Hello
So, Midnite Solar doesn't have any products for accurately monitoring SOC of LiFePo4 batteries?
The Whizbang Junior should work fine as long as the efficiency setting is correct.
I know it is accurate for lead acid and I think I heard good results for LiFePo4 as well but let's let the folks that have used it respond. I have been working on some other things myself so am not the best to answer.
I think there are actually some posts here that talk about this.
boB
Thank you for the reply.
Midnite's battery capacity meter certainly doesn't seem to be anywhere near what I'd be after, even if it could accept LiFePo4 batteries. I was kinda ogling the Victron Bluetooth battery monitoring systems with their clean, simplistic graphics, and hoping for something similar.
Clearly I need to do a little more research on what the whizbang jr can do. I was lead to believe that I would need one to set up current limiting on (each of?) my Classic 150s when I eventually get around to setting up my over panelling expansion plan. So, your understanding is that the W.jr can keep track of battery related stats and display them on the dashboard graphics of the 'local application' software?
Quote from: Offgridiot on February 20, 2024, 06:32:11 PMThank you for the reply.
Midnite's battery capacity meter certainly doesn't seem to be anywhere near what I'd be after, even if it could accept LiFePo4 batteries. I was kinda ogling the Victron Bluetooth battery monitoring systems with their clean, simplistic graphics, and hoping for something similar.
Clearly I need to do a little more research on what the whizbang jr can do. I was lead to believe that I would need one to set up current limiting on (each of?) my Classic 150s when I eventually get around to setting up my over panelling expansion plan. So, your understanding is that the W.jr can keep track of battery related stats and display them on the dashboard graphics of the 'local application' software?
Not sure what graphics you want to see ?
The SOC is something I look at to see what it is at the moment and no graphics are needed for that.
Larry
The Whizbang SOC seems accurate for my lithium batteries. In fact I trust it much more than the batteries own bms supplied SOC. That is because the battery bms in mine don't seem to count smaller currents around half an amp. Also the battery SOC gets way off over many days of partial charging when it doesn't fill up all the way to reset.
The Whizbang doesn't have these problems. Last year which was my first year using the lithiums my batteries shut down when I went by the battery bms SOC . I found out that the Whizbang SOC was the one that was correct and that is what I trust now. The Whizbang will give me the average of all four of my batteries too.
When I posted on a solar group about the SOC on bms not being too accurate more than a few people said " so what's new ?" and that most of them get way off.
Larry
Whiz Bang does a great job on lithium I have been using it for 5 years now on lithium, Additionally, it does a great job in turning off charge and discharge. Shut my inverter down a couple of times based on my low soc setting > i have it on two classics one on first generation still kicking. They are like 7 to 10 years or more years old and can't remember.
I may have to get new fans on one notice it is sounding weird lately.
Quote from: ClassicCrazy on February 20, 2024, 09:07:58 PMThe Whizbang SOC seems accurate for my lithium batteries. In fact I trust it much more than the batteries own bms supplied SOC. That is because the battery bms in mine don't seem to count smaller currents around half an amp. Also the battery SOC gets way off over many days of partial charging when it doesn't fill up all the way to reset.
The Whizbang doesn't have these problems. Last year which was my first year using the lithiums my batteries shut down when I went by the battery bms SOC . I found out that the Whizbang SOC was the one that was correct and that is what I trust now. The Whizbang will give me the average of all four of my batteries too.
When I posted on a solar group about the SOC on bms not being too accurate more than a few people said " so what's new ?" and that most of them get way off.
Larry
Hey Larry
Maybe graphics isn't quite the right word but I just wondered about a readout to provide the current battery SOC. Historical data would also be a nice addition but not imperative. It wasn't apparent from the owners manual or website description that that info would be accessible with any of their equipment.
boB suggested the Whizbang Jr should enable this functionality, so I've been watching YouTube videos about the local application and of course he's right. It's just another example of the frustration I've been experiencing with Midnite so far. I've spent a few days wondering if I made a horrible decision to spend my money with them. The jury is still out but having helpful people such as yourselves is a big sigh of relief. Their owners manual has multiple cases of poor writing and outright mistakes that brought my (questionable) brain to a screeching halt. It seems to have been written by computer geeks, for computer geeks (the section on how I'm going to have to set up the controller to the internet so that I can interface with the local application is particularly stressful but my son (a computer engineer) should be able to help me with that). It would be nice to be able to glance at all of the data on a walk-by basis, instead of having to start my computer, open the app, log on, wait for a few ads to finish playing (okay, I know it's probably not gonna be THAT bad....
