-electric.com/discussion/356792/batteries-bulging-whats-up

A new battery bank (possibly LiFePO4 now with charger compatible BMS) would be interesting.
 
However, charging LiFePO4 below ~50F can be an issue. (LiFePO4 are "not great" for freezing and subfreezing banks. And better than FLA for hot weather/banks).

One option (especially if staying with lead acid) would be a Midnite Classic+Whizbang current sensor + shunt. Or other charge controller that supports a "battery shunt" (Schneider?).

https://www.solar-electric.com/mnclassic.html (standard Midnite classic)
https://www.solar-electric.com/midnite-solar-whiz-bang-jr-current-sense-module.html (Whizbang current sensor)
https://www.solar-electric.com/mkb-500-50.html (generic 50mv/500a shunt to mount Whizbang on)

Program the end of charge to 2% to 1% (guess on my and also dependent on battery choice) of bank AH capacity, and less chance of "unintended" over (stop charging when battery is no longer accepting "full" charging current (tail of charging current graph).

Again, no expert here, and there are more options these days for systems that directly monitor/integrate battery charging current/sensing. Better than just "charging voltage monitoring and "absorb timing".

Others here with more knowledge than I should be able to help.

-Bill

littleharbor2

My $0,02,
 Your batteries are over 9 years old. They have given good service up to now. Any more life would be bonus in my opinion.

 I would set my bulk/absorb setting higher. Are there charging specs on the battery?

 For your usage, your battery bank is on the large side. You haven't given battery specs but even on the low side of L-16 amp hour rating (390 ah.) , half that bank, 8 cells, is over 20 kw, which is just about right for your usage. What would your SOC be in the mornings when you are there? FLA batteries need to be worked and charged aggressively enough to stir the electrolyte which helps keep it from stratifying.

706jim

You have about the same amount of solar as my system yet twice as many batteries. Mine were purchased in 2015 and so have given my 9 seasons of service. I just had one battery fail this fall and am now going to run the other string of four L16's with the other disconnected. I posted here as to whether to replace my bank when the others fail with 4 versus 8 batteries and got varying suggestions. I am curious to see how the single string will react to the now higher charging current. (I run 24 volts and average 40-50 amps with occasional excursions in the mid 60's so pretty much within the Trojan manufacturer's rated charging current). My previous set of 12 GC's lasted 19 seasons so I'm a bit disappointed with the life of the Trojans, but that system had far less solar and no refrigerator loads that this one does.
BTW I personally doubt that your 900 watt wind generator does very much charging. These things need a LOT of wind speed to make any significant amperage.
In your case I suspect undercharging is the culprit.

JRHill

You have a lot of battery/batteries for the inverter(load) and the charging sources. For comparison when I used lead I had one bank of Trojan L16s and a possible of 3000 max watts of solar and when on generator in the winter a max of charging of 20aac through the inverter as the charging source. Include the many, many hours of absorb charging which when on a generator is an absolute waste of generator time but it had to be done. After 2 iterations of Trojans over 9.5 years I had to do something as in the OP. This pattern just would not cut it for us in terms of cost and effort.

What I learned over time with all the maintenance records and many hours of battery service was that I was not working the batteries hard enough with that ONE bank, let alone two. Full deep cycle batteries like to work hard (discharge) and play hard (recharge). I was doing everything I could expect for this aspect.

For that reason I went with LifeP04 instead of another bank of lead.. They don't care about my usage and recharging. They don't need or want an absorb. They don't need to be fully charged except to recal the SOC monitor. Then the are all the other advantages. My LifeP04 bank is 3 years old now. I know they are there because I see them but that is about the only attention they get, literally. Lastly, at this stage of the game if something happened to me all the DW has to do is start the generator, fuel it and service the lube.

I'd suggest you consider a change after "$20,000 in batteries." Lastly, I replaced the Trojan RE16s with 4 Simpliphi blocks and with the available depth of discharge can go 2 days. I could never go that with lead. And because of that capacity I can dial back the charging so I keep the batteries between 50 to 90% which is a good spot for LifeP04 for longevity. I hope to not need to replace batteries again is this project.

One last point: at install of the LifeP04 changeover I installed three blocks. I was impressed but it got me to thinking that if I had one fall out I wouldn't want to get by on two - so I added a fourth within the third month. If one failed I could easily get by with three while the gods of warranty consideration debated with me. So one can overdo a lithium bank much more simply than a lead bank and still enjoy the benefits.

SteveK

Yes, huge battery banks with smallish solar arrays or not enough Sun. That is in the realm of Lithium for sure. At least for now....

I know you are in intervention mode right now and this does not help you today. I have no other experience with LA other than needing to replace my GC2 bank once in 12 years, after 6.5 years, while suffering for the last year of each implementation. I jumped chemistries at the same time I resolved to give-up other non-productive things in my life.....things like self-flagellation and shooting John Wick's dog.

