Lithium-ion multiple batteries on parallel - same challenge as Lead Acid or not?

[Sunking]

(1) The original poster expressly referenced TESLA systems, which are based upon 18650 lithium ion batteries, thus my correct statement that there is no such thing as a solar charge controller for LI batteries,

Again you are clearly demonstrating you have no clue what you are talking about. There are a number of charge controllers that can be used on any type of lithium battery. I bet your customers would like to know just how clueless you are and a pretending to be a pro.

Here is you a list of charge controllers that can charge any Lithium Ion cell chemistry.

Genasun
Morningstar
Midnite Solar
Victron

There are many more I will not waste my time listing for you. It is obvious to me you have never worked with any of those manufactures. I base that on the fact the Chi-Com POS DC Converter you linked too you find at AutoZone and low end golf cart shops. That is exactly what a Shade Tree mechanic would use because they do not know better.

Any of today's smart battery chargers and solar charge controllers can charge any battery chemistry. It is real simple, they all allow you to program the voltage set points. Now if you use cheap Chi-Com parts from the auto or RV shop, they have fixed output and use a slector switch of Gel, AGM, or FLA. But even those can charge any LFP battery because LFP is compatible with Pb batteries. Now get lost.

[J.P.M.]

(1) The original poster expressly referenced TESLA systems, which are based upon 18650 lithium ion batteries, thus my correct statement that there is no such thing as a solar charge controller for LI batteries, because there isn't any. Learn to read before attacking what I write. (2) The Internet is full of references to "charging strategies" (e.g., Battery University). It is a military analogy is to strategy and tactic: the strategy is the sequence of events to be implimented and the algorithm is the specific tactic that implements the strategy. Learn to speak the English language correctly before attacking my usage. (3) You are correct about the shade tree part in the sense that electronic engineering did not yet exist when I became design verification engineer for architect John Coleur at MIT. I am 80 years old and worked mainly with hardware engineers writing microcode. (4) All of this is just another exercise in semantics by a second guy who probably does no more actual work than the first guy who tried the same stunt. I will ask you the same question: "How long have you been running your home and business entirely off-grid using first lead-acid and now lithium-ion batteries, as I have been for more than six years?"

Some observations:

- To write : "there is no such thing as a solar charge controller for Li batteries, because there isn't any" seem a bit of flawed to me by virtue of the circular logic used.

- The definitions of the words strategy and tactics may or may not be used in a military context. To say they are strictly military terms and restricting them to that realm is probably anachronistic. Not necessarily incorrect usage, but it seems somewhat narrow to restrict usage for those words in that way. What about sales strategy or design strategy - two uses I've seen.

- If, or to the degree one accepts the birth of electronic engineering to be in 1948 when Bardeen, Brattain and Shockley invented the transistor, that would mean you were 10 years old when you became a design verification engineer, probably in MA. I thought child labor laws in MA wouldn't allow that. But, no matter now. I'm surely not surprised that someone with a 95,000 word English vocabulary would be a child prodigy in the field of electronic engineering as you obviously were, but employed ? For wages ?

- Battery University looks like a front for peddlers to me. Claims to be free. Well, so is this site and you get what you pay for or less. Or, maybe it's about as much of a university as what McDonalds calls "Hamburger University" to train burger flippers.

I thought I saw something from you two posts ago where you expressed some displeasure about how the value of this exchange (thread, or subset posts ?) has degraded beyond any value and you said goodbye. When folks post stuff such as that, I've usually found it to mean they're out of here. Change your mind, or find something of value, or both, or am I under a set of bad information, or something else ? Couldn't find words to adequately express your displeasure without resorting to a thesaurus ?

Take what you want of the above. Scrap the rest.

[Sunking]

(1) that there is no such thing as a solar charge controller that uses the correct charging strategy for lithium ion batteries

You call yourself a professional but this statement and your claim there is DC Transformer proves you are not a pro, just a shade tree mechanic at best . LFP batteries are direct replacements with Pb batteries which means any solar charge controller will work. In fact Lithium Ion batteries are the easiest and simplest to charge as they only require a stupid simple CC/CV algorithm. Again your terminology is completely wrong. It is not a Strategy, it is called ALGORITHM, not Strategy.

[Mike90250]

... Functionally, there is no material difference between a buck converter and a reducing transformer.....

Sadly, you are not dealing with John Q. Public. This forum has a large population of engineers, and for engineers, proper nomenclature is critical for communication.

When you first mentioned DC transformer, I asked you about it, and you posted a link to a amazon P.O.S. I have since discounted all communications with you, as being unteachable. I will push back and not allow you to use fake or erroneous terminology and not be called for it.

Other educated people also, will not let you mis-inform people here.

[Sunking]

The difference between us is that I sell daily to real people. I have never even one time had a customer ask me fror a "buck converter".

That is because the public is as ignorant as you are, and as a salesman wil tel the customer what they want to hear like any salesman. Salesman need not apply here, we do not tell folks what they want to hear. No one here is vested in a one solution forum. We give the facts on both sides to educate the public so they can make informed decisions.

Go over to the Arizona and Wind & Sun Forum where all the snake oil salesman go to peddle their goods and tell people what they want to here. Both moderators and regular users here will tear you apart, especially if you do not know what you are talking about or only a one solution pundit. You know a person who calls themselves a professional and does not know the difference between a Converter and Transformer or the terms used. I am not vested in any solution. If lithium is the best fit for an application, that is what I go with like an EV's, power tools, or mobile application where weight and size justifies the expense and risk. For stationary applications, lithium is not a good option, just hype full of false claims and promises by snake oil salesman peddling their goods on the ignorant public.

[Sunking]

How long have you been living and working entirely off-grid?).

