Charging efficiency LifePO4

[SunEagle]

I wouldn't if I was you, he claims many things which are wrong and shows has no experience or knowledge of large capacity lifepo4 packs, listen to those who actually use and have installed them over many years. Never float lifepo4, retailers claim you can so they reduce the life span of the cells and ensure return sales after a few short years. They did the same with lead acid, in the early part of the last century, you could get lead acid batteries to last decades becuas they were desinged and built to do that. After WW2, they changed the configuration of the batteries so they would fail after a dshort time.

Another claim of his is there are no dedicated lifeppo4 chargers available, when we produce them and know of 3 others here on Australia that produce and sell dedicated lifepo4 charge controllers. Everyone with real knowledge and many years of experience with this storage chemistry will tell you, charge your pack to 14, then switch off charge. the pack will settle at 13.8v which is where it should be for long life. It's the same with DOD, never go below 12v in your pack, and you will get a very long life out of them. It's not rocket science using lifepo4, just common sense

Unfortunately most of those batteries and chargers are not easily available to us in the States. And what has been made is pretty much low end which is where Sunking has received most of his hands on experience and knowledge.

I am not saying Lifepo4 batteries are not good because they have made a lot of improvements along with the charging systems and seem to be creating a bigger area in the solar energy storage industry. We just have not seen them here in the US as much as you have in Australia.

So instead of you and Sunking throwing **** at each other why don't you both try to see each others side of the story and contribute to this forum instead of turning it into a trash heap.

[Sunking]

Never float lifepo4, retailers claim you can so they reduce the life span of the cells and ensure return sales after a few short years.

To bad the battery manufactures and EV manufactures do not agree with you. You are completely misinformed. A123 recommends Float Charging silly boy. Your POV only applies to Floating at 100% SOC. You can Float at less than 100%.

It is the exact same damn thing as putting two cells in parallel. Apparently Silly Boys doing solar where you are do not require such large capacity packs as us EV and US Solar users. You would have to be a fool not to utilize solar power after the battery is charged with good Sun left. Your way stresses the batteries with micro-cycles.

I bet my batteries are bigger than your. Us EV guys tend to use large batteries silly boy.

[dax]

To the best of my knowledge, lifepo4 is the only lithium chemistry used for off grid in Aus currently, by residential and commercial installers and has been for the last few years and not li-ion. Which in Aus and believe elsewhere is what is used in EV's, although my electric bikes and car all use lifepo4, simply because we import them and it's way cheaper that way.

Yes pack size installs down here are probably small compared to what those in the USA claim, the biggest we've installed is 30000ah x 48v lifepo4 and all in 50amp cells. The majority of installs we do commercially are between 10000ah and 20000ah and off gird homes, 1000ah - 5000ah.

As for charge parameters, the ones we use have been derived from experience and experimentation over more than 7 years of installing lifepo4 systems. If my post had been read properly, it points out why retailers of lithium cells recommended float etc, simply because it is cheaper and more profit orientated to using established lead acid charging, then telling everyone it's cool.

Our tests have shown over 7 years, float your lifepo4 cells, or use any other lead acid parameter and their life drops dramatically. The only fool proof method we've come up with after years of experimenting which keeps cells nicely balanced, bulk charge to 3.5v per cell then stop charging. Set up with a cell voltage censor, which cuts all charge as soon as one cell reaches 3.5v in an off grid 24/7 system, means your cells never get out of balance.

In the commercial retail industry, it's called defining your economies of scale to increase profit growth, through return sales and maintenance regimes. We are constantly getting inquires from those who have installed lifepo4 and are using the recommended charge and discharge parameters given to them by retailers and wholesalers an after a couple of years they are in trouble. In all the lifepo4 installs we've made, the only problems have been one or two bad cells, or when some fool decides to make their own adjustments to the system and stuffs it.

