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

[dax]

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,

Now what can anyone say to something so infantile, ludicrious and stupid as what you've posted. Or is it you have no real life experience outside an office or school room and no clue of what or how a real off grid lifepo4 system works. It's plain to see you've not read my posts, just jump on the band wagon in a childish attempt to beat your sagging chest.

However just to amuse you, a 3kw inverter, would never draw 275amp at once or constantly. In an off gird system it would be lucky to get over 1.6Kw at any one time and that would be a large appliance starting draw. I've posted many times, our installations are 240v wired and for the ignorant, that means inverters are situated in the module, connected within 10-20cm of the controller above the pack, or bank. They then connect to each 240v circuit in the house, if you can understand that complicated explanation, or is plain simple understandable language beyond you.

[dax]

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

Our cells maximum constant charge current is 75amp, discharge is 150amp and max burst discharge is 250amp.
We use 750w x 24v of panels per 60amp controller, most installations of ours are 1000-2000amp lifepo4. Passive homes don't use much energy and have between 3-6kw of panels so 4- 8 controllers into 2-4 x 500amp lifepo4 packs. Some use the packs separately through individual inverters and some use them in a parallel bank through one inverter, personally prefer a number of inverters to make the system more fail safe and that's the way we are heading.
We build fail safe systems, if one set or component goes down, the rest can carry on providing energy.

I'm just an illiterate mate, can't spell, read, write or add up, according to some. The problem with deranged ideological egotists is, they are so far up themselves they don't have a clue outside their simple controlling programming. Creativity and lateral innovation is way beyond them, all they can do is repeat their imbedded mantras of I'm right and everyone else is wrong, no matter the facts.

What these idiots fail to grasp is the majority of those looking for information regarding solar control and storage, is understandable information. Not a load of semantic technical garbage the average person can't and don't want to understand. When you are deeply insecure in your narrow window on life and can see your programming going out the window because it doesn't fit the reality, clones always jump on the band wagon and throw infantile idiocies around like confetti.

[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]

Sounds like an LFP battery around 5-6kWh would do the job and work well with your current equipment. One good thing about LFP batteries is that you can add to them at a later date. This doesn't work well with lead acid batteries.

I agree with you that it is probably a good time to upgrade to a new MPPT controller.

Your temperatures look fairly benign to me, much better than our summertime temperatures. Your mean daily summer temperature would be around 23^oC-25^oC

The big issue with DIY LFP battery systems at the moment is battery management and system integration. I would think you need a battery management system that will make sure that no individual cells go outside their safe operating voltage range and will automatically turn your generator on when the battery SOC gets to say 20%. This may require relays and other bits and pieces that Dax has mentioned in his last post. The complexity of the BMS is dependent on how many of the functions of the BMS you are prepared to do manually, how much risk you are prepared to take, and how much you want to spend. Do you have much knowledge of what is available and what is required?

Simon

I have an understanding of setting up a bms from reading n here, I am warming to lfp so am studying requirements a bit more. Still have a bit of time. I don't have a problem with relays and electrics, so am happy that I can set up a system.

[Sunking]

we stick with 12v, as they are the cheapest components compared to 24-48v and do the job.

This statement here proves you are an idiot with absolutely no understanding what so ever of physics or electricity.Not to mention extremely dangerous asking to burn houses down.

[Sunking]

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,

Spot on Mike. So why do you let this guy on here who knows nothing? For Pete's sake he cannot do simple math and calls himself a designer. He is a FRAUD!

[karrak]

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.

I want my system as simple and reliable as possible.

Sounds like an LFP battery around 5-6kWh would do the job and work well with your current equipment. One good thing about LFP batteries is that you can add to them at a later date. This doesn't work well with lead acid batteries.

I agree with you that it is probably a good time to upgrade to a new MPPT controller.

Your temperatures look fairly benign to me, much better than our summertime temperatures. Your mean daily summer temperature would be around 23^oC-25^oC

The big issue with DIY LFP battery systems at the moment is battery management and system integration. I would think you need a battery management system that will make sure that no individual cells go outside their safe operating voltage range and will automatically turn your generator on when the battery SOC gets to say 20%. This may require relays and other bits and pieces that Dax has mentioned in his last post. The complexity of the BMS is dependent on how many of the functions of the BMS you are prepared to do manually, how much risk you are prepared to take, and how much you want to spend. Do you have much knowledge of what is available and what is required?

Simon

[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.

[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,

[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

[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.

[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]

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.

[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]

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.