LiFePO4 - The future for off-grid battery banks?

[PNjunction]

Simon - can you book us all on some sort of LFP based corporate-retreat? You know, where we practice doing trust-falls, yurts, rope walks, that kind of thing?

I'd bet we'd all do fine in the end.

[karrak]

Why are large capacity LFP cells better?

I just have an issue with a proposed business venture having conflicting interests - starting with the recommendation not to use large-format cells. That was the red flag.

Can you please explain the technical reasons why large-format cells prismatic cells in plastic cases (i.e. Winston, CALB etc) should be better that smaller format cells in metal cases?

Simon

[Living Large]

Can you please explain the technical reasons why large-format cells prismatic cells in plastic cases (i.e. Winston, CALB etc) should be better that smaller format cells in metal cases?

Simon

My recollection is that dax had advised to avoid large format cells. So the issue is not that using large format is better, but that it was cautioned against.

Advantages and disadvantages, assuming both can reliably perform the task, is a totally different topic. Unless you consider can't reliably perform the task a disadvantage, that is.

[dax]

Read the entire thread, and not interested in going over it again, have better things to do. A couple here have claimed lifepo4 doesn't last more than about 3 years, they just listen to the desperate FLA spin. Use proper voltage parameters and lifepo4 perform excellently, with no deterioration in capacity or usable energy.

Using small cell sizes compared to large, simply boils down to economics, system safety, energy safety and longevity of the system. If you had any real experience using and working with large systems, you'd understand. I explained it earlier, but it seems some don't have the experience to understand and are more interested in searching for things they can pick on, rather than understanding the content.

From a money grabbing business point of view, large cells systems are money makers, customer are conned by big claims by makers and we could make much more using them, but our prices would go up a lot, especially if we used USA brands. From a personal point of view, couldn't give a stuff what others use, we take care of our customers and are still doing work for some for the last 30 odd years.

The other companies are also builders, to the best of my knowledge, they don't advertise at all like us, they have more that enough work and like all good business, get their customers from recommendations and word of mouth. If you had any knowledge of the building industry, you'd know most don't advertise in any way and from what I know don't want to become a retail outlets. We asked them if they wanted to work with us a year or so ago, as we are all based in different state markets, but they are happy as they are. Until now, like them, we've never had a web site as there's been no need.

In 40 odd years, we've never advertised our business, but as we decided to expand our market because there is no other outlet for dedicated lifepo4 pack controls and we have found a manufacturer, who can produce and deliver to us much cheaper than we can produce the number we want and they are not in China. We have taken this direction and are setting up a dedicated web site to do that. Again it will be word of mouth that we work on and will be happy to let people know when our web site is up and running, until then we will protect our business plan.

No good bragging we can do something, but are years away from being ready, like telsa. They made a big show and can't support their spin and already losing the market. It has made people curious and looking for alternatives to telsa here. So they did us a big favour by revealing to the public how it can be done and we started getting lots of enquirers from those our customers had shown our systems to.

The great USA telsa bragged about what they can't supply, yet small companies like us have been supplying better systems for years. If you look at the rest of the world you will find the same thing happening, many small business already doing what the bragging big boys claim, but can't provide. Consumer mentality always denies the true reality and that's the case here.

I'm only pointing this all out because there are those in Aus who really want to get into this century and become free of the spiraling energy costs. That's it from me, useless trying to inform those whose head is firmly stuck in consumer mentality, with no business or management experience in any way and have no idea of anything, but the need for an argument and to deny any who show they are badly misinformed. You learn nothing with denial, but denial.

[SunEagle]

Read the entire thread, and not interested in going over it again, have better things to do. A couple here have claimed lifepo4 doesn't last more than about 3 years, they just listen to the desperate FLA spin. Use proper voltage parameters and lifepo4 perform excellently, with no deterioration in capacity or usable energy.

Using small cell sizes compared to large, simply boils down to economics, system safety, energy safety and longevity of the system. If you had any real experience using and working with large systems, you'd understand. I explained it earlier, but it seems some don't have the experience to understand and are more interested in searching for things they can pick on, rather than understanding the content.