I may not have as much experience with this technology as some here, having only done my first off grid install in 1976, my first full off grid solar install in 1981 and our first lithium install in June of 2007, which was li-ion. Now we do one and two lifepo4 a month, aside along with our earthen home builds, which is all we do now. The demand for earthen and earth covered homes on this continent of extreme climate and bush fires, is growing as they are the only homes that survive a fire ad wind storms of the magnitude we are beginning to see worldwide.

Trying to compare EV with off grid is ridiculous, there is a huge difference between in EV and off grid use. Charging them is completely different in every way. Most EV use li-ion, off grid uses lifepo4. EV packs are charged when not in use so may require a different approach, as they only use energy for short periods of time. Whilst off grid is drawing power constantly 24/7 so requires a very different approach. Things like bottom balancing are stupid for off grid, as energy is needed constantly, so you can never drain your pack or you have no power. Whilst EV can use bottom balancing as they only require energy when in use and never 24/7. EV's like to use as much of the energy as is available, off grid is orientated to 80%, charge parameters are also very different. This thread is not about EV's, so using them as an example is off topic and of no help to those wanting information which has no relationship to EV.

[Sunking]

Trying to compare EV with off grid is ridiculous, there is a huge difference between in EV and off grid use. Charging them is completely different in every way. Most EV use li-ion, off grid uses lifepo4. .

Makes no difference what type, size, or application. All lithium batteries behave basically the same, and no different treatment in charging. Both PB and Li use exactly the same Algorythims a CC/CV. If you knew what FLOAT CHARGE meant, you would know it is CC/CV. The only thing different is the Voltage Set Point. For any Lithium, set it less than 100%.

You are spouting nonsense and if you had basic electrical knowledge you would know that because Floating a Battery is exactly the same thing as putting two or more cells in parallel. Soon as you realize that, you will realize how foolish you are. Charge up 69 cells in parallel to 3,45 volts, is no different than 1 cell on a charger set to 3.45 volts. Once the batteries settle on 3.45 volts, no current flows. Essentially an open switch or OFF. Cheese and Rice that is first year apprentice stuff. You do not even understand basic principles of electricity or have any clue what Ohm's Law is. Let me give you a clue: 0 Volts / X Ohms = 0 Amps every day of the week. I can only hope your brain can wrap around such simple fundamentals of ZERO divided by anything is always ZERO.

Wanna know who puts 69 cells in parallel. Tesla does that's who and they FLOAT CHARGE. Tesla and no EV manufacture allows anyone to fully charge or discharge a cell.

No cheap chargers do not use float charge for lithium batteries, expensive 4 and 5 step Smart Chargers do that. You have proved you have not read one link I have posted from multiple sources.from the Industry who says there is nothing wrong with Floating a Lithium at less than 100%. The top dog A123 Recommends FLOATINGE. Every Laptop, cellphone, EV and most Power Tools FLOAT lithium batteries Only thing special about LiFeP04 is they are a lot more tolerant to over charging than the types. EV, Cell Phone, and power tools which use NCO. LFP can take 3.6 to 4.2 volts.

You are right if you are talking about Floating at 3.55 vpc or higher would stress the cells. It would shorten cell life like any Lithium battery. But we are not talking about Floating at 3.55 or higher now are we. Hold at 3.45 to 3.5, and no problem, as the cell is not full and charge current has stopped.. Even if there is 1000 cells in parallel acting like a charger.

[dax]

If you'd read my posts, you'd know I am not an electronics engineer but a master builder by trade, have engineers and technicians working for me that do all that stuff.

You don't read what people post, just grab a couple of phrases and attack with as much venom as you can. Can't understand what you get out of such infantile disgusting behaviour, it does nothing to the conversation, just makes you look abominable.

That may be the way you talk to others in the USA, but we have more thought for others and their opinions, probably why Aus is a nicer, safer and more caring country, as well as a belief everyone needs to be treated with respect when discussing things. Especially when they may not know much technical stuff and just want to find out something and isn't that what this forum is for.

