LifePO4 GBS Amp Hour Testing 2.5v to 3.6v per cell

[SunEagle]

I never said that I read all of your posts. Just other posts...



Dude, I'm not trying to attack you. I'm just saying -- from the stuff I have read, you haven't done anything but spout numbers and claims about your experiences and systems and word-of-mouth customers, but haven't backed any of your claims with hard data - no charts, graphs, pictures, logs, websites, newspaper/magazine articles, nothing :/ If I'm wrong and have missed them, please show me, don't just chop me down and call me ignorant. Put yourself in my shoes - would you trust what you're saying based on the amount of third-party-verifiable data that you've provided?

You could be totally legit and on the cutting edge of the technology. But for what it's worth, I could just as easily say that I have a ton of customers and this amazing system, but without something to back it - something - anything - it's just words. So please forgive me for being skeptical, but I don't know you from Joe Schmoe.

If you look at the bottom of karrak's posts you will see the hardware he uses. He has 32 x 90ah batteries that are LiFeYPO4 made by Winston. But he does mention a homemade BMS whatever that is. I am not sure exactly what Dax makes or uses but I would think something similar to the Winston.

[smily03]

How do you know that what Sunking is saying is truthful and correct and that he understands what he is commenting on? Unless you have a technical understanding of what he is writing about you don't. You take it on good faith that he is not lying to you and does know what he is talking about.

You're right, I don't have a technical understanding of it. And I don't understand all of the details and nitty-gritty. And I'm not saying that Sunking is infallible, or that other people's views and experiences aren't true or valid.

What I am saying is that I try to read and understand. I came into this forum mistrustful of Sunking. But I read, and dig, and follow the links that he (and others) post to manufacturer sites and trade sites to see what they're saying, and try to understand what he (and others) say. In a lot of his posts he gives the real calculations that you can do the math for yourself, and look up the formulas for, and see for yourself what he's talking about.

I don't just read here, I read all over the place. And I think that's the key. When other people and sites validate what someone is saying, that gives them credibility.

Sunking's basic beef with LiFePO4 batteries in a PV environment seems to come down to the line of -- they haven't been documentedly around in PV environments long enough to be able to reliably conclude that they have the long calendar and cycle life that some people have experienced. That doesn't mean that they can't, or don't, but just that there isn't the widespread data to validate that to be the case.

It's kind of like, my grandpa's car had over 500,000 miles on it when he finally got rid of it. That was his experience, and it was legitimate. Does that mean that all Oldsmobile cars will get over 500,000 miles if taken care of? Not necessarily. His did. But that doesn't mean that you can safely conclude that all will, based on the experience of one person, or a few people.But if it was determined that a majority of Oldsmobile cars get over 500,000 miles, then yes, it would be a valid conclusion that can be backed by numbers.

The data has to back up the claims. Otherwise, the claims are just that -- claims. But once the data is there to back it up, then that changes the game.

Again, I'm not trying to do anything more than say -- I've followed the hype in the past, and gotten burned. So I'm skittish and more cautious now. I want to believe that there's something better than FLA, both for cycle and calendar life, and lower maintenance. But until there is a good amount of verifiable real-world data to back those claims in this specific application, I'm going to stick to what's known to work. I don't have near enough money to chase fantasy products that don't pan out in the long term.

[Sunking]

I never said that I read all of your posts. Just other posts...



Dude, I'm not trying to attack you. I'm just saying -- from the stuff I have read, you haven't done anything but spout numbers and claims about your experiences and systems and word-of-mouth customers, but haven't backed any of your claims with hard data - no charts, graphs, pictures, logs, websites, newspaper/magazine articles, nothing :/ If I'm wrong and have missed them, please show me, don't just chop me down and call me ignorant. Put yourself in my shoes - would you trust what you're saying based on the amount of third-party-verifiable data that you've provided? .

Smiley he cannot produce anything to back himself up. He has clearly and loudly said he knows nothing about electricity or batteries. He is so ignorant he does not even know he admitted it when he said he DOES NOT COMPREHEND MATH. He cannot even balance a check book. You cannot be an engineer, technician, designer, or even a carpenter without good math skills.