Quote from: mahendra on February 21, 2024, 12:08:22 PMWhiz Bang does a great job on lithium I have been using it for 5 years now on lithium, Additionally, it does a great job in turning off charge and discharge. Shut my inverter down a couple of times based on my low soc setting > i have it on two classics one on first generation still kicking. They are like 7 to 10 years or more years old and can't remember.
I may have to get new fans on one notice it is sounding weird lately.
Hey Mahendra
5 years. Awesome! Do you have them set up with the 'Follow Me' software? And do you also use the 'Local Application' for monitoring? I'm curious about the ability of the data logging to separate the specific data from each controller. My understanding (from watching YouTube videos) is that Follow Me gathers info from both, and presents the combined data (the total of the amperage from both controllers) but if I want to see the data separated, can I?
Replacing fans should be easy enough? Seems that user-friendly component swapping was one of the selling points that convinced me to go with Midnite.
Quote from: Offgridiot on February 21, 2024, 03:50:54 PMQuote from: mahendra on February 21, 2024, 12:08:22 PMWhiz Bang does a great job on lithium I have been using it for 5 years now on lithium, Additionally, it does a great job in turning off charge and discharge. Shut my inverter down a couple of times based on my low soc setting > i have it on two classics one on first generation still kicking. They are like 7 to 10 years or more years old and can't remember.
I may have to get new fans on one notice it is sounding weird lately.
Hey Mahendra
5 years. Awesome! Do you have them set up with the 'Follow Me' software? And do you also use the 'Local Application' for monitoring? I'm curious about the ability of the data logging to separate the specific data from each controller. My understanding (from watching YouTube videos) is that Follow Me gathers info from both, and presents the combined data (the total of the amperage from both controllers) but if I want to see the data separated, can I?
Replacing fans should be easy enough? Seems that user-friendly component swapping was one of the selling points that convinced me to go with Midnite.
I will clarify a few things. ( Do you have a Classic ?)
The Classic has a mode that sends data out to MyMidnite pretty much automatically . So the data goes to Midnite server and the only initial thing you need to do is set it up on the MyMidnite site which isn't too hard. From there you can see all your historical data and set up the graph to select exactly which data you want to see.
You only need to plug in a Cat5 cable in from your router to the Classics internet port.
This is the same connection needed by the other software.
One of them is the Local Status app which is from Midnite. It works real time and will also allow you to make changes to settings. No other software lets you write the changes as easily.
But that software is a bit dated and while it works okay it does have a few bugs here and there.
The platform that Local Status app was created on is dated so there is no more development of this app going on.
There is another monitoring program developed by Graham called Classic Monitoring app which is the best for displaying data and it will data log also if you leave your android device on. And as just mentioned it runs on Android phone or tablet and is a free opensource software available on the Playstore . This app will combine some data from different Classics if you want it to .
One thing to keep in mind is that the Classics internet port only lets one connection at a time - so you can't have the Local Status app and the Classic Monitoring app connect at the same time. But this doesn't affect the Mymidnite data which works a different way and will always run.
The Follow Me mode is not software , it is a setting on the Classics so that when you connect two or more of them together by cables , the lead Classic will tell the follower Classics when to go to Float .
If you read about other companies products they also have all kinds of setup frustrations , some which are a lot worse than what you will ever encounter with the Classic. I have had my Classics for many years and the firmware updates have fixed any problems and actually added new features. Bob has just been developing one specifically with features for Lithium batteries which the Classic was not originally designed for.
So you didn't waste your $$ .
Larry
Thank you Larry !
Yes, https://mymidnite2.com/ to remotely or locally monitor your Classic.
You have to enable "Web Access" in that pesky network menu though.
boB
Lots of questions here guys.
But yes to all I think .
To be accurate my classic 150 is just about 11years , my classic 200 is a year younger,
And my calb lifepo4 now with a jk BMS is just over six years and going strong thanks to the whiz bang and classic.
I did monitoring some time back and would check in now and again both on my my midnite and local status app.
They are doing a good job so no need to monitor all the time.There is that occasional shut down and restart like yearly or when values looks weird .
I have follow me set up and end amps(really great for lithium).
From experience also there need to be som frequent tweaking of the bulk/ absorb and float voltages to ensure your lithium are getting a good charge and does not overcharge or discharge during float stage .
But that's what pack BMs like the jk BMS are for.
As I pointed out some years ago I enquired from this forum and NAZ on charge profiles for lithium I took a calculated gamble(lots of research and an engineering background,no expert though)and it paid off.
I do not have the new firmware on my classic . I don't bother to try to load it either because Both my classics are second to first generation from what I know . I think I was mention that those would not be capable of accommodating the new firmware .
I might be going as a poster boy again here for shouting out the Classics but it did a good job even when there was no firmware update or readily available BMS for lithium.
I did bottom balance with no BMS during those times bought the whiz bang to help.
