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

[karrak]

My house is running 240V, 24V 3kw inverter. professionally wired with a 10ka generator and change over switch. if needed I can start the genset from the garage and change over to run the house off the genset. I Purchased and installed all the stand alone system components.

Do you have a charger to charge the batteries from the Generator? If so what is the charger's rated output?

A: if I were to follow a Dax system it would mean making a box and cooling system, purchasing multiple Lifepo4 battery banks and controllers as well as 12V inverters and then mounting and wiring all those. or buying a complete unit.

B: As i already have a working 24V system another option is to put in a 24V lifepo4 bank and just change my charge controller settings and use a float charge, and not worry about climate control for the bank.

Some variations on a theme.

• WIth temperature control: If Dax will supply you with just the 2x12V battery packs in their insulated box with Peltier cooler temperature controller and maybe the battery BMS without the inverter. You hook them up in series and hook this up to your inverter and maybe your charge controller/s.
• Without temerature control: If Dax will supply just the individual cells, or you get some Winston or Calb cells to make your own 24 volt battery. You hook this up to your own controller/s and inverter. If you are in a wet tropical region (Northern Queensland?) am I right in thinking that your average daily mean temperature will be around 25^oC?

I have 2 charge controllers and am not happy with the way they sync so what ever battery system I buy will get a new single charge controller.

Can you give some more details on what is not working with this, what is the size of your solar array?

I need storage of about 3kwh a day, and dont need a lot of autonomy as Im not afraid to run the generator to charge, and if we are not here then the place probably only uses about 1kwh a day.

Is the 3kWh your total daily usage?, if so your usage is about the same as ours. We don't have any generator. Our battery stores ~9.4kWh, if you are happy to run the generator you would only need a ~ 3kWh LFP battery. If my memory is correct Dax's modules are 200Ah@12V (~2.6kWh).

If you have autostart on your generator you could hook it up to something like a Victron BMV-700 Battery Monitor and program the Victron to turn your generator on when the battery gets down to 20%SOC and stop charging around 40%SOC-50%SOC.

Simon

[Bala]

C:

Bala, agree with most of what you say, the discussions on lifepo4 you may not find on the normal net, but within trade and special interest forums. My comments on seeing where we are was in relation to the components available here, like charge controllers, bms and the take up of lifepo4, especially in the Rv industry.

It's the same with DIY, you may not have read some of my posts, where I describe a simple very cheap control system for lifepo4 and the closed systems we install, are for those incapable or not wanting to look inside the box. We supply components and any customers that wants to install their own can do so in what ever way they want, we just don't supply an installation warranty for them. However we do deal in 240v, most of our installs are in new homes we or others are building and by law you can't install a 240v system without proper qualifications.

The days of 12/24v systems are over, it's now 240v off grid with the quality of inverters. In most cases we use 12v x 3kw inverters as the run is less than 30cm and when you take energy from the 4 corners of a ladder pack, you overcome lots of problems.

As for temperature controls, you don't need A/C, just a peltier, thermostatic controls and very well insulated box. We've provided a number of systems in central, Nth Aus, Nth coast NSW and the Daintree, as well as Tas and the Snowies. The thing that counts is how well you insulate your systems, a well insulated box loses very little, so keeping it at the right temp is not that hard. As for the sweet spot in temps, around 20-25C seems to be the best. Sure in warm to hot conditions you can take more energy out, lifepo4 don't like being cold, on the other hand they don't like being hot either as heat is a lose and will slowly deteriorate their life. Lifpo4 don't get hot when charging to any degree you will really notice, that's the bonus they provide over other chemistries, so a nice environment makes life much easier.

If you produce good quality equipment, you don't need to be close to a repairer and as our off grid systems are multiple banks and controller packs, if one component goes down, there are a number of others that will continue giving you adequate energy. Our systems are designed to not fail, unlike many others. If you knew the industry, you'd know the biggest problems come from major suppliers who quote lead acid regimes for lifepo4 and use lead acid controllers and their charge parameters. Their approach will most certainly give your lifpeo4 life spans and performance below lead acid. Ee have also installed lead acid with our temp controls a few years ago and they are still performing much better than stand alone lead acid. Proper environmental controls make a huge difference in storage and use, when dealing with any electrical components and many forget these facts, especially the supposed experts. Don't know of any other installer or provider in Aus that uses environmental controls, except for tesla and they are just bombs waiting to go off when their liquid cooling systems fail.

Thanks for the reply Dax

My house is running 240V, 24V 3kw inverter. professionally wired with a 10ka generator and change over switch. if needed I can start the genset from the garage and change over to run the house off the genset. I Purchased and installed all the stand alone system components.

The only real issue I have with my batteries is the amount of water they use, as they have gotten older they use more. They are slowly dying, sgs will not come up to where they were.