Hobbies are great too though and I treated my LA bank as such. Enjoyed the responsibility at first but it got tedious. Respect for those who do enjoy it.

Sakamochi

Thanks for all of the excellent inputs and perspectives, especially BB - you've helped me in the past and I appreciate it. 
Some responses I see as probables, some not. At 5500 ft elevation in Northern AZ sun is not an issue. My house is 2,000 sq ft. Refrigerator, freezer, little vampires here and there average 2.5kw per day bny themselves (no people). Running the heater (always 54 degrees or better inside) and putting people in drive that to 5-7 kw per day occupied. Its kind of a balance: winter- heater/summer refer and freezer run much more so its almost the same average power.  My power system is old (16 years), with low PV power (the panels cost $600 each - 140 watts then!!) They are on a tracker array, so they get as much sun as possible all day. That was the way to make up for expensive panels back then. The DEKA's L16's are 5 years 2 months old (not 9 years old). The batteries see about 30 degrees at the low and 113 at the high in the box. No fixing that more than what I have already done. As far as "bubbling and stirring things up" the batteries do too good of a job of that in the summer. 100% more water than when new in the heat. As far as "my bank is too big" - I beg to differ. We would never make it thru two days without sun. We would have to run the generator. Generator=you did not plan your system right IMHO. My neighbor has the 24v version of what I have, same-same everything except he has to run his diesel genny nearly daily to keep up. His batteries (also DEKA 2V) do last longer that mine (by a year or two), so maybe beating the crap out of them is actually a good thing, I never thought of that idea before. Typical SOC varies: season winter is right around 48 volts, sometimes a little lower, could get down to 47.5v. The generator is automatically step programmed to not allow discharging below 50%, and as I wrote, that has happened twice in ever. I agree that the absorb takes forever on the generator (which can put 35 amps into the bank thru the inverter/charger). I usually quit that when charging in bulk at top end when I know Mr Sun is forecast to roaring back on the next day. Again, that is probably 2-3 times a year, so of no consequence. We go into "conserve power" mode when these winter storms hit and cut sun power for days - no microwave, coffeemaker, hair dryers, etc. The wind generator does really pull its weight, again in the days of high cost PV that was the way to go. Not so anymore. When the wind gen dies, it will not be replaced. No one has parts for them anymore.. We have a BIG solar farm (thirty systems, 300 ft tall, 100 ft blades) just to the west - so we are in the "wind belt". Sustained 900w charging happens quite often, especially when there is those storms without sun. Undercharging? Almost never (storms and/or guests beating up on power overnight could lead to generator needed as previously described)  A usual day starting at 48 volts to completed absorb usually takes 6 hours or less from "wake up".  If we really slam power (lets say 7.5kw for the day) it might take all day to get there on a not too hot all sunny day (10 hours). The PV can hit 16kw in one day if everything is just right. 

I think it might be right to change the whole system out when the DEKA's go. The LifeP04 with all its accompanying parts would likely be the way to go - I'll need some trustworthy tech help to come up with a spec as to what that is for sure. I think this could be had for $20,000. Or maybe, in my 8th decade of life it might make more sense to spend less on yet another set of FLA which may outlast me!

littleharbor2

With over 40kw of battery you shouldn't ever get down to 48 or 47.5 overnight with fully charged batteries based on your usage. Something doesn't sound right.  Either your batteries have diminished capacity or you're not getting fully charged at the end of the day, which can lead to diminished capacity.

JRHill

Sakamochi said:

Thanks for all of the excellent inputs and perspectives, especially BB - you've helped me in the past and I appreciate it. 
Some responses I see as probables, some not. At 5500 ft elevation in Northern AZ sun is not an issue. My house is 2,000 sq ft. Refrigerator, freezer, little vampires here and there average 2.5kw per day bny themselves (no people). Running the heater (always 54 degrees or better inside) and putting people in drive that to 5-7 kw per day occupied. Its kind of a balance: winter- heater/summer refer and freezer run much more so its almost the same average power.  My power system is old (16 years), with low PV power (the panels cost $600 each - 140 watts then!!) They are on a tracker array, so they get as much sun as possible all day. That was the way to make up for expensive panels back then. The DEKA's L16's are 5 years 2 months old (not 9 years old). The batteries see about 30 degrees at the low and 113 at the high in the box. No fixing that more than what I have already done. As far as "bubbling and stirring things up" the batteries do too good of a job of that in the summer. 100% more water than when new in the heat. As far as "my bank is too big" - I beg to differ. We would never make it thru two days without sun. We would have to run the generator. Generator=you did not plan your system right IMHO. My neighbor has the 24v version of what I have, same-same everything except he has to run his diesel genny nearly daily to keep up. His batteries (also DEKA 2V) do last longer that mine (by a year or two), so maybe beating the crap out of them is actually a good thing, I never thought of that idea before. Typical SOC varies: season winter is right around 48 volts, sometimes a little lower, could get down to 47.5v. The generator is automatically step programmed to not allow discharging below 50%, and as I wrote, that has happened twice in ever. I agree that the absorb takes forever on the generator (which can put 35 amps into the bank thru the inverter/charger). I usually quit that when charging in bulk at top end when I know Mr Sun is forecast to roaring back on the next day. Again, that is probably 2-3 times a year, so of no consequence. We go into "conserve power" mode when these winter storms hit and cut sun power for days - no microwave, coffeemaker, hair dryers, etc. The wind generator does really pull its weight, again in the days of high cost PV that was the way to go. Not so anymore. When the wind gen dies, it will not be replaced. No one has parts for them anymore.. We have a BIG solar farm (thirty systems, 300 ft tall, 100 ft blades) just to the west - so we are in the "wind belt". Sustained 900w charging happens quite often, especially when there is those storms without sun. Undercharging? Almost never (storms and/or guests beating up on power overnight could lead to generator needed as previously described)  A usual day starting at 48 volts to completed absorb usually takes 6 hours or less from "wake up".  If we really slam power (lets say 7.5kw for the day) it might take all day to get there on a not too hot all sunny day (10 hours). The PV can hit 16kw in one day if everything is just right. 

I think it might be right to change the whole system out when the DEKA's go. The LifeP04 with all its accompanying parts would likely be the way to go - I'll need some trustworthy tech help to come up with a spec as to what that is for sure. I think this could be had for $20,000. Or maybe, in my 8th decade of life it might make more sense to spend less on yet another set of FLA which may outlast me!

I've read this post a few times. This seems to fall into "The way I've always done it." You might go LifeP04. But even a bank of lead might outlast you at 80 years old. Why go LifeP04?

This might seem rude but are there not people left behind to clean up your 'thing'? Between the soon to be retired wind gen and whatever, have you documented this so someone can follow behind you? At 80 years old do you even care?

If you look at my previous post, third paragraph and last sentence it was about someone continuing on behind me. I have put a lot of time in a system without a babysitter with all kinds of MacGyver things. This is a gift to the DW. She has little to do.

You, sir, are being selfish and silly. 

Sakamochi

JRHill posting is a sad example of the problem with social media artists in a technical discussion. He is the one who is sad, obviously. He cannot do arithmetic either, a person entering their 8th decade is in their seventies. I wouldn't trust his technical incapabilities. He really probably belongs on a social media outlet. I presented what I have going on as a base for changing from the existing older technology to possibly newer technology, and perhaps garnering some ideas about that, but JRHill "didn't get the message" because that doesn't fit his M.O.


So JR - please ride off intro the sunset somewhere....irritate some other social forum there. 

BB.

Please ease up a bit folks...

-Bill "moderator" B.

JRHill

My apologies. This hit a hot button.

Sacamochi, Please accept my apology for being rough. Will you accept my apology?

SumPower

"From my experience, it is very probable that the symptoms seen this summer (and in the past batteries summers) will sometime in the next 9 months result in a catastrophic failure. As for now Voltages and charging times are normal, nominal, no changes. Water use went way up this summer as it was the hottest summer in my records - had 116 F air , battery box in core (between battery cases 4&5) got to 113 F. "

I used to be one of many who worked in an Industrial battery shop with a fleet of 34 traction batteries (forklift battery), We were taught in are training that for each 18° F change in temperature above 77° F, that the battery cycle life could be cut by up to 50%. That was to ingrain in us the importance of closing the bay doors between the conditioned space in the battery shop and the smelting area.

The proof in the pudding was some smaller equipment that only required one battery had remote charging stations that were close to the  smelter environment and the batteries where charged at ambient temps in the summer of over 100° F. These batteries failed at a much, much higher rate than the ones charged in the conditioned space.

 Per our EE, the most important part that was stressed working with these lead acid traction batteries was the temp. of the batteries while charging.

From this on the job learning experience I have always had my batteries in a conditioned space.

Wheelman55

We were taught in are training that for each 18° F change in temperature above 77° F, that the battery cycle life could be cut by up to 50%. 

BB. Let me know if I should start a new thread. 

Sumpower and others. Can you speak to what effect high temps might have with storing lithium batteries?

In our case (Sonoran desert, TX) we shut our system down for the summer months. Temps inside the battery shed likely stay in the 90’s F for most of that time. High temp on the min-max thermometer showed 97 F this past summer (2023). 

With the batteries turned off, self discharge is very small over the 6 months the batteries are stored. 