I mentioned before that the only thing missing from the whiz bang is individual cell monitoring but I guess that's no longer needed with all the changes to lithium in solar ,
Because of this I no longer build lithium packs for solar only car audio.
Hope this helps.
If you need my setting I will check this tommorrow and let you know it's been so long that I set those and somewhat forgot sorry.
Quote from: ClassicCrazy on February 21, 2024, 06:01:02 PMQuote from: Offgridiot on February 21, 2024, 03:50:54 PMQuote from: mahendra on February 21, 2024, 12:08:22 PMWhiz Bang does a great job on lithium I have been using it for 5 years now on lithium, Additionally, it does a great job in turning off charge and discharge. Shut my inverter down a couple of times based on my low soc setting > i have it on two classics one on first generation still kicking. They are like 7 to 10 years or more years old and can't remember.
I may have to get new fans on one notice it is sounding weird lately.
Hey Mahendra
5 years. Awesome! Do you have them set up with the 'Follow Me' software? And do you also use the 'Local Application' for monitoring? I'm curious about the ability of the data logging to separate the specific data from each controller. My understanding (from watching YouTube videos) is that Follow Me gathers info from both, and presents the combined data (the total of the amperage from both controllers) but if I want to see the data separated, can I?
Replacing fans should be easy enough? Seems that user-friendly component swapping was one of the selling points that convinced me to go with Midnite.
I will clarify a few things. ( Do you have a Classic ?)
The Classic has a mode that sends data out to MyMidnite pretty much automatically . So the data goes to Midnite server and the only initial thing you need to do is set it up on the MyMidnite site which isn't too hard. From there you can see all your historical data and set up the graph to select exactly which data you want to see.
You only need to plug in a Cat5 cable in from your router to the Classics internet port.
This is the same connection needed by the other software.
One of them is the Local Status app which is from Midnite. It works real time and will also allow you to make changes to settings. No other software lets you write the changes as easily.
But that software is a bit dated and while it works okay it does have a few bugs here and there.
The platform that Local Status app was created on is dated so there is no more development of this app going on.
There is another monitoring program developed by Graham called Classic Monitoring app which is the best for displaying data and it will data log also if you leave your android device on. And as just mentioned it runs on Android phone or tablet and is a free opensource software available on the Playstore . This app will combine some data from different Classics if you want it to .
One thing to keep in mind is that the Classics internet port only lets one connection at a time - so you can't have the Local Status app and the Classic Monitoring app connect at the same time. But this doesn't affect the Mymidnite data which works a different way and will always run.
The Follow Me mode is not software , it is a setting on the Classics so that when you connect two or more of them together by cables , the lead Classic will tell the follower Classics when to go to Float .
If you read about other companies products they also have all kinds of setup frustrations , some which are a lot worse than what you will ever encounter with the Classic. I have had my Classics for many years and the firmware updates have fixed any problems and actually added new features. Bob has just been developing one specifically with features for Lithium batteries which the Classic was not originally designed for.
So you didn't waste your $$ .
Larry
Thank you once again. Between the help you guys have graciously offered, and the YouTube videos, and re-reading parts of the manual that previously made my head spin, I'm slowly getting my head back in the game.
Last year I bought 3 Classic 150s, and hardware, and panels and batteries (LiFePo4 ready-made units) for a significant upgrade on my off grid system. In looking forward (with varying degrees of confidence) to the installation, I've been researching (aka web browsing) and have spotted some newer fancy systems that seem to display all the info I would ever want (total solar input, house loads, battery SOC, etc), on these shiny, colourful graphics screens. I guess I'm like a crow....oooh! I want the shiny thing! It'll probably do my aging brain some good to have to add the KWh figures from 4 SCCs together. I just thought there might be a lazy man's solution the (non) problem.
I'm sure I will be downloading the 'local app' or, more likely, Graham's Classic Monitoring app, and playing with it but don't have much interest in web connectivity so now realize I don't need to concern myself with the MyMidnite stuff.
Your clarifications are greatly appreciated! I promise not to panic-sell my Classics just yet. :)
Quote from: mahendra on February 21, 2024, 07:22:10 PMLots of questions here guys.
But yes to all I think .
To be accurate my classic 150 is just about 11years , my classic 200 is a year younger,
And my calb lifepo4 now with a jk BMS is just over six years and going strong thanks to the whiz bang and classic.
I did monitoring some time back and would check in now and again both on my my midnite and local status app.
They are doing a good job so no need to monitor all the time.There is that occasional shut down and restart like yearly or when values looks weird .
I have follow me set up and end amps(really great for lithium).
From experience also there need to be som frequent tweaking of the bulk/ absorb and float voltages to ensure your lithium are getting a good charge and does not overcharge or discharge during float stage .