Never, I am not that stupid to pay 5 to 10 times more for limited power. Been designing building them for about 15 years, and in power generation for about 40 years. Only thing I have solar powered is my ham radio shack which is all built with manufactures samples they give me because I buy and use so much they give me to try out and work with. Like a drug dealer, I do not care what you do with the product, I just provide a service to make a living. The difference is I give my customers the most bang for the buck, works as expected, and as safe as humanly possible. Using lithium batteries for residential power defeats all those objectives.

[Sunking]

Forgive me because I have only a 95,000 word vocabulary in English; so I'm understandably short-tempered with semantical nonsense.

You are the one spouting semantical nonsense which is understandable, you are a mechanic. Look up the definition of a Transformer.

Transformer: A transformer is a static electrical device that transfers electrical energy between two or more circuits. A varying current in one coil of the transformer produces a varying magnetic flux, which, in turn, induces a varying electromotive force (emf) or voltage across a second coil wound around the same core. Electric power can be transferred between the two coils, without a metallic connection between the two circuits. Faraday's law of induction discovered in 1831 described the induced voltage effect in any secondary coil due to changing magnetic flux cutting it.

Transformers are used to increase or decrease the alternating voltages (AC Power) in electric power applications.

DC cannot pass through a Transformer unless there is a Center Tap on both Primary and Secondary coils called SIMPLEX, but the DC voltage does NOT CHANGE. An example is your telephone line. That is why Mike and Steve busted your chops because they and I know there is no such thing as a DC Transformer. They are DC-DC Converters which are electronic. A transformer is a passive device with nothing electronic inside them.

[Sunking]

Here is the Amazon product title for the transformers that I am now using:

LOL. That is not a Transformer. It is Buck Converter and is made for golf carts to CONVERT a 36 or 48 volt golf cart battery to 12 volts for head/brake lights, stereo, and 12 volt gizmos. They are Chi-Com POS converters and they do not last long.

[Sunking]

Thank you. You confirmed my understanding that the balancing on my Tesla starts somewhere between 80 and 90% of what they show on the screen as 100%. In actuality that 100% is probably only 90% of full capacity. You can call that middle balancing if you like..

You clearly do not understand terminology.

EV manufactures can do what no consumer can possible do. They can match the cells to within 1% because they have hundreds of thousands of cells to work with and DO NOT use LFP cells. All anyone has to do is wire all the cells in PARALLEL and walk away 24 hours and they are MIDDLE BALANCED perfectly. Now if you want to TOP BALANCE, you would then leave them in Parallel and charge them to 4.2 volts until current tapers to 3% of C. If you want to BOTTOM BALANCE you discharge them to 3.0 volts.

TOP BALANCE means every single cell is charged to 100% capacity.

[Mike90250]

....

THIRD, since most people (customers) do not understand DC, and are unwilllng to lean even for efficiency's sake, convert to AC at the earliest physical opportunity. Given the minimal configuration described above, input voltage will range between 37v and 44v (the upper value allows for 10% rise in voltage during cold weather, with corresponding drop in amperage), This input should power a (usually automotive or marine) transformer with an input range about 15v to 50v and a constant output of about 12.2v. That output is perfect for just about every modified or pure sine wave inverter.....

Wow. a DC transformer with 15-50v input and 12.2v output. care to share any sources or specs for these wonderful creatures ?
( I added the bold font to your quoted post )

[sdold]

These transformers you speak of certainly accomplish more than any transformer I've ever seen. Please give an example make and model of such a device.

[Ampster]

.......No all commercial EV's Middle Balance. ......
..... Near the TOP is Not TOP BALANCE, it is Middle Balance. ........

Thank you. You confirmed my understanding that the balancing on my Tesla starts somewhere between 80 and 90% of what they show on the screen as 100%. In actuality that 100% is probably only 90% of full capacity. You can call that middle balancing if you like. I think it is more clear to say it is near the top. To me the middle is closer to 50% but that difference may be semantics and not worth disagreeing over.

This entire discussion also gives me confidence that I will get several hundred thousand miles on that pack.

[Sunking]

My question was related to an EV not a consumer BMS. I have always thought the BMSs on my EVs ran the balancing currents near the top of the charge curve. Therefore I assumed they were top balancing. Is that not the case?

No all commercial EV's Middle Balance. No EV manufacture would allow the consumer to ever fully charge the battery. If they did, they would go bankrupt with warranty claims. Depending on the EV auto manufacture, they only allow the battery to be charged up to 80 to 90% capacity, and only discharge to 10 to 20% capacity.

EV manufactures do not use Balance Vampire Boards. Only consumer grade BMS use Balance boards. Near the TOP is Not TOP BALANCE, it is Middle Balance. For me on every EV, Golf Cart, and Solar System, I DO NOT USE ANY BMS. Custom EV Conversion companies learned a long time ago the BMS is the number 1 killer of Lithium batteries. We mimic what commercial EV manufactures do by using Bottom Balance, and only charging to 90 to 95% capacity, and cut-off at 10%. This doubles to quadruples cycle life and eliminates the possibility of over discharging a battery. If you Top Balance sets you up for the perfect storm of over discharged cells. Super easy to do and requires no add-on equipment like an expensive BMS or special charger.

[Ampster]

..... A consumer grade BMS cannot balance an unbalaced battery pack. ....

My question was related to an EV not a consumer BMS. I have always thought the BMSs on my EVs ran the balancing currents near the top of the charge curve. Therefore I assumed they were top balancing. Is that not the case?

[Sunking]

When you say top balance do you mean when the BMS shunts start working or are you talking about putting all cells in parallel and charging that group to something close to max voltage?

It is the same thing. A consumer grade BMS cannot balance an unbalaced battery pack. It can take weeks or months to do that if you tried and would destroy the weaker cells.