LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

[john61ct]

Originally Posted by newhaul

So now your advocating for a lead reserve / starter

I was not "advocating" for anything there, just clarifying my thinking in that particular exchange.

When outlining an abstract design concept, simplifying the other elements to highlight the essential point allows for shorter, clearer examples.

Again, and again. There is no one "correct" design solution for all use cases.

Each owner has preferences and existing elements, that changes the various options appropriate for that use case.

For every general statement, exceptional counter-example circumstances can be provided that "prove the rule"

[CatNewBee]

They are called macros.. You can use the two signal BMS macro or create an own one using the whizzard UI.

I use one signal to stop charging generated when the second inverter (Mastervolt MassSine 2000) generates 220V, fed into AC input 2 of the Quattro using the power boost function to get 7kVA, the signal switches off the charger then because both inverter are fed by the battery.

The charger should work on other sources like mains from shore or generator. So detecting the daisy chain and supressing charging, also setting the power assist to 7A input by the macro automatically has done the trick.

The macros are very versatile.

[evm1024]

Originally Posted by CatNewBee

They are called macros.. You can use the two signal BMS macro or create an own one using the whizzard UI.

I use one signal to stop charging generated when the second inverter (Mastervolt MassSine 2000) generates 220V, fed into AC input 2 of the Quattro using the power boost function to get 7kVA, the signal switches off the charger then because both inverter are fed by the battery.

The charger should work on other sources like mains from shore or generator. So detecting the daisy chain and supressing charging, also setting the power assist to 7A input by the macro automatically has done the trick.

The macros are very versatile.

Is there a design doc for implementing these macros? I may have seen it in my explorations of Victron's site but let it slip my mind.

The list of existing (supported?) assistants is here for those who have not found it.

https://www.victronenergy.com/live/a...ble_assistants

[evm1024]

Originally Posted by john61ct

I was not "advocating" for anything there, just clarifying my thinking in that particular exchange.

When outlining an abstract design concept, simplifying the other elements to highlight the essential point allows for shorter, clearer examples.

Again, and again. There is no one "correct" design solution for all use cases.

Each owner has preferences and existing elements, that changes the various options appropriate for that use case.

For every general statement, exceptional counter-example circumstances can be provided that "prove the rule"

Ah.

But, for me it is not an abstract design concept. It is very concrete in the sense that I have the Multiplus, LiFePO4 house bank, AGM starter bank, AGM windless bank, BMS and such. The things I do with my systems and the plans I make are not academic excursions (no matter how interesting the excursion is).

Take Dockhead's need for power boost. He has stated that for years and we should know that and take it into consideration. Just one of those concrete facts.

[CatNewBee]

Ihave used the input current limit control, and the charge current limit control (set to zero) based on the aux input for the second inverter communication and a 220V Finder relay to generate the signal, also use the 2 signal BMS control with the REC ABMS.

Also played around with the advanced controls.

[john61ct]

Specific setups should be in their own thread with the reference data consolidated up front.

Each forum has its own "regulars", but 99% of the value is inherent in the thousands of transient users.

[evm1024]

Originally Posted by john61ct

Specific setups should be in their own thread with the reference data consolidated up front.

Each forum has its own "regulars", but 99% of the value is inherent in the thousands of transient users.

N.B. The myth of the value of thousands of posters should join the list of Common Logical Fallacies.

No Wait. It is on the list - 2) The Bandwagon Fallacy

Thousands of transient users on the internet is just as subject GIGO as they are in any other medium. Not all users postings are of the same value. Simply put a single diamond is worth more than a truckload of gravel.

Thousands of opinions do not make knowledge....

Let me quote from No, you’re not entitled to your opinion

The problem with “I’m entitled to my opinion” is that, all too often, it’s used to shelter beliefs that should have been abandoned. It becomes shorthand for “I can say or think whatever I like” – and by extension, continuing to argue is somehow disrespectful. And this attitude feeds, I suggest, into the false equivalence between experts and non-experts that is an increasingly pernicious feature of our public discourse.

It is a good read - No, you're not entitled to your opinion If that does not take you back to school I don't know what will.

BTW - This thread is a very specific one. It has been greatly useful (a diamond sometimes in the rough) for those of us who are learning and changing our house banks.

[rgleason]

I guess I am still learning a lot from you guys, but I still don't have a good schema for how to wire up a LiFePo main battery bank so that it is protected, properly charges and properly maintained with supply sources from solar, alternator and shore.

You all get into great detail and discussion about things that matter, but the big picture gets obscured. I am sure I could start drawing a system, but would quickly run afoul of some dictum.

This is the sense that other readers get. That is when the eyes glaze over and they move on to some other known and simpler battery technology. It seems to be complicated and they rightfully think the project is likely to head off the rails resulting in a very expensive inadvertent mistake. It is a matter of confidence, and showing the most practical road forward to use LiFePo effectively.

This is a great thread, with loads of experience. It would be wonderful if there were some basics that everyone agreed to, along with some rudimentary diagrams for a reasonable starter system to focus the discussion and develop better ways, good equipment, etc, for doing this.

[john61ct]

Would be nice wouldn't it?

