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

[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.

[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?

[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]

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 .

[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.

[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

[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

[Sunking]

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.

People need to stay far away from you and your biz because you know nothing. about batteries and electricity. You do not even know what you are saying.

[Sunking]

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??

Yes and he is to ignorant to know what he is saying.

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?

The exact same thing, If Dax could comprehend math, he would know that. Dax is Math Illiterate and cannot comprehend

[Sunking]

Dax there is absolutly no difference between charging a Lithium Battery and Lead Acid Battery. Both use the exact same chargers period. The only difference is Voltageg Set Point, they both use 14.4 and 13.6 volts.
I am suprprise dno one has called you out. It you stop Charging as soon as any cell reached 3.5 volts without Saturating, then you are only charging to roughly 50 to 70% SOC. What a Joke? You are a SCAMMER and a Fool. Even Lead Acid Batteries must Saturate just like LFP.

You can Karrak both came here for one reason Only. to bust my chops and looking for trouble. I will always be gratefful and thankful for that because I will; tear you both apart as long as you stay here. You came here looking for trouble, the Moderators approve of it. and I am more than happy to engage and expose. frauds. Dax you are a Fraud.

[dax]

Bala, luckily, lifepo4 does away with water, acid, smell, volatility, weight and energy waste to a great degree. No matter what the last century know it alls say, lifepo4 is nothing like lead acid in charging regimes and methodology and you can see that because they have no experience whatsoever in using them in off grid or mobile systems.

Nows when you need to forget your lead acid programming we all have, as it gives a totally false impression of what this technology is about and how it works. It's natural, lead acid in all its variations, is all we've known for the last century at least and the only real available system for storing electrical energy. Lifepo4 and all lithiums are very different in every way and they come in a number of different chemistries, some say suited for different jobs. The only one really suitable for off grid, RV, Marine and stand alone backup that's safe, reliable, long life and cost effective, is lifepo4. Lifepo4 charging regimes are different again to other lithium chemistries and use different voltages.

Unlike lead acid, you store your lifepo4 system in one or more cabinets, depending on size. You may have 1-4 draws, or doors which hold your packs and charge controllers/BMS. It can be in your lounge kitchen, or anywhere else, there's no noise, smell and everything is safe. We control our own system without outside environmental controls (peltiers), as our house is an earthen passive home and sits at between 22-25C all year round. Lots of our customers don't have environmental controls, their homes are passive so theres no need. It's mainly for those areas which have really dramatic temp changes over 24hrs, or those who still persist in putting their storage outside.

Never float or us absorb, temp controls or any other form of charge other than bulk charge to 14v then switch off charge completely. If you want 2-5 years out of lifepo4, use the lead acid charge regimes and you will get it. Once you see what these things can do for you, you never want to go back, we personally use lifepo4 exclusively in everything now, except laptops.

Lifepo4 can take huge charge inputs without a problem and no get hot, unless you are using large cells, (over 50amp) and they are housed in plastic which is what all the retail ones are. Industrial cells are housed in metal, so any increase in heat in a rogue cell is dissipated quickly. We've tried to burnt them fully charged (3.5v), shot at them, crushed, cut in 2 and the only time anything happened was when we drilled into one and a spark from the metal casing suddenly sent a stream of smoke from the drill hole. By covering the cell, the smoke stopped. The cell buckled and was useless.

Nothing wrong with using your 24v system, it's the charge regime that counts, not the configuration. DIY's have to stay below 50v in Aus, or you require an electrician to do the work. In most homes we stick with 12v, as they are the cheapest components compared to 24-48v and do the job. A 3000w inverter in 12v, is less than half the cost of 24v to buy and we have customers who have 3-4 inverters of various sizes, feeding different circuits in the house. For LED lights, you only need 100-300w for the entire house lighting system. As an example, one light circuit of 300w, two power outlet circuits with 1000-1500w and a 1500-2200w for white goods, all PSW.

You can set up a very simple charge control system with a single stage bulk charger, an 8 cell voltage alarm you can get on ebay for $20 set at 3.5v and a cut off relay. Two more relays and 2 low voltage alarms, one set at 13.4v to switch on charge and the other at 12v to switch off load. To balance all you need is a 3v globe so you can drain any cell line that goes over 3.5v and balance your pack, from their it should function well. To connect your cells, use a ladder configuration and copper bars, not those flimsy connectors they sell that are very prone to energy lose and very costly.