I am as much about convenience as cost over life.

A: if I were to follow a Dax system it would mean making a box and cooling system, purchasing multiple Lifepo4 battery banks and controllers as well as 12V inverters and then mounting and wiring all those. or buying a complete unit.

B: As i already have a working 24V system another option is to put in a 24V lifepo4 bank and just change my charge controller settings and use a float charge, and not worry about climate control for the bank.

C: Or I just throw in another set of lead acid.

I have 2 charge controllers and am not happy with the way they sync so what ever battery system I buy will get a new single charge controller.

I need storage of about 3kwh a day, and dont need a lot of autonomy as Im not afraid to run the generator to charge, and if we are not here then the place probably only uses about 1kwh a day.

Really I will put in what i consider to be the simplest cost effective system i feel comfortable with. At the moment threads like these are providing a lot of info to me allowing me to research further, even if they do at times sadly sink to what I would call a Jerry Springer show level

[dax]

Bala, agree with most of what you say, the discussions on lifepo4 you may not find on the normal net, but within trade and special interest forums. My comments on seeing where we are was in relation to the components available here, like charge controllers, bms and the take up of lifepo4, especially in the Rv industry.

It's the same with DIY, you may not have read some of my posts, where I describe a simple very cheap control system for lifepo4 and the closed systems we install, are for those incapable or not wanting to look inside the box. We supply components and any customers that wants to install their own can do so in what ever way they want, we just don't supply an installation warranty for them. However we do deal in 240v, most of our installs are in new homes we or others are building and by law you can't install a 240v system without proper qualifications.

The days of 12/24v systems are over, it's now 240v off grid with the quality of inverters. In most cases we use 12v x 3kw inverters as the run is less than 30cm and when you take energy from the 4 corners of a ladder pack, you overcome lots of problems.

As for temperature controls, you don't need A/C, just a peltier, thermostatic controls and very well insulated box. We've provided a number of systems in central, Nth Aus, Nth coast NSW and the Daintree, as well as Tas and the Snowies. The thing that counts is how well you insulate your systems, a well insulated box loses very little, so keeping it at the right temp is not that hard. As for the sweet spot in temps, around 20-25C seems to be the best. Sure in warm to hot conditions you can take more energy out, lifepo4 don't like being cold, on the other hand they don't like being hot either as heat is a lose and will slowly deteriorate their life. Lifpo4 don't get hot when charging to any degree you will really notice, that's the bonus they provide over other chemistries, so a nice environment makes life much easier.

If you produce good quality equipment, you don't need to be close to a repairer and as our off grid systems are multiple banks and controller packs, if one component goes down, there are a number of others that will continue giving you adequate energy. Our systems are designed to not fail, unlike many others. If you knew the industry, you'd know the biggest problems come from major suppliers who quote lead acid regimes for lifepo4 and use lead acid controllers and their charge parameters. Their approach will most certainly give your lifpeo4 life spans and performance below lead acid. Ee have also installed lead acid with our temp controls a few years ago and they are still performing much better than stand alone lead acid. Proper environmental controls make a huge difference in storage and use, when dealing with any electrical components and many forget these facts, especially the supposed experts. Don't know of any other installer or provider in Aus that uses environmental controls, except for tesla and they are just bombs waiting to go off when their liquid cooling systems fail.

[SunEagle]

I live in Australia and my lead batteries are now over 10 years old. I would like lifepo4 but we will see when I actually need to replace what I have now.

I have googled lifepo4 in Australia and not found anything that really interests me.

I can buy cells and make my own system or buy one of the high priced self contained units that offer what I consider to be unrealistic life expectancy.

As with the units Dax sells most self contained units have their own special custom made charging and balancing systems. While most offer fantastic warranties, for me they mean little unless the company I buy off is in a nearby town and I expect them to be in business for the life of the product.

I live in the wettest part of Australia, hot and humid. If I stand still long enough I will go mouldy, rust, or both. Im not prepared to have a box of secret stuff that I rely on for electricity that has a "Warranty void is opened" sticker on it.

I also prefer a DIY system as it does not then tie me top that one supplier. But until I stop working I dont have time for lifepo4 to be another hobby,

Another issue is that I have read opposite opinions on what is the best ambient temp range for lifepo4. Dax says around 20c?? and can achive that with an inbuilt cooling system. Where I live I would think the only way i could keep around those temps is with an air con and Im not about to do that so I would also need a better understanding of how lifepo4 survive in higher temps without any cooling system. I have also read they operate better at higher temps?

So I will keep hoping my current batteries last long enough for lifepo4 or something else to be an option I am comfortable with instead of lead.

Thanks for your input Bala. I presume there are both good and bad environments for all battery chemistries.

I am still interested in the LFP that Dax and Karrak talk about so I am hoping that Solar Pete chimes in since he has a few years of hands experience with off grid pv systems .