Maybe using lithium batteries and shutting the system down when away for long periods could be a solution for the OP?

BTW. I too am in my eighth decade🙂

SteveK

I would like to contribute more to this thread but feel it is inappropriate because I have just received my first invitation to join AARP in the mail. 

Marc Kurth

SteveK said:

I would like to contribute more to this thread but feel it is inappropriate because I have just received my first invitation to join AARP in the mail. 

Ahh, a youngster!

BB.

Marc, go ahead and start a new thread if you want to take a deeper dive into:

https://en.wikipedia.org/wiki/Arrhenius_equation

From Wikipedia, the free encyclopedia

In physical chemistry, the Arrhenius equation is a formula for the temperature dependence of reaction rates. The equation was proposed by Svante Arrhenius in 1889, based on the work of Dutch chemist Jacobus Henricus van 't Hoff who had noted in 1884 that the van 't Hoff equation for the temperature dependence of equilibrium constants suggests such a formula for the rates of both forward and reverse reactions. This equation has a vast and important application in determining the rate of chemical reactions and for calculation of energy of activation. Arrhenius provided a physical justification and interpretation for the formula.[1][2][3][4] Currently, it is best seen as an empirical relationship.[5]: 188  It can be used to model the temperature variation of diffusion coefficients, population of crystal vacancies, creep rates, and many other thermally-induced processes/reactions. The Eyring equation, developed in 1935, also expresses the relationship between rate and energy.

This is where using calculus (was a text book problem oh too many decades ago) to come up with the 10C/18F and 2x aging factor using the Arrhenius equation and activation energy.

-Bill

SumPower

BB. said:

Marc, go ahead and start a new thread if you want to take a deeper dive into:

https://en.wikipedia.org/wiki/Arrhenius_equation

From Wikipedia, the free encyclopedia

This is where using calculus (was a text book problem oh too many decades ago) to come up with the 10C/18F and 2x aging factor using the Arrhenius equation and activation energy.

-Bill

Learning the concept of the Arrhenius equation as it related to traction batteries was a real eye opener to me in an apprenticeship program, and the calculus was beyond me at the time. It was just a concept on how to study interactions based on time and temperature. Understood the overall concept but you wouldn't have asked me to be crunching any numbers for you at the time.

 When I went to college it took me a couple tries to get a passing grade in calculus, needed a "B" or better.

"Sumpower and others. Can you speak to what effect high temps might have with storing lithium batteries?

I have very little knowledge about Lithium, other than what I see on the forum. So I will be learning from others here. 

For one, I am thankful for the interaction, the knowledge base and the resources brought together here on the forum.

BB.

Probably beyond my math capabilities now.... The calculus was able to "reduce" the equation (with generic activation energy number) to the 10C/2x aging effect. (the actual number was something like 10.1 degree C or something like that).

In general, charging Lead Acid Batteries (pretty much over 80% SoC), fail in charging efficiency... Down towards 80% efficiency (and 20% into heat)--As the batteries approach 100% SoC and (EQ) Equalization is probably 50% into heat (or more) and 50% or so into electrolysis (generating hydrogen and oxygen gasses from the water/electrolyte).

So, charging Lead Acid Batteries in a warm/hot area gives them the double hit of both high ambient and elevated temperature from charging.

Whereas, Lithium Ion (typically LiFePO4 lithium iron phospate because they are a "safer" chemistry), are usually better than 98% efficiency overall (charging and discharging). So little self generated heat (they stay at ambient instead of--worst case--heating to 55C/131F (max charging temperature for Rolls FLA):

https://www.rollsbattery.com/wp-content/uploads/2021/10/R12-100LFP.pdf



So if you can keep "anything" at 95F ambient or less---Is a big help.

Li Ion with longer cycle and "storage life", running "cooler during all operational phases", no gassing, etc... They have some great advantages.

BIg disadvantages include no charging below (roughly) 50F (Lead acid can cycle below 0F)... Also, Li Ion batteries generally should have a BMS (battery management system) to monitor cell voltage, emergency shutdown for over/under voltage, over current, and such...

Have to go now--But a start.

-Bill

Wheelman55

Bill. I’ll start a new thread. 

BTW. My name is “ Pat” not “ Marc”🙂

BB.

Hi Pat,

Sorry--I was reading the wrong quote block... And still got it wrong anyway. Too many things going on at home, not paying enough attention here at times.

Warmest Regards Pat, and everyone!
-Bill

littleharbor2

BB,
 33,332 amazingly helpful answers and one misnamed reply. I believe you'll be forgiven.
 Happy Holidays to you and all here on the forum.

Wheelman55

Bill. I/we greatly appreciate you and your service to this forum😇

BB.

Thank you guys. Happy holidays to everyone here.

-Bill