It may not be long before you see in Aus a new set up we are experimenting with, which uses super capacitors. They store and use the days energy input, top up the lifepo4 pack and use what's left to run the house, then switch to lifepo4 when their energy is used. This means your pack may not get used for days or weeks, extending the life, also doubling your capacity and super capacitors can take large inputs quickly. We have a a 40ah x 12v pack we are testing with this method and it works, but is a long way from usable on a large scale and the controls have yet to be fully worked out.

Those who know this technology and are not just stuck way back in the last century, understand how they work and store their energy. The majority of usable energy is between 3.1 and 3.4v, above or below that is very very minimal usable energy, so at 3.5v you are getting 85% of the energy capacity. Which keeps your cell in a good state and doesn't effect the life of the cell. To prove this all you have to do is charge a cell to 3.5v, then watch how the voltage drops and you will see a rapid drop to 3.4v, a very very slow drop to 3.1, then quick drop to 3v. You can charge the cell to 4v and drain to 2.5v, and see the dramatic difference in voltage drop rates between the two different parameters.

One of the bonuses of lifepo4 is all the usable energy is above 12v, so there are no worries about using low voltages so can supply your loads with constant above 12v energy.

[Sunking]

Bala, luckily, lifepo4 does away with water, acid, smell, volatility, weight and energy waste to a great degree. No matter what the last century know it alls say, lifepo4 is nothing like lead acid in charging regimes and methodology and you can see that because they have no experience whatsoever in using them in off grid or mobile systems.

That is pure fantasy, and proof you have no idea how to charge a battery. Charging regimes as you call it as a DIY, professionals call it Algorithms some you cannot wrap your mid around because you are MATH ILLITERATE. There is absolutely no difference when it comes to charging both batteries. They both use the exact same charging Algorithm and Voltage set point.

How to Charge a Pb and LFP Battery:

• Select an appropriate size charger, C/10 is perfect for both.
• Set Bulk/Absorb voltage to 14.4, 28.8, or 57.6 volts to obtain 100% SOC for either battery type.
• Apply Bulk/Absorb until charge current tapers to C/20 to C/33. Dax this is above your skill level, but the rest of us know what C/33 means. It means 3 amps for every 100 AH of battery. So if it is a 100 AH battery. you apply voltage until the currents tapers down to 3 to 5 amps. At that point the battery is fully charged up, both Pb and LFP.
• Once battery is fully charged you can either terminate the charge, or lower the Voltage which is called FLOAT. You Float LFP and Pb at 13.2 to 13.8 volts per 12 volt of battery. Floating is what Solar Folks want, or anyone with emergency standby battery systems. It allows you to hold the batteries charged up, and use solar panels power to be used while the Sun is Up and shinning. That way you utilize Sun Power when it is avaiable, and minimize stress and charge cycles on your battery system for long life.

Nows when you need to forget your lead acid programming we all have, as it gives a totally false impression of what this technology is about and how it works. It's natural, lead acid in all its variations, is all we've known for the last century at least and the only real available system for storing electrical energy. Lifepo4 and all lithiums are very different in every way and they come in a number of different chemistries, some say suited for different jobs. The only one really suitable for off grid, RV, Marine and stand alone backup that's safe, reliable, long life and cost effective, is lifepo4. Lifepo4 charging regimes are different again to other lithium chemistries and use different voltages.

There is the CRUX of your problem, and why you have never learned and never will, you are MATH ILLITERATE. It you understood Algorithms you would understand Lithium Batteries use the exact same Algorythims as Pb. LFP uses exactly the same voltages as Pb. Just like Pb batteries, lithium does use 3 different voltages depending on which type the Anode and Cathode material is made from. 2.9 vpc for LTO, 3.6 vpc for LFP, and 4.2 for NCO and LMg

The only thing that changes is the VOLTAGE SET POINT, the charging algorithm is identical. Look at any high end Charge Controller like Genasun, or a Battery Charger like Elcon one model is for any battery chemistry and voltage. When you buy them you tell them what Battery Chemistry and Voltage you want. Only thing that changes is the VOLTAGE, not the Algorithm.