So Dax since because I am such a nice guy and teacher I came up with something that might help you understand Ohm's Law. It is 12 equations and governs what goes on inside any battery. Since you have no math skills perhaps a picture will help you understand.

[Sunking]

As for floating a battery, there is nowhere I can find anywhere on the net that agrees with sunking that a battery disconnected from charge is classed as floating. It is inly floating when a charge is input to compensate for the natural and dramatic lose you find in lead acid.

I rest my case you rhonor. Dax has no clue what Floating a battery is. Even Karrak knows what Floating a battery means

[Sunking]

Yet everything on this site is in the USA including suppliers. Nothing Aus about anything here.

Pay attention, USA is #1.

Let's define Floating a Battery for you. It is something every DC Power person know and is the basic fundamental operation of all battery systems. Soething every pro knows except you Dax. .

Floating a Battery

Holding a battery at some predetermined voltage or SOC and allowing the charge source (rectifiers, power supply, charge controller or whatever) to supply power to the loads while the battery remains floating and ready to take over in the event the power fails or the sun sets on your solar system.

You are micro-cycling your batteries many times a day causing excessive wear. Everyone else knows to Float the batteries and let the solar panels provide power to the loads after the batteries are charged up. You are the only solar person in the world who does not know that. You do not have a clue what is going on and very evident. Not even Karrak will defend you and knows to Float his battery just like I do and have been saying. Karrak is just to stubborn to admit I am right and he does exactly what I say. Charge them up to some point and hold. That means FLOAT. It is just a Voltage that uses CC/CV like any battery charger.

[karrak]

Let's define Floating a Battery for you. It is something every DC Power person know and is the basic fundamental operation of all battery systems. Soething every pro knows except you Dax. .

Floating a Battery

Holding a battery at some predetermined voltage or SOC and allowing the charge source (rectifiers, power supply, charge controller or whatever) to supply power to the loads while the battery remains floating and ready to take over in the event the power fails or the sun sets on your solar system.

You are micro-cycling your batteries many times a day causing excessive wear. Everyone else knows to Float the batteries and let the solar panels provide power to the loads after the batteries are charged up. You are the only solar person in the world who does not know that. You do not have a clue what is going on and very evident. Not even Karrak will defend you and knows to Float his battery just like I do and have been saying. Karrak is just to stubborn to admit I am right and he does exactly what I say. Charge them up to some point and hold. That means FLOAT. It is just a Voltage that uses CC/CV like any battery charger.

Sorry Sunking, you are wrong and you are contradicting yourself in this post. I agree with Dax.

From what I have read, Dax charges his LFP batteries to 3.5V/cell(14V on 12 volt battery) then stops charging and lets the battery discharge down to 3.4V/cell(13.6V) where he starts charging back up to 3.5V/cell again, as you say he is micro-cycling the battery, this is different from floating the battery. The definition you have given states "Holding a battery at some predetermined voltage or SOC" . He is not doing this. Either you don't understand or you are just playing games, which is it?

On the subject of micro-cycling causing excessive wear, from the research I have done I don't think this is the case. The wear on the battery is more dependent on the total number of Ah going through the battery rather than the number of cycles. Doing 10,000 cycles at 9% or 1,000 cycles at 90% gives roughly the same wear even though the amount of energy cycled through the battery is the same. I am happy to debate this and am always interested in getting more information on this subject.

I do not "Charge them up to some point and hold", I charge to 3.45V/cell(13.8V) at an end charge current of C/50 then drop and hold the voltage at 3.35V/cell(13.4V) i.e. I float my battery at 3.35V/cell. If we call 3.45V/cell @C/50 100%SOC, dropping the voltage to 3.35V/cell results in a lower SOC of 99%-98% at the end of the day. From my understanding of the mechanisms that cause "wear" of LFP batteries I don't think my approach will make much difference to the approach that Dax takes. I am happy to be proved wrong about this and am alway interested in further information.

Simon

[karrak]

What I am saying is that I try to read and understand. I came into this forum mistrustful of Sunking. But I read, and dig, and follow the links that he (and others) post to manufacturer sites and trade sites to see what they're saying, and try to understand what he (and others) say. In a lot of his posts he gives the real calculations that you can do the math for yourself, and look up the formulas for, and see for yourself what he's talking about.