What I'm posting is for those without a big head and little technical knowledge, that don't want to be abused or bombarded with technical worthless crap, for what they are asking and their knowledge base.

When you float a battery, you put in what the battery loses naturally, but lifepo4 doesn't lose anything other than what is used and in an off grid situation, you'd have your charger constantly switching on and off with float, equalisation and temp controls. Which from our experience and everyone else I know in the industry, is detrimental to them.

Of course with li-ion you may need temp controls as they are so volatile. So it's ridiculous to have float and other settings on lifepo4, as bulk is all you need. The CC/CV is all that is implemented during charge until lifepo4 cells reach their limits, then it stop charging, until the pack drops to 13.6v. With lead acid chargers, you have constantly changing CC/CV, not good for lifepo4.

Lifepo4 does not like to be at full charge the majority of the time, they prefer to be at 50%-75% and using float, equalisation, temp controls, all lead acid parameters, are detrimental to lifepo4 life spans. Which is the reason we designed, build and use dedicated lifepo4 charge controllers. They are not cheap as you claim, without any knowledge whatsoever, further revealing your true colours and veracity. We provide a 10 year warranty with our charge controllers, you're lucky to get 1-2 years with altered lead acid commercial junk.

I'm told by our technicians, our method means the pack doesn't cycle and extends life. It also means in an off grid situation any extra energy coming from the panels can be directed to other purposes. Mobile people use this to heat their hot water supplies, as do some off grid people in area's where they are not getting enough sunlight for solar hot water because of the climate, but adequate sunlight for charging.

The link you provided relates to cells not conducive to this situation and are li-ion, not lifepo4, so are very different. You can't charge li-ion as fast with huge bulk charge as you can lifepo4, unless you want them to explode or burn. Lifepo4 will take huge charges compared to li-ion and not get hot or explode. They are very different chemistries and saying otherwise is ridiculous.

Lifepo4 don't heat up, don't explode and we have tried, even to the point of deliberately setting them on fire, drilling holes into them and putting in 360amp charges into a 500amp pack. We did that with li-ion years ago, when testing our new lifepo4 cells compared to the li-ion cells. No comparison, li-ion is very volatile and incapable of taking big charges, lifepo4 is the opposite and excellent for off grid solar panel use.

Once again you relying on your simple, single chemistry experience trying to force every form of lithium chemistry into the one box and that is light years from the facts. Over the last 10 years, we experimented with just about all lithium chemistries and like the majority of real installers, stick with lifepo4. Because it is safe, reliable and using the right charge system and parameters, will provide long lives well over 15 years.

My personal off grid home lifepo4 pack and our office lifepo4 pack, are now close to 8 years old and according to our technicians, have lost nothing in capacity and ability. I believe we are doing the right thing by our customers and are booked 6 months ahead for lifepo4 installations, that doesn't include our own builds. We have also started to sell to other installers our solar charge controllers and also make a 240v lifepo4 charger, for those mobile, so they can plug into power supplies at camp site etc.

[DanKegel]

You don't read what people post, just grab a couple of phrases and attack with as much venom as you can. Can't understand what you get out of such infantile disgusting behaviour, it does nothing to the conversation, just makes you look abominable.

Unfortunately, several of the resident experts on this board appear to feel that they have the right to trash-talk with extreme prejudice.

It does not reflect well on them, or on this board.

[Sunking]

If you'd read my posts, you'd know I am not an electronics engineer but a master builder by trade,

I know it is very easy to tell you have no knowledge of even basic electrical fundamentals. That is what is so funny about you and makes you look silly. You came to this site for the same reason Karrak came here. TO ATTACK ME. Every post you have made is to attack me, I get it, Karrak brought you here, but I am better at it than you and Karrak.

When you float a battery, you put in what the battery loses naturally, but lifepo4 doesn't lose anything other than what is used and in an off grid situation, you'd have your charger constantly switching on and off with float, equalisation and temp controls.Which from our experience and everyone else I know in the industry, is detrimental to them.