FWIW there is nothing special about LFP. It has the advantage of being more tolerant to Over Charge which is why DIY's use them because they are safer and do not require special monitoring, That does not mean they are better, When it come to performance, they lack performance thus why commercial EV manufactures do not use them. If you are looking for a perfect Lithium material for Stationary Lithium Storage batteries would be Lithium Titanate aka LTO. LFP has failed in the mass markets. That is why the commercial manufactures like Tesla Wall and Bosch doe snot use LFP for Solar Energy Storage or Motive Power, it is inferior in both applications. Only Chi-Coms make large format LFP cells to sell to the DIY market, not commercial or professionals. Commercial and pros do not use them.

Bottom Line here Dax is you can use any Charge Controller or Battery Charger made for Pb batteries on LFP. Only caveat is the Voltage Set Points are preferred to be programmable rather than switches for AGM, Gel, or FLA. The FLA is fully compatible because the set points are 14.4 and 13.6 volts. Exactly what you want for LFP. They would not work with LiPo or NCO and I doubt you know what that means. To cover all 12 volt Lithium batteries which include all Pb batteries is a Voltage range of 13.2 to 16.8 volts. If you have a 12 volt power supply or charger that can span from 13.2 to 16.8 volts, you can charge ANY 12 VOLT battery on the Market Today and Tomorrow. .They all work the exact same way. Chemistry does not change Ohm's Law which you do not comprehend. If you did, you know what a fool you are making yourself out to be. It makes you a FRAUD.

It doe snot take a genius to figure out you are a Fraud. By your own admission you are Math Illiterate.Anyone with common sense knows you cannot be an Engineer, Designer, Technician, Carpenter, Stone Mason or any profession without being really good at math. Without math you cannot understand the physics. Imagine walking into a place to apply for a job like a Engineer or accountant and tell the Boss you do not comprehend math. They will throw you out of the building. Or go to a doctor who has never studied medicine or chemistry. It is all MATH, and you cannot balance a check book.

[karrak]

Dax, could you give us the technical specs for the batteries that you use. In particular the maximum charge and discharge rates, and the recommended charge and discharge rates.

Does your modulisation go as far as having separate sets of PV solar panels for each battery module?

I am enjoying your responses to Sunking, you have a good way with language. As you have said Sunking's antics don't help with anyone trying to learn anything.

Thanks,
SImon

[Mike90250]

.... we stick with 12v, as they are the cheapest components compared to 24-48v and do the job. A 3000w inverter in 12v, is less than half the cost of 24v to buy and we have customers who have 3-4 inverters of various sizes, feeding different circuits in the house. ......

Unbelievable 3Kw @ 12V = 275A (including inverter 10% overhead) and none have burned ?
How do you manage the 12V distribution in a house, with inverters scattered all over? That's a lot of copper, is it all encased in conduits labelled DC throughout the house?

Just this one comment excerpt is enough to show you as a hack, ready to burn houses down,

[smily03]

Yikes... A 275A load would require a 330A service (assuming standard temperatures and only the two CCC's in a conduit,) which would be minimum 500 MCM copper and several dollars per foot -- it'd be both super expensive and crazy hard to route/terminate/etc... And then finding everything else to handle that kind of load (circuit breakers, etc. ...)

[Bala]

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



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?

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



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

I have a 70 amp charger, approx 2000 watts of panels.

Storage wise daily I need approx 1kwh for fridge, 1kwh for freezer and 1kwh for misc. We use more if the sun is good during the day if we are home, pumping water and clothes washing.

My 2 x PL40 pwm charge controllers are synced by another unit but there voltages have wandered a little and they are approx .2V difference. I have them set to try to compensate but they get confused at times and rerun absorb. I would prefer just one controller, there are a lot more options now than 10 years ago,

yes I could set up autostart for the genset.

Summertime temps would be around probably say 25c to 30c. We get a few days up to 35c but not many much over 30c. 12c on a winter night for us is freezing.

Mike, a Dax system would I think have all the batteries and inverters close together and run a/c from there. But i dont like the idea of multiple banks etc running different circuits. It hard enough for the wife to deal with one bank, let alone worrying about many banks.

today the weather is crap, raining and cold ( for us) little sun today so no hot water. When I got home the wife had the generator running charging batteries, heating water, pumping water, clothes washing machine on. I want my system as simple and reliable as possible.