But that's what pack BMs like the jk BMS are for.
As I pointed out some years ago I enquired from this forum and NAZ on charge profiles for lithium I took a calculated gamble(lots of research and an engineering background,no expert though)and it paid off.
I do not have the new firmware on my classic . I don't bother to try to load it either because Both my classics are second to first generation from what I know . I think I was mention that those would not be capable of accommodating the new firmware .
I might be going as a poster boy again here for shouting out the Classics but it did a good job even when there was no firmware update or readily available BMS for lithium.
I did bottom balance with no BMS during those times bought the whiz bang to help.
I mentioned before that the only thing missing from the whiz bang is individual cell monitoring but I guess that's no longer needed with all the changes to lithium in solar ,
Because of this I no longer build lithium packs for solar only car audio.
Hope this helps.
If you need my setting I will check this tommorrow and let you know it's been so long that I set those and somewhat forgot sorry.
I'm interested to know more about the end amps and how you set yours up. I see a paragraph in the manual about it but like most portions of the manual, it doesn't have much LiFePo4 specific info. Any info about the settings you settled on that you're willing to share is greatly appreciated, especially as related to the float cycle. I'm in no rush, as I'm probably a couple months away from flashing up the first classic. I've got so much work to do before then.
My batteries are from Power Queen, and the built in BMSs should protect the units from overcharge but I suppose that could lead to some nuisance shutdown scenarios.
That 'poster boy' attitude is exactly what I need from you. Don't apologize for it! ;)
So
Quote from: Offgridiot on February 22, 2024, 08:47:08 PMQuote from: mahendra on February 21, 2024, 07:22:10 PMLots of questions here guys.
But yes to all I think .
To be accurate my classic 150 is just about 11years , my classic 200 is a year younger,
And my calb lifepo4 now with a jk BMS is just over six years and going strong thanks to the whiz bang and classic.
I did monitoring some time back and would check in now and again both on my my midnite and local status app.
They are doing a good job so no need to monitor all the time.There is that occasional shut down and restart like yearly or when values looks weird .
I have follow me set up and end amps(really great for lithium).
From experience also there need to be som frequent tweaking of the bulk/ absorb and float voltages to ensure your lithium are getting a good charge and does not overcharge or discharge during float stage .
But that's what pack BMs like the jk BMS are for.
As I pointed out some years ago I enquired from this forum and NAZ on charge profiles for lithium I took a calculated gamble(lots of research and an engineering background,no expert though)and it paid off.
I do not have the new firmware on my classic . I don't bother to try to load it either because Both my classics are second to first generation from what I know . I think I was mention that those would not be capable of accommodating the new firmware .
I might be going as a poster boy again here for shouting out the Classics but it did a good job even when there was no firmware update or readily available BMS for lithium.
I did bottom balance with no BMS during those times bought the whiz bang to help.
I mentioned before that the only thing missing from the whiz bang is individual cell monitoring but I guess that's no longer needed with all the changes to lithium in solar ,
Because of this I no longer build lithium packs for solar only car audio.
Hope this helps.
If you need my setting I will check this tommorrow and let you know it's been so long that I set those and somewhat forgot sorry.
I'm interested to know more about the end amps and how you set yours up. I see a paragraph in the manual about it but like most portions of the manual, it doesn't have much LiFePo4 specific info. Any info about the settings you settled on that you're willing to share is greatly appreciated, especially as related to the float cycle. I'm in no rush, as I'm probably a couple months away from flashing up the first classic. I've got so much work to do before then.
My batteries are from Power Queen, and the built in BMSs should protect the units from overcharge but I suppose that could lead to some nuisance shutdown scenarios.
That 'poster boy' attitude is exactly what I need from you. Don't apologize for it! ;)
So your end amps can be calculated from your battery specifications most lifepo4 cells I came across is around .05c of the capacity ( in my case that works out to 9 amps from 180ah capacity 16s ).Anything above and cells can hit over voltage and pack over charge leading to battery failure or worst.
For float voltage some battery manufacturers recommend bulk equals float but that's not very practical as that can cause an over charge .Some guys here and over at NAZ forum and DIYSolar forum did extensive testing if I am correct float volts from their test works out to 3.375vdc per cell(works out to around 54vdc to 54.4 Vdc depending on brand).This is the part I think needs a bit of tweaking as I have experienced it with several batteries some of them are ;my calb,Rept,rept,eg4,fortress,lishen and some others there are so many now.
Most reputable manufacturers would have these setting in ranges for premade batteries like the eg4 and eg4 for expample if I recall correctly are 54vdc +/- 0.02 .So my take on this the float part is the most troublesome because if you don get this one exactly the battery can slowing discharge or slowing over charge.