As you say, some of the stuff that Sunking posts is very useful and is correct. IMO if all his posts were useful and correct he would be a real asset to this forum, as it is allot of what he posts is wrong and/or oversimplifies some very complex scenarios. If he is challenged and can't defend his statements he starts making personal attacks and/or changes the subject and/or gets the argument bogged down in the meaning of words and terms. This might work well in a political forum but is not really helpful in a technical forum where we are all trying to learn.

I don't just read here, I read all over the place. And I think that's the key. When other people and sites validate what someone is saying, that gives them credibility.

That is great. Just remember that the person making the post is only going to provide links to other information that backs up their point of view.

Sunking's basic beef with LiFePO4 batteries in a PV environment seems to come down to the line of -- they haven't been documentedly around in PV environments long enough to be able to reliably conclude that they have the long calendar and cycle life that some people have experienced. That doesn't mean that they can't, or don't, but just that there isn't the widespread data to validate that to be the case.

If you made this statement a few years ago I would agree with you, but the evidence that LFP batteries will last at least ten years if treated correctly in a PV environment is piling up, Dax is saying that after 8 years he is seeing hardly any change in performance.

If you look at all the posts that he has made they all tell a consistent story. The information in his posts is backed up by posts from Steve G and Barba on this forum who have batteries over six year old, my batteries which are over three years old and a number of others on the Energy Matters forum who have batteries between 3-4 years old. Compare this to Sunking's raves that Chinese LFP batteries are all a pile of crap and will only last two and a half to five years. If I were in court and had to pick who is the credible (truthful) and reliable(provides correct information) witness I would have to choose Dax over Sunking.

Another factor that maybe more apparent in Australia is that there are now a number of large multinational companies selling LFP and other lithium ion batteries in the retail market for use in PV environments. These companies are offering offering ten year warranties on their products.

Simon

[Sunking]

Sorry Sunking, you are wrong and you are contradicting yourself in this post. I agree with Dax.

I am not wrong, Dax is a fraud and you know it.

If all Dax does is let the cells charge up to 3.5 vps, and then switches to 3.4 without letting them saturate first at 3.5 vpc, he is only going to 60 to 70% and you know it for fact.. The batteries have to Saturate, you said so yourself. Dax has no Clue what he is doing. He cannot possible understand he is math illiterate. He cannot balance a check book. He cannot tell the difference between an amp or amp hour. He cannot define what a Watt, Volt, Ohm, or Amp is. He is math illiterate. by his own admission. What part do you not understand?

You are charging like anyone else including myself would charge any battery. You charge to a predetermined voltage, let the battery saturate, then back the voltage off and Float. Simple 2-stage algorithm. of Bulk/Absorb and then Float. Both are CC/CV modes. That is what just about every charge controller made does. Some like Genasun made just for LFP batteries Float @ 14.2, and you know that for fact. So if I am wrong, then you and the rest of the pros are wrong.

[dax]

Pay attention, USA is #1.

Let's define Floating a Battery for you. It is something every DC Power person know and is the basic fundamental operation of all battery systems. Soething every pro knows except you Dax. .

Floating a Battery

Holding a battery at some predetermined voltage or SOC and allowing the charge source (rectifiers, power supply, charge controller or whatever) to supply power to the loads while the battery remains floating and ready to take over in the event the power fails or the sun sets on your solar system.

You are micro-cycling your batteries many times a day causing excessive wear. Everyone else knows to Float the batteries and let the solar panels provide power to the loads after the batteries are charged up. You are the only solar person in the world who does not know that. You do not have a clue what is going on and very evident. Not even Karrak will defend you and knows to Float his battery just like I do and have been saying. Karrak is just to stubborn to admit I am right and he does exactly what I say. Charge them up to some point and hold. That means FLOAT. It is just a Voltage that uses CC/CV like any battery charger.

Thanks so much for proving my point, yes we micro cycle our packs, not float them. It seems you are a complete fraud, or such a pathological liar you have no idea of what truth is and the difference between floating and cycling a lifepo4 pack is way beyond you.