Again you just are proved you do not know what you are talking about. You do not even know the basics of battery chargers and Charge Controllers. You are making this stuff up to cover your ignorance.

You do not even know what the definition of Bulk, Absorb, and Float. You are so ignorant on the subject you are clueless you telling him to do almost the same thing as I am. You said this stupid.

Of course with li-ion you may need temp controls as they are so volatile. So it's ridiculous to have float and other settings on lifepo4, as bulk is all you need. The CC/CV is all that is implemented during charge until lifepo4 cells reach their limits, then it stop charging, until the pack drops to 13.6v.

You Moron you just described a perfect 3-Stage algorithm to charge a lead acid battery. You idiot you are FLOAT CHARGING.

How to charge a Lead Acid Battery? Set Charger to 14.4 volts (CC/CV called Bulk/Absorb stage) ) and charge until current tapers. Then lower voltage to 13.6 volts and Float which is a CC/CV mode.

How DAX charges a LFP battery. Set charger to 14.0 volts (CC/CV called Bulk/Absorb stage) and charger until current tapers. Then lower voltage to 13.6 volts and Float which is a CC/CV mode.

You charge Lithium just like a Lead Acid silly boy. You do not even know you are doing the almost exactly what I said to do. I just bypass the Higher BULK/ABSORB voltage of 14 volts.

What you do not understand is Bulk/Absorb, Float, and CC/CV are all exactly the same thing. No switching on or off, no changes in voltage.

One more clue for you my inexperienced silly boy. THERE IS NO TEMPERATURE COMPENSATION when charging Lithium Ion Batteries. You turn that feature OFF when charging Lithium Ion Batteries You only Temp Comp Pb and Nickel batteries by raising voltage as temp goes down. I am typing slowly so you can understand. DO NOT USE ANY TEMP COMP when charging any Lithium battery. There is only one rule with respect to Temperature when charging Lithium Ion Batteries. No Charge Permitted below FREEZING. If you were to use Temp Compensation charging Lithium batteries would damage them raising the voltage when it gets cold. You are no pro, you are a Fraud.

[karrak]

Makes no difference what type, size, or application. All lithium batteries behave basically the same, and no different treatment in charging. Both PB and Li use exactly the same Algorythims a CC/CV. If you knew what FLOAT CHARGE meant, you would know it is CC/CV. The only thing different is the Voltage Set Point. For any Lithium, set it less than 100%.

You are wrong yet again. One of the major factors along with temperature that degrade all Lithium-Ion batteries is the voltage across the battery. Lithium Iron Phosphate (LFP) fully charged cell voltage is 3.45 volts which is much lower than the other common Lithium-Ion batteries. Lithium Cobalt and Lithium Manganese have a fully charged voltage of around 4.1-4.2volts.

To reduce the stress and increase the lifespan of Lithium Cobalt and Lithium Manganese batteries we can charge them to only 4.0-4.1 volts which equates to an SOC of between 80-90%. Now with LFP batteries an SOC >99% equates to a cell voltage of only 3.45 volts.

Now maybe Mr battery expert you can tell us the mechanisms that cause the degradation in Lithium-Ion cells and how they relate to battery SOC and voltage.

Simon

[karrak]

Dax, I would be interested in more information on your battery charging algorithm for off-grid houses.

From what I can see you charge from solar panels until the first cell hits 3.5 volts them remove the charge current. What end current do you terminate the charge at and under what conditions do you start charging again.

In my case my solar charge controller charges my battery to 3.45 volts (13.8V on 12 volt battery) at an end current < C/50, then stops the charging and lets the cell voltage drop to 3.35 volts (13.4V). The solar controller will supply current to any load and try to keep the battery voltage at 3.35v/cell until the sun goes down.

Very interesting to hear about the earth houses. We built our own Light Earth house. Has amazingly good thermal properties, good with fire as well. We have no need of an air conditioner to keep the internal temperature comfortable.