Bms doesn't help much here.If the battery is slowing overcharging then the bms will go into alarm with out doing a good balance.The only other thing that would safe guard you is you load and the night(no charge )if your grid connected or have wind that may not be so.Sounds scary but very manageable.
Another experience is most bms have very little balancing power most I think is around 650ma if you are charging to almost full capacity which I noticed most premade (eg4/fortress etc) are doing based on their spec sheets and manuals .you will need more than 650ma balancing power . I don't have data to support but I have observed that 1a of a decent balancing power for an average 100ah battery regardless of voltage this is why I switched to the JK bms from the 123bms the come in up to 4amps of balancing power .If you can increase that it's better but think there is also a cut off point as to how much balancing amps you can apply to your battery with causing an imbalance from too high balancing amps.
The other observation is that the added balancing amps come in nicely as the battery ages. Since I added the jK bms I notice my battery pack is always nicely balanced regardless of the load or charge I have 4amp balancing on them.
Additionally , I use the rebulk feature at a setting of 50vdc which works out to 3.125vpc.This also helps with slow dishcharge.
This is just a figure I am comfortable with however.
To close,I am yet to see how the premade batteries stand up to time particularly with handling imbalance from aging.I almost lost my pack because it a poor bms(123 smart bms) and I had no intention to continue with out a good one.
Look up on bms types as well active and passive .Active and smart is better.
Hope this answer you questions
"So your end amps can be calculated from your battery specifications most lifepo4 cells I came across is around .05c of the capacity ( in my case that works out to 9 amps from 180ah capacity 16s ).Anything above and cells can hit over voltage and pack over charge leading to battery failure or worst."
OK, you're making me nervous....
It almost sounds like it would be safer just to disable the float stage, or stop all power at the end of absorption. Why risk damaging the battery (or worse....by which I assume you mean thermal runnaway/fire) just to get storage capacity from 98% to 100% ?
"the float part is the most troublesome because if you don get this one exactly the battery can slowing discharge or slowing over charge."
How much discharge are we talking about here? Wouldn't it be safe to just lowball the estimate at closer to 0.01c of the capacity (if the float stage has to be enabled at all)? I suppose this might lead to balancing issues more quickly? I think each of my batteries' BMSs has their own balancing circuitry to keep the individual cells balanced in each unit, but I was thinking that I would add one of the Victron balancers to my bank to keep the series connected units in good balance.
Thanks again for your help! You've got me thinking about lots of things I hadn't considered. I've started typing a number of different questions for you, and before posting, found the answer almost right in front of me. Sometimes, it's just a matter of figuring out the right question to ask. All the guys here have done a great job of getting me pointed in a better direction. I guess since we're venturing away from the original scope of inquiry, I should look for answers to my new questions in a more appropriate section of the forum....
Watch Off Grid Garage video where he did some battery capacity discharge testing at various voltages . We are talking about LiFePo4 cells.
The conclusion is that you can fully charge but it takes longer at lower voltages. So not very practical for solar where we have a limited charge time .
The most practical charge point for absorb is 55.2v which gets them 95% full at the bottom of the steep curve. That is 3.45v per cell. You will also notice the current they will accept around this point, and since it is quite a bit lower than 3.65v max - you don't have to worry much about over charging a cell.
The bms settings are best if you can pick the point they start balancing. From off grid garage testing point of view it doesn't make much sense to start balancing below 3.45v per cell. If you have a bms without programmable parameters you can't adjust this.
My bms I have set to start balancing 3.45v and 20mv differential. It has to have both of these and you will only see it at the top charge. I absorb time them for about 15 to 30 minutes which I have determined by watching my battery cells and their needs. My monitoring software watches all 16 cells in each battery. I don't use ending amps.
The Float point really is just finding the point where the batteries are not charging but the controller will kick in to supply all the loads. This is around between 53.6 to 54 v. Since the Classic doesn't have voltage sense you just have to watch how it sees the voltage at the point you want it - because it won't be accurate at the float range if you used the tweaks to offset the voltage . The offset is done for the top of the absorb charge point.
Passive bms usually only balance by shunting some top voltage into resistor and more like 70 to 150 mv from what I have read. My bms is in that range . So what I do is I can adjust the point where the cell goes into over volt protection so I set it a bit above the 3.45v . That way it will turn off charging to cells so the small amount of current shunted off has a better chance at balancing. It seems to be working well for my situation.
One battery I installed an active balancer and that is a different story - it will balance cells fast with 4 amps . Unlike the passive balance that does any and most unbalanced cells at once, the active balancer does one cell at a time , moving current from the highest cell to the lowest cell. It gets them in balance much faster.
I think in reality it doesn't matter too much at the lower 3.45v range if the cells are more out of balance because you are staying away from the top critical points and are in the range where you will be getting most of the power out of your cells anyway.