[Bala]

I live in Australia and my lead batteries are now over 10 years old. I would like lifepo4 but we will see when I actually need to replace what I have now.

I have googled lifepo4 in Australia and not found anything that really interests me.

I can buy cells and make my own system or buy one of the high priced self contained units that offer what I consider to be unrealistic life expectancy.

As with the units Dax sells most self contained units have their own special custom made charging and balancing systems. While most offer fantastic warranties, for me they mean little unless the company I buy off is in a nearby town and I expect them to be in business for the life of the product.

I live in the wettest part of Australia, hot and humid. If I stand still long enough I will go mouldy, rust, or both. Im not prepared to have a box of secret stuff that I rely on for electricity that has a "Warranty void is opened" sticker on it.

I also prefer a DIY system as it does not then tie me top that one supplier. But until I stop working I dont have time for lifepo4 to be another hobby,

Another issue is that I have read opposite opinions on what is the best ambient temp range for lifepo4. Dax says around 20c?? and can achive that with an inbuilt cooling system. Where I live I would think the only way i could keep around those temps is with an air con and Im not about to do that so I would also need a better understanding of how lifepo4 survive in higher temps without any cooling system. I have also read they operate better at higher temps?

So I will keep hoping my current batteries last long enough for lifepo4 or something else to be an option I am comfortable with instead of lead.

[SunEagle]

Well Solar Pete.

Dax has posted some very interesting information concerning LFP battery technology that has peaked my interest.

Since he lives in your neck of the woods can you at least shed some light on what he states that it is the path to a better mouse trap concerning energy storage for solar pv systems?

[dax]

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)

The first thing is to change your mindset and get rid of all the lead acid programming we all have and lose it, because it has nothing to do with this technology or lifepo4 chemistry. Then replace it with, lifepo4 is nothing like lead acid in any way, except it stores reusable energy. All charging and discharging are totally different, as is the way cells accept charge.

As karrak has pointed out, storing a lifepo4 cell is the opposite to storing a lead acid battery, lifepo4 loses virtually nothing over very long periods, if stored at the right voltage. Leave a lead acid battery for a few months and it will have lost about a 1/3 of its stored capacity, whilst lifepo4 and most lithium chemistries will retain it's voltage with no lose.

Lifepo4 accepts charge rates and time lines light years ahead of lead acid and should never be charged to over 3.5v or below 3v, unless you want lead acid life spans. it's the same with using lead acid charge parameters, they will reduce live by 75-85%, meaning you will only get 3-5 years if you are lucky. lead acid absorbs energy very slowly and has huge resistance to charge input, compared to lifepo4. It can takes days to recharge a lead acid bank which has got below 12.2v in an off grid system and many people rarely get to full charge because there is load draw on the bank constantly. A lifepo4 of the same capacity will take a few hours, be used and then recharged to full while being used during one day. It will also give you between 30-50% more energy from the same stated capacity and a less than half he weight and size.

Most are waiting for supposed big business to get on board, so they have some delusionary proof this technology works and they stick with these profit growth corporations like slaves to the slaughter. Yet anyone with just a miniscule working brain knows these corporations rely upon repeat sales, short life spans and maintainance of supporting equipment with short term built in redundancy, to increase and sustain their profit growth. Problem with that is, it's all unsustainable in every way and will be the death of current societies over all within the next 5 years probably

If they build lifepo4 system that lasted 15-25 years, they would have no profit growth and as lifepo4 is easy to repair or rejuvenate, with about a 50% original cost recycle value, last century economics just doesn't cut it for this century. So they have to push claims that lithium is no different to lead acid and has an even shorter lifespan, with lots of problems compared to centuries old technology. Those trapped in the last century will probably never get this new technology, or how to use it. Just like they fail to take up lots of other alternatives and much cheaper approaches to the future. So are desperate to maintain their elitist control, over what they have no control over or working knowledge.

The facts are, lifepo4 is not some far out complicated energy storage system, its very simple and is light years closer to what should be a reasonable energy storage system, compared to centuries old dinosaur storage technology.

For off grid, RV, portable energy, safety, economies of scale and reliability, there is nothing like lifepo4. In fact we believe it is superior to li-ion for EV and that will become apparent over the next 5 years, because of safety and reliability. Of course we may see new lithium storage soon, in the form of Li- graphene, in an Aus university they are getting close to that reality. But if you have a system now, that will give you a return within 5 years, then give you free energy for the next 10-20 years. Compared to short life, polluting, heavy cumbersome and inefficient junk, It's a no brainer

Anyone interested in what is happening in Aus, just do a search of lifepo4 installations in Aus, you may be surprised at how advanced we really are, compared to those clinging to the past.

[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

[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]

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

[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.

[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?

[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.

[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.

[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.