From a money grabbing business point of view, large cells systems are money makers, customer are conned by big claims by makers and we could make much more using them, but our prices would go up a lot, especially if we used USA brands. From a personal point of view, couldn't give a stuff what others use, we take care of our customers and are still doing work for some for the last 30 odd years.

The other companies are also builders, to the best of my knowledge, they don't advertise at all like us, they have more that enough work and like all good business, get their customers from recommendations and word of mouth. If you had any knowledge of the building industry, you'd know most don't advertise in any way and from what I know don't want to become a retail outlets. We asked them if they wanted to work with us a year or so ago, as we are all based in different state markets, but they are happy as they are. Until now, like them, we've never had a web site as there's been no need.

In 40 odd years, we've never advertised our business, but as we decided to expand our market because there is no other outlet for dedicated lifepo4 pack controls and we have found a manufacturer, who can produce and deliver to us much cheaper than we can produce the number we want and they are not in China. We have taken this direction and are setting up a dedicated web site to do that. Again it will be word of mouth that we work on and will be happy to let people know when our web site is up and running, until then we will protect our business plan.

No good bragging we can do something, but are years away from being ready, like telsa. They made a big show and can't support their spin and already losing the market. It has made people curious and looking for alternatives to telsa here. So they did us a big favour by revealing to the public how it can be done and we started getting lots of enquirers from those our customers had shown our systems to.

The great USA telsa bragged about what they can't supply, yet small companies like us have been supplying better systems for years. If you look at the rest of the world you will find the same thing happening, many small business already doing what the bragging big boys claim, but can't provide. Consumer mentality always denies the true reality and that's the case here.

I'm only pointing this all out because there are those in Aus who really want to get into this century and become free of the spiraling energy costs. That's it from me, useless trying to inform those whose head is firmly stuck in consumer mentality, with no business or management experience in any way and have no idea of anything, but the need for an argument and to deny any who show they are badly misinformed. You learn nothing with denial, but denial.

Dax

I appreciate you sharing some of your knowledge and data concerning your battery. I am happy your business is taking off and it sounds like the LiFePo4 technology is finally maturing into a worth while energy storage system.

What I do not appreciate is your demeaning manor. Talking down to someone that is trying to understand what you are doing does not help them understand or win you support. What you are doing is the same as those that you are complaining about that have belittled LiFe batteries. Neither form of communication is professional or acceptable.

So I ask that you please continue to access this Forum and provide any help that you can on this technology without revealing any business secrets. Thank you.

[solar pete]

Dax

I appreciate you sharing some of your knowledge and data concerning your battery. I am happy your business is taking off and it sounds like the LiFePo4 technology is finally maturing into a worth while energy storage system.

What I do not appreciate is your demeaning manor. Talking down to someone that is trying to understand what you are doing does not help them understand or win you support. What you are doing is the same as those that you are complaining about that have belittled LiFe batteries. Neither form of communication is professional or acceptable.

So I ask that you please continue to access this Forum and provide any help that you can on this technology without revealing any business secrets. Thank you.

Well said SunEagle, Dax you sound like some spoiled brat to me, if you dont like this place leave no one will miss you.

[PNjunction]

Can you please explain the technical reasons why large-format cells prismatic cells in plastic cases (i.e. Winston, CALB etc) should be better that smaller format cells in metal cases?

Happy to!

The number 1 reason is that small-format cylindrical cells have far more performance than we need in our relatively low-current application. That is, why pay for cells with a capability of 10C charge / discharge when you won't actually do that with a properly sized bank for capacity and autonomy? EV's certainly. Us, no.

Overall complexity - so far I have only been discussing the DIY aspect, and not commercial usage. Never planned to, but we always seem to go beyond the readers of this thread and concern ourselves with the guy next door - who isn't a participant! Large format prismatics cut down the complexity of your wiring infrastructure.

Using large format prismatics are also not behind a walled-garden inside a box you can't see like with small cylindricals. Thus you can't verify the quality of the wiring, nor does it make it easy to spot a cell which may have a problem, but is easily electrically hidden amongst the mass of others.