I have notice the balance getting better on my batteries - it takes a long time to do it with passive balancer of small shunt current. Also it isn't worth in my opinion being obsessed with some perfect balance differential - under 80 to 100mv differential at the 3.45v point is probably good enough .
You can of course do more controlled charging to a higher voltage point near maximum 3.65v with controlled current of small amount with passive balancer , or using active balancer , or doing it manually on each cell.
Larry
In this you can see the balance . Battery 2 has active balancer and battery 1 is passive.
Both of the batteries drop their current to near zero as they fill up at 55.2v which is 3.45v.
I think I had 35 minute absorb time and then you see it drop to float voltage.
Quote from: ClassicCrazy on February 24, 2024, 10:45:38 AMWatch Off Grid Garage video where he did some battery capacity discharge testing at various voltages . We are talking about LiFePo4 cells.
The conclusion is that you can fully charge but it takes longer at lower voltages. So not very practical for solar where we have a limited charge time .
The most practical charge point for absorb is 55.2v which gets them 95% full at the bottom of the steep curve. That is 3.45v per cell. You will also notice the current they will accept around this point, and since it is quite a bit lower than 3.65v max - you don't have to worry much about over charging a cell.
The bms settings are best if you can pick the point they start balancing. From off grid garage testing point of view it doesn't make much sense to start balancing below 3.45v per cell. If you have a bms without programmable parameters you can't adjust this.
My bms I have set to start balancing 3.45v and 20mv differential. It has to have both of these and you will only see it at the top charge. I absorb time them for about 15 to 30 minutes which I have determined by watching my battery cells and their needs. My monitoring software watches all 16 cells in each battery. I don't use ending amps.
The Float point really is just finding the point where the batteries are not charging but the controller will kick in to supply all the loads. This is around between 53.6 to 54 v. Since the Classic doesn't have voltage sense you just have to watch how it sees the voltage at the point you want it - because it won't be accurate at the float range if you used the tweaks to offset the voltage . The offset is done for the top of the absorb charge point.
Passive bms usually only balance by shunting some top voltage into resistor and more like 70 to 150 mv from what I have read. My bms is in that range . So what I do is I can adjust the point where the cell goes into over volt protection so I set it a bit above the 3.45v . That way it will turn off charging to cells so the small amount of current shunted off has a better chance at balancing. It seems to be working well for my situation.
One battery I installed an active balancer and that is a different story - it will balance cells fast with 4 amps . Unlike the passive balance that does any and most unbalanced cells at once, the active balancer does one cell at a time , moving current from the highest cell to the lowest cell. It gets them in balance much faster.
I think in reality it doesn't matter too much at the lower 3.45v range if the cells are more out of balance because you are staying away from the top critical points and are in the range where you will be getting most of the power out of your cells anyway.
I have notice the balance getting better on my batteries - it takes a long time to do it with passive balancer of small shunt current. Also it isn't worth in my opinion being obsessed with some perfect balance differential - under 80 to 100mv differential at the 3.45v point is probably good enough .
You can of course do more controlled charging to a higher voltage point near maximum 3.65v with controlled current of small amount with passive balancer , or using active balancer , or doing it manually on each cell.
Larry
Larry ! I could not have said it better !
Quote from: ClassicCrazy on February 24, 2024, 01:06:19 PMIn this you can see the balance . Battery 2 has active balancer and battery 1 is passive.
Both of the batteries drop their current to near zero as they fill up at 55.2v which is 3.45v.
I think I had 35 minute absorb time and then you see it drop to float voltage.
WoW !
Quote from: ClassicCrazy on February 24, 2024, 10:45:38 AMWatch Off Grid Garage video where he did some battery capacity discharge testing at various voltages .
He has a LOT of videos. I watched one where he was discharge testing some cells but without a focus on different voltages. I'll keep looking. In fact, I went to his oldest video and started watching in order (but skipped a bunch I thought were completely irrelevant). Should keep me busy for a minute....
Quote from: ClassicCrazy on February 24, 2024, 10:45:38 AMWe are talking about LiFePo4 cells.
Sorry, I'm still not sure of some of the vernacular. Do you mean raw (?) cells as opposed to ready made units like Battle Born (or Power Queen, like mine) or server rack? Or LiFePo4 cells as opposed to lead acid batteries?
I made the (questionable/regrettable?) decision to buy 8 Power Queen 12.8V 300Ah units for my 24 volt system (mostly because I didn't (don't) have the confidence/knowledge/time to learn to build a bank out of raw cells and choose BMSs and all that), and the BMSs in my units don't have anything in the way of individual cell monitoring accessible to me. So balancing for me is going to be limited to placing a balancer (I think the Vicrton unit) between the two halves of my series-connected bank. I'm interested in eventually learning about the ins and outs of managing an open rack of cells. I figure that when my 5 year warranty runs out, I can open up my units and test individual cell health, and maybe add a Bluetooth BMS setup. Hopefully by then I'll have gained a better grasp of what's going on with such things.