You make all these crazy accusations without any proof and reading other threads you've posted in, you know nothing about lifepo4 or their operational aspects. In fact anyone listening to you, would destroy their lifepo4 with a couple of years. Which you claim is their life span, proving you know nothing.

Karrak is so right, and knows so much more than you will ever know about lifepo4, I listen to what he has to say because it makes sense in the real world and not just in the brain of extremely jealous and inadequate clone.

I'm an honest person, who doesn't try to make out I know more than I do, hence stating I had trouble with the maths. So you try to turn it into me being illiterate, which again shows how pathetic and primitive minded you really are. So I don't understand the maths associated with electronics, considering I've run a successful company for the last 50 years and have done the books for the entire company of 4 divisions for that time, without a qualified accountant and am very well off. Along with bringing forth ideas which have changed the passive home building industry in Aus, established an excellent charge/discharge regime and environment for this century energy storage. Whilst you have done nothing of worth, just follow your simple programming, so there's no comparison, you're a slave. Creativity is way beyond you and that's why you hate those who are capable of inventing things and solving problems with just rational logic, without being an over programmed narrow minded clone and economic slave

You make all these claims without any proof whatsoever and just about every thing you post turns out to be a contradiction or false, when relating to lifepo4 and off grid.

Why this site puts up with you is beyond me, as all it does is confuse everyone trying to learn and they go away thinking this forum is totally stuffed and controlled by an overbearing nutter way past his use by date. Because you are stuck in the last century and have no knowledge of worth outside indescribable confusing babble.

The funniest thing is, you're so stuck in lead acid land you are blind to the massive difference between lead acid and lifepo4. They don't charge the same, you don't float or saturate them, as that will kill then quickly and the proof of that is, when you charge a 12v pack to 14v and it settles back to 13.8v and sits there, the pack it as full as is required for long life and maximum use. If a lead acid battery has that done to it, its voltage will continue dropping because of the primitive technology it is.

You have not one bit of experience in off grid lifepo4, you're a fraud and use your ridiculous semantic babble, to try to fool people into thinking you are right. When you are always wrong on this subject entirely and the thing is your claims relating to lifepo4, you can't back up, because you've never used them for the same period of time that many others have and know how to use them. It's experience in life that counts not out of date 19th century theories.

We have another neat trick which helps balance and keep our packs (not batteries) healthy, we take and charge from 4 points on the pack, not two like ancient lead acid and what a difference it makes.

[dax]

I am not wrong, Dax is a fraud and you know it.

If all Dax does is let the cells charge up to 3.5 vps, and then switches to 3.4 without letting them saturate first at 3.5 vpc, he is only going to 60 to 70% and you know it for fact.. The batteries have to Saturate, you said so yourself. Dax has no Clue what he is doing. He cannot possible understand he is math illiterate. He cannot balance a check book. He cannot tell the difference between an amp or amp hour. He cannot define what a Watt, Volt, Ohm, or Amp is. He is math illiterate. by his own admission. What part do you not understand?

You are charging like anyone else including myself would charge any battery. You charge to a predetermined voltage, let the battery saturate, then back the voltage off and Float. Simple 2-stage algorithm. of Bulk/Absorb and then Float. Both are CC/CV modes. That is what just about every charge controller made does. Some like Genasun made just for LFP batteries Float @ 14.2, and you know that for fact. So if I am wrong, then you and the rest of the pros are wrong.

You really are ignorant and have no understanding whatsoever, your comprehension level is minus zero. Lack of intelligence is your problem, for the last time, we don't charge to 3.5v then switch to 3.4v and I have never said that, we stop all charge at 3.5v. Then we start restart bulk charging at 3.4, if you had the knowledge you would understand why, but you don't. It revolves around wherein the voltage scale of the pack the maximum energy is stored and that is between 3.1v and 3.4v. So by keeping micro cycling the pack, we never effect the knees of the charge regimes and so keep our packs outside a regular cycle, no float just recharge. This extends life and keeps the pack in what we call the sweet spot, not discharging into the knee and not being floated to the detriment of the packs life.

[smily03]

I think I can see both perspectives and sides from what you just said there, and I think that you're *technically* saying the same thing, aren't you??