Small cylindricals make prime targets for grey-market, counterfeit, factory rejects, laptop-pulls, new old stock, constantly changing lowest-bidders and the like. Remember the recent Nissan-Leaf crash cell drama? Yes, stuff works, but some like to just overcomplicate the whole thing. At some point, over-complication becomes a performance and safety issue unless you are a certified commercial manufacturer with the warrantee and resources to back it all up.

Take a look at a MasterVolt LFP, and you'll see - and you'll pay too.

It kind of comes full circle to my mantra : since we aren't in an EV like application, why use EV-like cells with all what entails above just an added worry.

Let's put it this way with something closer to home for many:

I consider Enersys (Odyssey for consumers) some of the best performing pure-lead agm's on the planet. Note that I didn't say longest lasting. If I wanted to build a 500ah bank, would I do so with a massive array of 5ah Enersys / Cyclon small cylindricals, even if they are the best small lead-acid small cylindricals on the planet too? No way, and I even KNOW what I'm buying!

[karrak]

The number 1 reason is that small-format cylindrical cells have far more performance than we need in our relatively low-current application. That is, why pay for cells with a capability of 10C charge / discharge when you won't actually do that with a properly sized bank for capacity and autonomy? EV's certainly. Us, no.

Maybe I should have made myself clearer. I and Dax are not talking about small 18650 cylindrical style batteries and certainly not taking about anything else but LiFePO4 based cells. As Dax has said the cells they are using are 40/50Ah LiFePO4 cells.

Simon

[karrak]

Talking down to someone that is trying to understand what you are doing does not help them understand or win you support. What you are doing is the same as those that you are complaining about that have belittled LiFe batteries. Neither form of communication is professional or acceptable.

I don't see much evidence of some people trying to understand anything.

Maybe it is hard to remain civil after these sort of comments.

"You still have a problem and did not learn what the mistake was. You over discharged your battery, or you over charged them take your pick. The problem surfaced because you did not monitor the batteries an dvoltages. Cell size and format does not matter. Size only matters if you are a ....... "

and

"Uh oh. Usually this indicates that the Winston was abused, or the infrastucture (high-resistance connections) and so forth, or an initial "sanity check" was never done on the factory balance. Failed "bleeder boards", new-old-stock, shipping damage can be an issue, and the biggest one is this:
...
This is the tactic used by el cheapo battery manufacturers that stuff their cases with whoever is the lowest bidder, and the consumer has no idea what the quality of the cells are inside.

Don't take this personally - seeing that, I would never be interested in your systems and run away as fast as I could. As it stands now, the systems you have are just very large version of cheap cellphone chargers taken to the bigger scale."

Simon

[karrak]

My recollection is that dax had advised to avoid large format cells. So the issue is not that using large format is better, but that it was cautioned against.

Advantages and disadvantages, assuming both can reliably perform the task, is a totally different topic. Unless you consider can't reliably perform the task a disadvantage, that is.

If I read it correctly, PNJunction has stated that "we" should only use Large format Prismatics for off-grid system. I want to know on what basis he gives this advice.

Simon

[SunEagle]

I don't see much evidence of some people trying to understand anything.

Maybe it is hard to remain civil after these sort of comments.

"You still have a problem and did not learn what the mistake was. You over discharged your battery, or you over charged them take your pick. The problem surfaced because you did not monitor the batteries an dvoltages. Cell size and format does not matter. Size only matters if you are a ....... "

and

"Uh oh. Usually this indicates that the Winston was abused, or the infrastucture (high-resistance connections) and so forth, or an initial "sanity check" was never done on the factory balance. Failed "bleeder boards", new-old-stock, shipping damage can be an issue, and the biggest one is this:
...
This is the tactic used by el cheapo battery manufacturers that stuff their cases with whoever is the lowest bidder, and the consumer has no idea what the quality of the cells are inside.

Don't take this personally - seeing that, I would never be interested in your systems and run away as fast as I could. As it stands now, the systems you have are just very large version of cheap cellphone chargers taken to the bigger scale."

Simon

Well part of learning to live and post on an open forum like this (and others) is to grow a thick skin and not let what some people say bother you.

So while you may have been offended by those responses they do not reflect everyone's feelings.