The process for me of typing out more questions has, by itself led to little incremental gains of understanding. Type a followup question to you, answer part of it myself, Google more ideas, erase followup question to you.
I guess my brain is in the bulk stage and a little unbalanced. I feel like I'm at or near the point where I'm about to transition to absorbing the info you've passed along. I found a few more Off Grid Garage videos that talk about this stuff and it's helped quite a bit (I guess having the visuals along with the explanations bumped up the experience?). Thank you for thinking of pointing me toward them.
The conclusion is that you can fully charge but it takes longer at lower voltages. So not very practical for solar where we have a limited charge time .
Quote from: ClassicCrazy on February 24, 2024, 10:45:38 AMThe most practical charge point for absorb is 55.2v which gets them 95% full at the bottom of the steep curve. That is 3.45v per cell. You will also notice the current they will accept around this point, and since it is quite a bit lower than 3.65v max - you don't have to worry much about over charging a cell.
So with my 12.8V units in a 24V system, I'm taking my time extrapolating your help for my situation.
The math is easy enough. Your charge point of 55.2v means 27.6v for me. The concerning point for me is that that also means charging my units at well below the manufacturer recommendation 14.4v-14.6v. I guess I need to reach out to Power Queen to find out about how their BMS handles balancing the cells within their units. Would 3.45v (or lower) even trigger their (internal) balancer? My paranoid tendencies lead me to suspect that maybe their motivations are that they would love me to overcharge them and burn them out shortly after the 5 year warranty runs out, instead of treating them in a manner that would help them last 20 years or more.
As far as worrying about overcharging any cells, I now can see where that could happen if I follow the battery manufacturer's guidelines with the settings in my Classics and/or my inverter/charger. My thoughts are that I should generally follow the advice you here (and Off Grid Garage) are presenting, and every now and then (every 6 months?), either crank up the charging parameters to closer to the manufacturers recommendations for a day or a week, or take the batteries offline (when they are close to fully charged) and finish them off running my generator with the two 40 amp chargers I bought from the company (Power Queen) along with the batteries. These plug-in chargers shut off completely when the batteries are full. Seems like a bit of a PITA but shouldn't take excessively long.
Quote from: ClassicCrazy on February 24, 2024, 10:45:38 AMThe bms settings are best if you can pick the point they start balancing. From off grid garage testing point of view it doesn't make much sense to start balancing below 3.45v per cell. If you have a bms without programmable parameters you can't adjust this. My bms I have set to start balancing 3.45v and 20mv differential. It has to have both of these and you will only see it at the top charge. I absorb time them for about 15 to 30 minutes which I have determined by watching my battery cells and their needs. My monitoring software watches all 16 cells in each battery. I don't use ending amps.
Yeah obviously I can't adjust this. :(
Quote from: ClassicCrazy on February 24, 2024, 10:45:38 AMThe Float point really is just finding the point where the batteries are not charging but the controller will kick in to supply all the loads. This is around between 53.6 to 54 v.
The small amount of info that came with my batteries doesn't refer to a float stage at all. Just bulk and absorb (both @ 14.4-14.6V). It does state a parameter for what it calls "tail current" (6Amps (0.02C)) which is what I'm assuming everyone else refers to as "ending amps". I guess I'm not really sure what the difference even is between float charging and ending amps. Now I'm thinking that ending amps isn't the amps that are applied near the end of the charging cycle but rather, the (adjustable) point at which the absorb charging basically ends. For some reason, I had the former stuck in my head.
Do you choose not to use ending amps simply because you charge at such a low voltage?
Quote from: ClassicCrazy on February 24, 2024, 10:45:38 AMSince the Classic doesn't have voltage sense
As in, it can't distinguish individual cell SOC?
Quote from: ClassicCrazy on February 24, 2024, 10:45:38 AMyou just have to watch how it sees the voltage at the point you want it - because it won't be accurate at the float range if you used the tweaks to offset the voltage . The offset is done for the top of the absorb charge point.
Is this relevant to my (non-open-cell bank) situation? Is "offset" a parameter that can be manipulated with the balance portion of your 'controllable BMS'?
Quote from: ClassicCrazy on February 24, 2024, 10:45:38 AMOne battery I installed an active balancer and that is a different story - it will balance cells fast with 4 amps . Unlike the passive balance that does any and most unbalanced cells at once, the active balancer does one cell at a time , moving current from the highest cell to the lowest cell. It gets them in balance much faster.