Starting a wiki managed by a group of like-minded users would be a good platform for that.

The medium of a threaded forum doesn't lend itself to arbitrating consensus vs controversy, much less allowing for stable reference notes.

[evm1024]

Originally Posted by john61ct

Would be nice wouldn't it?

Starting a wiki managed by a group of like-minded users would be a good platform for that.

The medium of a threaded forum doesn't lend itself to arbitrating consensus vs controversy, much less allowing for stable reference notes.

This thread is a good platform for those thinking about switching to LiFePO4 and those who have LiFePO4.

It would be nice to spin off a few more threads than we do.

PS No like minded needed. More than one way to use LiFePO4 so we can have very different views.

Higher SNR and such.

[john61ct]

Originally Posted by john61ct

Also, that (finally) sensible

14.2V / 3.55Vpc

setpoint reco from Victron is I think a landmark validation of the "avoid the shoulders" outlook.

Also, their LFP specific version of Cyrix combiner/VSR

> Closes (combines) at 13.7V / 3.43Vpc, opens (isolates) at 13.5V / 3.38Vpc

[senormechanico]

Originally Posted by john61ct

Specific setups should be in their own thread with the reference data consolidated up front.

Each forum has its own "regulars", but 99% of the value is inherent in the thousands of transient users.

Good idea. Let's start with yours.

[rgleason]

Well, it could be done by starting a simple text document or doc, that is iterated and attached in the thread.


This should support different types of uses and may end up as a spreadsheet matrix.

• Power Sources: Solar, Alternator, Shore
• Size: Small 100w-250w, medium 250w-400w, large 400w-800w

I think it should start with completing something like this outline.

• Advantages, problems.
• Goals
• Concept
• System Diagram
• Setpoints & Actions
• Equipment
  • Battery
  • MMS
  • Macro Controls
    • Sensors
    • Relays
• Other equipment
  • Solar
  • Alternator
  • Shorepower
• Integration Solutions

[Dockhead]

Originally Posted by evm1024

N.B. The myth of the value of thousands of posters should join the list of Common Logical Fallacies.

No Wait. It is on the list - 2) The Bandwagon Fallacy

Thousands of transient users on the internet is just as subject GIGO as they are in any other medium. Not all users postings are of the same value. Simply put a single diamond is worth more than a truckload of gravel.

Thousands of opinions do not make knowledge....

Let me quote from No, you’re not entitled to your opinion

The problem with “I’m entitled to my opinion” is that, all too often, it’s used to shelter beliefs that should have been abandoned. It becomes shorthand for “I can say or think whatever I like” – and by extension, continuing to argue is somehow disrespectful. And this attitude feeds, I suggest, into the false equivalence between experts and non-experts that is an increasingly pernicious feature of our public discourse.

It is a good read - No, you're not entitled to your opinion If that does not take you back to school I don't know what will.. . . .

Even better:

"If 'Everyone’s entitled to their opinion' just means no-one has the right to stop people thinking and saying whatever they want, then the statement is true, but fairly trivial. No one can stop you saying that vaccines cause autism, no matter how many times that claim has been disproven.

"But if ‘entitled to an opinion’ means ‘entitled to have your views treated as serious candidates for the truth’ then it’s pretty clearly false. And this too is a distinction that tends to get blurred."

Ibid.

And just so. And that's how it works here. When something is posted which is in error, the idea is discussed and the errors are pointed out. People have equal rights to post, but what is erroneous and what is true comes out in the discussion. POLITE AND RESPECTFUL discussion, I might add. It is entirely possible to treat an expressed view as "not a serious candidate for the truth", without disrespecting the person who posted that view and thus violating the Rules of the forum.

It is always obvious, eventually, who really understands a given subject and who does not. So those who understand a given subject need not fear the erroneous comments of those who do not. On the contrary, that is one of the great advantages of discussion in fora like this, as opposed to sitting in an engineering faculty somewhere and discussing only with "like minded people" with the same background and training and large body of received ideas which are never questioned. Politely arguing with erroneous views is terrifically useful in improving your own thinking and finding your own mistakes, which all of us without exception have.

[CatNewBee]

I agree, but I am not sure how to use the forum software for this, I started my thread about a year ago specifically to my setup (Winston 1000Ah LiFeYPO4 battery and all electric galley) intentionally to show a working project, the thoughts behind the dessign, the circuit diagramms explained in detail, the changes to the original manufacturer wiring, and finally the use pattern and discussions about improvements.

The first 20 posts are really focussed on the details as a type of blog with very little clutter. The discussions afterwards is as always going in all directions, but the initial dessign is compact at the beginning.

You cannot change or append old posts unfortunately, so additions and fixes are done among the clutter somewhere. You need a read only blog to keep the content in context and a free discussion part about the project for all questions, opinions and off topic issues. But as far as I understand the CF plattform, there is no easy way to achive this.

On a general LFP thread like this one you compare various setups and discuss pros and cons.

When you are ready for your install, start a new thread, write down your thoughts in a text document, prepare the pictures of the circuit diagrams, the gear used etc. Then post all the stuff at once or in close sequence before going into the discussion to keep the first posts clean and complete.

I have no other work around at the moment.