Thanks
Simon

Off grid 24V system, 6x190W Solar Panels, 32x90ah Winston LiFeYPO4 batteries installed April 2013
BMS - Homemade Battery logger github.com/simat/BatteryMonitor
Latronics 4kW Inverter, homemade MPPT controller

[dax]

Karrak, I'm one of those people who have a mental blank when it come to mathematics, everything else is fine but maths and things like algorithms go way over my head, have made many attempts to overcome it. Even did a course on electronics and computer technology, but after 3 years, was still stuck on the first bit of maths, got it fine each time looked at it, but next day total blank. It has it's bonuses, I can talk to customers about their system in plain simple language they can understand, where our techos get carried away and confuse them with the technicalities. I have all the idea's, put them to our techies and they make them work. When they explain how the idea works, I understand what they are saying, but 5 minute later, their technical explanation makes no sense at all, but I know how everything works in plain language. So I explain the system to people and how to use it, never have any trouble. The majority prefer simple explanations, and we deal with the majority, not deranged minorities.

The charger shuts down completely when a cell reaches 3.5v, then re-starts charging when the pack drops to 13.6v. We balance at 3.2v, after the first couple of charge sequences the pack stays in balance extremely well, simply because energy is constantly being used so the cells never get the chance to overcharge. Without any draw on the pack, it drops to 13.8v, depending on draw from the pack, a cell rarely makes it to 3.5v. So the system is always ready to take in large currents if needed without a stupid ancient slow charge system. When the pack does get to 14v during charge, we find all the cells are so close to 3.5v the charger shuts down charge, not the cell relays.

Built my first earth covered home in 1976, my first off grid installation the same year (small generator/batteries) and first solar powered home in 1981. Since have built many earthen and earth covered homes, including earth covered shipping container homes, which are amazingly simple and cheap to build. My own home is 400sqm, with a 1.5m thick earth roof, window walls 500mm earth/bluestone/granite, other walls at least 3m, double glassed windows and airlock door ways and fully sealed. It sits at 23-25deg all year round, currently it is lightly snowing outside and the temp is -1, inside it is 24deg. We keep our lifepo4 packs at 18-22deg, this is because temp variation has an effect on supply power of the pack and longevity.

[Sunking]

You are wrong yet again. One of the major factors along with temperature that degrade all Lithium-Ion batteries is the voltage across the battery. Lithium Iron Phosphate (LFP) fully charged cell voltage is 3.45 volts which is much lower than the other common Lithium-Ion batteries.

No I am not wrong **. All Lithium batteries charge the exact same way. Just like Pb only the Set Point Voltages change. Said that more than 20 times on this thread if you had bothered to read. Simon you and DAX are only here for one purpose. To harass me you cowards. You recruited dax and some other joker to come here just to do that.

[Sunking]

Karrak, I'm one of those people who have a mental blank when it come to mathematics, everything else is fine but maths and things like algorithms go way over my head, have made many attempts to overcome it. The charger shuts down completely when a cell reaches 3.5v, then re-starts charging when the pack drops to 13.6v.

There lies the problem. If you cannot understand 5th grade math it is impossible to grasp anything electrical. You have no idea how a battery charges. If you did, you would fully understand you are Float Charging your LFP batteries exactly like a Pb battery and the way I do numbnuts.

How do you charge PB aka Flooded Lead Acid?

You set the Bulk/Abosrb (CC/CV mode) to roughly 14.4 volts. When the charger voltage reaches 14.4 volts it lowers the voltage to 13.6 vols in a CC/CV mode with a name called Float Charge. Your battery will discharge down to 13.6 volts at which point the charger will supply all power and hold the batteries at 13.6 volts until the charger is turned off or the sun goes down.

Hows does DAX charge a LFP battery?