So, on another forum, I had been discussing an alternative to the Victron balancer. Again, the balancer I'm talking about is not for balancing individual cells but rather, balancing two halves of a series-connected 12.8V battery bank for a 24V system. The Victron balancer burns (as heat in a resistor?) around 1 amp from the higher side, only after the battery system increases to more than 27V. Victron doesn't say specifically that it's a passive balancer, but can you confirm whether or not (from my description) that it is? The alternative (ANGUI (brand) HC01 active balancer, found on Amazon.com) transfers up to 5 amps from the high side to the low side if the difference is more than 20mV. Apart from the reputations of Victron (solid) and ANGUI (who?), where do you lean on these choices for my situation? The 1 amp of the Victron unit seems like it would take forever to make an impact on four 300AH 12.8V batteries if they wandered a bit higher than the other four.
Quote from: ClassicCrazy on February 24, 2024, 10:45:38 AMI think in reality it doesn't matter too much at the lower 3.45v range if the cells are more out of balance because you are staying away from the top critical points and are in the range where you will be getting most of the power out of your cells anyway.
I have notice the balance getting better on my batteries - it takes a long time to do it with passive balancer of small shunt current. Also it isn't worth in my opinion being obsessed with some perfect balance differential - under 80 to 100mv differential at the 3.45v point is probably good enough .
You can of course do more controlled charging to a higher voltage point near maximum 3.65v with controlled current of small amount with passive balancer , or using active balancer , or doing it manually on each cell.
This alleviates
so much of my stress! I can't thank you enough. Trying to sort through the opinions, and the
actual importance of many of the details is a thing. I obviously care foremost about the safety factors (....overcharging leading to a fire?), and then system health (....but there's varying degrees of that concern. Overcharging leading to the battery bank failing within 1 year? OOF! Overcharging leading to it failing within 18 instead of 22 years? Meh.). You and the other helpful guys are to be commended for your input here. You're why the internet was invented.
I feel less like I'm sinking, and more like it's sinking in. Slowly, but....
P.S. I hope this (very long) post to your excellent response doesn't scare you off. :-X
Now, back to the cat videos! LOL
You are worrying too much .Power Queen already have BMS .
The seem to be doing a decent job as well so not to worry.
I have been fondling with redodo,chins ,eco worthy ,some other brands,I can't remember and Ampere time they all seem to do ok to good not excellent like the top tier brands that you mentioned but the work ,Some are better than others though.
Your focus should be following the manufacturer's charge and discharge parameters .
Some word of comfort; I saw calb cells gasses on more than one occasions because a guy was too stubborn to put a bms on his pack and misinterpreted the manufacturers charge profiles and recommendation ; He charged his pack to 3.65v per cell every time with no bms ,no balancer and no top or bottom balancing .
It took two years for the overcharge cells to gas and got swollen.He didn't have a fire as yet but I trust that he may eventually.He just replaced the damaged cells and continue business as normal .
Off grid garage seems to be the lifepo4 Guru,that guys does a lot .You have been to the right place .
yes you are going to have to work with the bms that you have.
LifePo4 I meant that particular lithium chemistry as other lithium chemistries have different charge parameters.
You don't need to worry so much about balancing if you are using the power between maybe 35 and 90 percent because the cells won't show much imbalance at those levels. It is only when you try to squeeze out all the power that you can from the battery that balanced cells makes a difference. Since you don't have a bms that shows cell voltages you won't really know what is going on inside.
I don't remember your original concerns. As I may have said before - you charge to your setpoint where you want - then cells are full. After that , you go to float voltage where it lets the controller supply loads but won't keep charging the battery. That is between 53.6 and 54v for Classic.
They recommend higher charge voltage because it charges the batteries cells faster. If you don't need to do that fast charge - it will charge lower voltage for longer time to get them full.
You are right about Off Grid Garage having too many videos - I just looked and can't even find right now the one I was recommending.
But I found this one that might help
https://youtu.be/xBu7ScAdKrg?si=2vB_ykI2WzYInZcM
So in a nutshell
You have the batteries and bms you have. You don't have to worry about the balance so much unless you are trying to squeeze every amp possible out the battery. If you stay lower than the suggested top charge point you will still be getting up to 90% out of them.
It took me a long time to understand how lithium LiFePo4 behave.
I spent a lot of time watching the actual cells voltages in my batteries. You can't do that so have to just be happy with if you get the power you need out of them.
I worried a lot about the cells being balanced when I got my batteries and didn't understand it all and made videos and posts on forums about it. Now I understand how it works and wouldn't have worried so much.
Here is another video with load and charge test graphs - I started it in middle of video but watch the whole thing if you want
https://www.youtube.com/watch?v=FjZEjmJiqTo&t=1298s
Larry