I am looking forward to understanding how the LiFePO4 technology has evolved and I feel you and Dax have something to contribute to this forum. I do not want either of you to provide anything that can hurt your business but as an engineer I like to understand what is being said so I yearn for details.

What you want to share is up to you. Just know that while some of us may disagree on what the top battery chemistry is that doesn't mean all of us don't want to understand LiFePO4 technology.

[lkruper]

I don't see much evidence of some people trying to understand anything.

Maybe it is hard to remain civil after these sort of comments.

"You still have a problem and did not learn what the mistake was. You over discharged your battery, or you over charged them take your pick. The problem surfaced because you did not monitor the batteries an dvoltages. Cell size and format does not matter. Size only matters if you are a ....... "

and

"Uh oh. Usually this indicates that the Winston was abused, or the infrastucture (high-resistance connections) and so forth, or an initial "sanity check" was never done on the factory balance. Failed "bleeder boards", new-old-stock, shipping damage can be an issue, and the biggest one is this:
...
This is the tactic used by el cheapo battery manufacturers that stuff their cases with whoever is the lowest bidder, and the consumer has no idea what the quality of the cells are inside.

Don't take this personally - seeing that, I would never be interested in your systems and run away as fast as I could. As it stands now, the systems you have are just very large version of cheap cellphone chargers taken to the bigger scale."

Simon

Simon, I have been wanting to learn and asked questions nicely that were not answered. Might I ask where you have proven that the statements above are not true?

Tis not, Taint So! doesn't really prove anything.

[Willy T]

There are so many different, Manufacturers, Types of cells, Chemistries, Charge / Discharge schemes, Voltages, SOC's, DOD's and Temperature variations to ever come to any conclusion on what lifespan outcome anyone could expect from a given LiFepo4 cell / battery. All these opinions are dizzying to read. Some have them, some don't and some never will and it's all speculation based on nothing or backed up with worthless data based on nothing but a assumption. The difference between individual cells ( cylindrical or flat pouch ) and prismatic batteries where you can have it stuffed with 100's envelope cells is as different as Mars and Earth, trying to extrapolate between the two is useless.

If someones battery last's a month and someones last's 10 years it really proves nothing, except the average is 5 years. Simon has posted the cumulative I/O data of his system. While it seems simplistic, it cuts to the chase, if you want to know more, ask him.

Below is about what you can expect from all the variables of managing LFP batteries ( and not using the correct charging voltages & temperatures as DAX, PNJ and others have posted ), really not all that much different from FLA at 3 time's the cost. If you can live at less than your design capacity, then they may work for you for some time. Everybody thinks they can do a better job with their batteries than the other guy, including me at times.

( From the Bus Guy at technomadia )

So how well have our batteries aged?

When our 500AH batteries were a year old (August 2012), I was able to drain 442Ah from them before having the EMS trigger a low-battery alarm cutoff.

When they were nearing 2.5 years old (November 2013) I was able to drain 409Ah before the system shut down.

Last month (December 2014), during my most recent drain test, I was only able to drain 378Ah before cutting out.

In other words – our batteries seem to be aging way faster than they should – now giving us just 75% of their original rated capacity.

Why? What could be going wrong?

[Living Large]

If I read it correctly, PNJunction has stated that "we" should only use Large format Prismatics for off-grid system. I want to know on what basis he gives this advice.

Simon

Considering PN answered your question an hour before you posted this, there is no need to reply. He stated several advantages to using large format. I still don't recall him saying only large format should be used - but honestly, I don't see why it matters and I'm not paging through comments to hyper-analyze what each person said. This has gotten quite absurd.

[PNjunction]

Time for an apology and a clean slate!

Maybe I should have made myself clearer. I and Dax are not talking about small 18650 cylindrical style batteries and certainly not taking about anything else but LiFePO4 based cells. As Dax has said the cells they are using are 40/50Ah LiFePO4 cells.

Somehow I missed that, so I'll kick the whole thing off with a clean slate as it is getting out of control even for us with thicker-skin.

Dax - I apologize. This whole thing has obviously created some gray hairs, and nobody needs that. I owe you a cold Toohey's or whatever is your beverage of choice.

While cells this size would not be MY preference for a large diy bank, it is do-able.