He sets his charger Bulk/Absorb to (CC/CV mode)14.0 volts. When the charger voltage reaches 14.4 volts it lowers the voltage to 13.6 vols in a CC/CV mode with a name called Float Charge. Your battery will discharge down to 13.6 volts at which point the charger will supply all power and hold the batteries at 13.6 volts until the charger is turned off or the sun goes down.

You do not even know. Because you do not understand the basics, you think you are doing something different. You do not know Bulk/Absorb, Float and EQ are all CC/CV modes or what that means. I will tel you exactly what it means. YOU FLOAT CHARGE LFP batteries silly boy.

It would be very poor design to not FLOAT any battery on a RE system otherwise it is useless and defeats the purpose of RE. Nor could they be used in EV;s Telecom, data, cell phones laptops, and th elist goes on foerever where Lithium Batteries are FLOAT Charged.

Now get lost before you embarrass yourself anymore than you already have, and while you are at, learn how to count.

[Sunking]

Dax, I would be interested in more information on your battery charging algorithm for off-grid houses.

He cannot answer the question, he has no clue what numbers are or what he is talking about. He is saying to do what I have been doing, Floating Batteries. He just has no Clue what Float Charging or any other charge algorithm is He Balances at 3.2 volts.

[jflorey2]

Trying to compare EV with off grid is ridiculous, there is a huge difference between in EV and off grid use. Charging them is completely different in every way. Most EV use li-ion, off grid uses lifepo4. EV packs are charged when not in use so may require a different approach, as they only use energy for short periods of time. Whilst off grid is drawing power constantly 24/7 so requires a very different approach. Things like bottom balancing are stupid for off grid, as energy is needed constantly, so you can never drain your pack or you have no power. Whilst EV can use bottom balancing as they only require energy when in use and never 24/7. EV's like to use as much of the energy as is available, off grid is orientated to 80%, charge parameters are also very different. This thread is not about EV's, so using them as an example is off topic and of no help to those wanting information which has no relationship to EV.

You're making some odd comparisons here.

Both li-ion and LiFePO4 battery packs are assembled and tested before they are used. That is the time that bottom balancing (in the case of LiFePO4) is done - so there's no issue with an off-grid home (or vehicle) using such a method.'

EV's use as much power as they need. Off-grid may be oriented to 80% - but then so is the Leaf, which has an 80% charge mode that is the recommended normal charge regime.

There has been a lot of learning over the past few years on the use of both Li-ion and LiFePO4 as EV batteries. That learning has ported over into the renewable energy arena - and indeed that's one of the main reason that LiFePO4 is now a valid option for off-grid (and on-grid backup) power.

[dax]

It is very obvious you do not have a clue how battery charges or electricity works. Impossible without simple math skills you are not capable of doing. .

You are so clueless what you are saying, you have no clue you are agreeing with me. Your charger is not Shutting Down when a cell reaches 3.5 volts, it is Switching from One Voltage Set Point to Another Voltage Set Point. Exact same thing any Lead Acid Charger does. You Bulk Charge (constant current) until pack reaches 14 volts, then switches to 13.6 volts for Float a CC/CV mode. You ignorant SOB you are FLOAT CHARGING the battery. You can do that with any Charge Controller made for Lead Acid. You would set Bulk = 14 volts, Absorb/Float for 13.6.

Now get lost before you embarrass yourself more than you have and learn how to count.

The embarrassment is in your corner, you simply refuse to read what is posted and all you can do is throw abuse, so pathetic. Which is why you are so contradictory and hypocritical in your abusive deranged rants. Your ludicrous and hilarious conspiracy claims are so funny, so funny.

Float charging, charges a battery at a similar rate as a battery self-discharges, which maintains a full capacity battery. Our chargers do not do that at all.

During float charging the charger, battery, and load are normally connected in parallel. Float charging is constant-voltage charging, usually less than about 2.4v per cell, which keeps the charging current low and minimises the damaging effects of high-current overcharging lead acid very susceptible to.

Our charges shut down, do not put anything into the pack until it drops to 13.6v. Then it provides bulk charge to 14v and again shuts down completely.