If I charge a battery to 3.5v, and then shut the charging circuit off until it goes down to 3.4v -- how is that different, in a technical perspective, from charging to 3.5v and then setting the charger to 3.4v?

I understand that shutting the charger off is physically different than just leaving it on but at a lower voltage, but isn't it technically doing the same thing?

[SunEagle]

I think I can see both perspectives and sides from what you just said there, and I think that you're *technically* saying the same thing, aren't you??

If I charge a battery to 3.5v, and then shut the charging circuit off until it goes down to 3.4v -- how is that different, in a technical perspective, from charging to 3.5v and then setting the charger to 3.4v?

I understand that shutting the charger off is physically different than just leaving it on but at a lower voltage, but isn't it technically doing the same thing?

It is a matter of perspective and history of what people feel is the right way or what could be the "old way" or wrong way of storing energy.

I still measure things by what is the most cost effective way as well as what is the best way to get the most out of what I purchase. I still don't know what that is and I do not feel those in this thread have given me enough information to make that decision. Most of it has been IMO hot air and bragging based on their own personal experience.

I will say that while LFP may be a possibility for long term energy storage until I see big organizations or those with "deep pockets"start to invest and build some big installations using that technology as far as I'm concerned it is just another lab test.

[karrak]

If I charge a battery to 3.5v, and then shut the charging circuit off until it goes down to 3.4v -- how is that different, in a technical perspective, from charging to 3.5v and then setting the charger to 3.4v?

I understand that shutting the charger off is physically different than just leaving it on but at a lower voltage, but isn't it technically doing the same thing?

What Dax is doing is charging to 3.5V, stopping the charging and letting the cell voltage drop to 3.4V, then when the cell voltage hits 3.4V restarting the charging until the cell voltage goes back up to 3.5V. This sequence is repeated and causes the voltage to cycle between 3.4V and 3.5V. This is very different from charging to 3.5V, letting the cell voltage drop to 3.4V and then keeping it at 3.4V by providing extra charge if need be.

Dax's charging method results in pulses of charging current going into the battery. The "floating method" means that very little current will be going into or out of the battery while the source charging the battery can supply enough power to supply any loads connected to the battery.

I think that Dax's charging method will mean the battery will spend less time at higher voltages which should mean it will last longer. The "floating method" will result in less charge being cycled through the battery which is also good for battery life. The big question is which method is better?

Simon

[smily03]

This might be my naiivety, but wouldn't that be similar to PV in general? I mean, the sun doesn't shine 24x7, so even if a "float" voltage was set, it would stop "floating" when the sun goes down, then restart the next day. Maybe the self-discharge of LiFePO4 would mean that batteries might not get back down to that 3v4 setpoint overnight if they're not being used, so the charger would stay off longer with dax's method?

Anyhow, I thought that short-cycles were bad for batteries? Maybe not LiFePO4 though?

(Just asking questions to try to lean and wrap my mind around it all... :P)

[karrak]

This might be my naiivety, but wouldn't that be similar to PV in general? I mean, the sun doesn't shine 24x7, so even if a "float" voltage was set, it would stop "floating" when the sun goes down, then restart the next day. Maybe the self-discharge of LiFePO4 would mean that batteries might not get back down to that 3v4 setpoint overnight if they're not being used, so the charger would stay off longer with dax's method?

You are right that the charge controller cannot float charge the battery at night. With most off-grid power systems there is always a load on the battery even if it is just the charge controller. Usually it is much more than the charge controller and includes things like fridges etc which will use a reasonable percentage of the energy stored in the battery each day. If you are not going to be using an LFP battery for some time you should discharge it to around 50% and then disconnect everything from it. This is in stark contrast to lead acid batteries which should be float charged whenever possible.

Because of the loads, Dax's method will be doing short cycles throughout the day. The floating method might subject the battery to higher voltages for a longer period of time but will not short cycle the batteries unless the battery load is more than the PV panels can provide. If you are going to float an LFP battery it is important to use as low a float voltage as possible.

Anyhow, I thought that short-cycles were bad for batteries? Maybe not LiFePO4 though?

For lead acid batteries anything below fully charged is degrading them because of sulphation and other factors. Short cycles are taking the battery below being fully charged. LFP batteries don't have the same issues.

Simon