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

[evm1024]

I don't think you addressed my central premise. Let me state it again for your consideration.

Originally Posted by evm1024

I think it is fair to say that the majority if not all cruisers are NOT interested in getting the theoretical maximum longevity out of their LiFePO4 house banks. (or LA bank for that matter) In short, cruisers Do have an interest in those "care free" kind of usage patterns. The discussion of getting a theoretical maximum lifetime for a house bank, which may be enjoyable to some, yet is so removed from reality, or experience that it has no practical use.

Simply put: Cruising is a maintenance intensive activity and the more "care free" my house bank is the better.

N.B Care free does not imply that there is not a very capable technology "underneath the hood". Or that the user is ignorant. Case in point - Finding your position with a GPS is very care free compared to finding your position with a sextant.

Also,

It's all grey-scale judgement calls.

Taking a slop-jar attitude to even the critical risk factors is all fine and good, but I'm pretty sure those owners won't be using the same bank in twenty years.

First off no boat owner that I know of has ever gotten 20 years out of their house bank. That is not to say that it does not happen. No I take that back, One boat in our marina got 20 years out of a set of 2 volt 1000 AH Rolls 24 volt bank that he rarely discharged below 80% SOC. And owns a boat building business.

Of course it is all a spectrum of design/usage trade-offs. I don't see how grey-scale judgement calls is compatible with the very black and white I have no interest in those "care free" kind of usage patterns.

I noticed that you use terms like Taking a slop-jar attitude and not out of ignorance. I hope you are not calling my postings slop-jar or ignorant.


BTW, Wrong Eliza.

[newhaul]

Originally Posted by john61ct

I don't think there **is** a "theoretical" maximum for cycle life, unless I suppose where calendar aging becomes the more significant factor.

.
.

actually as I am to understand it calendar / shelf aging is only relevant prior to initial use.
Ymmv

[Q Xopa]

Originally Posted by john61ct

Which Eliza, Pertigkiozoglou?

Of course I mean actual usage.

For example, disconnecting the bank from Floating charge sources while they continue to carry ongoing loads.

Given today's mainstream systems currently on the market, many here say "impractical" or " too hard!" In reality it is easy to do if you want to, especially with a setup where only the main protective BMS-functionality is automated.

If full "carefree" automation is desired, then a higher level of tech literacy is required to implement that goal and also retain a high level of secure reliability.

Charging to a lower than maximum setpoint, or ensuring a higher than minimum LVC are **very** easy to implement, require no special skills.

Similarly avoiding charging when batteries get below freezing.

What if someone in a cold climate were to say, gee that seems hard, I'll just take my chances?

Few BMS offer such protection, yet I would not personally consider it optional.

There isn't a sharp B&W line duality here between "I want longevity" and ¯\_(ツ)_/¯

It's all grey-scale judgement calls.

Taking a slop-jar attitude to even the critical risk factors is all fine and good, but I'm pretty sure those owners won't be using the same bank in twenty years.

I guess this all comes down to how we choose to prioritise our time. Some of us spend our time fixing our boats and cruising. Others like to theorise and spend their time writing posts about their theories on forums.
'What ever floats your boat' I suppose.

[CatNewBee]

Originally Posted by evm1024

...
BTW, Wrong Eliza.

Let me guess,

"Hi, I am Eliza, tell me your problem..."

Sinclair ZX81 in basic written KI program from the 80's, that mainly takes the answer and creates a new question out of it or just repeats a set of general questions to keep the dialogue running?

Original from Weizenbaum developed in the 60's at the MIT https://en.m.wikipedia.org/wiki/ELIZA

[Dockhead]

Originally Posted by evm1024

I think it is fair to say that the majority if not all cruisers are NOT interested in getting the theoretical maximum longevity out of their LiFePO4 house banks. (or LA bank for that matter) In short, cruisers Do have an interest in those "care free" kind of usage patterns. The discussion of getting a theoretical maximum lifetime for a house bank, which may be enjoyable to some, yet is so removed from reality, or experience that it has no practical use.

Simply put: Cruising is a maintenance intensive activity and the more "care free" my house bank is the better.

In my case I am after an acceptable cost house bank that has an acceptable life span that requires as little as reasonable of my time to keep healthy and just plain works.

If I were to choose between a care free bank that lasts 5 years or a bank that requires significant time to keep healthy and lasts 8 years you can guess my answer.

I'll take the 5 year bank any time. Oh, wait - I've got 5 years on my LiFePO4 bank already. Even with B grade cells I am happy with the banks performance lost capacity or not. Chasing theory is basically a waste of my time.

That of course is just my opinion.

I'm still just lurking on here, absorbing information to help with my own installation which I hope to accomplish over the winter.


But I thought I'd jump in here to say that I have found it surprising that people seem to so rarely think in a holistic way about their performance standards, particularly with regard to service life of the battery bank.


You can't design anything without knowing what you want the system to do. I realized early on that chasing the ragged edge of maximum possible cycle life was not going to be a design value for my particular use case.



Batteries living more than 15 years is just not a priority for me. I won't have this boat, or probably not even the next boat, for that long. Technology will have moved on in 15 years, I'm quite sure. I don't cycle my batteries more than 100, maximum 150 times a year. So a couple thousand cycles is more than enough for me.


On the other side, eliminating all this worry about PSOC is immensely valuable. Reducing generator run times. Never worrying again about what state of charge you leave the batteries in. Never worrying because you have to leave the boat without shore power on. And increased performance of high current devices. All this is extremely valuable to me, and most of all the greater simplicity in operation of a lithium system which is properly designed and set up.


All that is worth the time and thought to design one of these systems, for me, anyway (and the process itself is fun and interesting), and the investment in different infrastructure.



But the difference in cycle life between 2000 cycles and 3000 or 5000 cycles? Completely meaningless to me, and I suspect, to 99% of us also.



Even more so when you consider that the cost of the cells is actually quite modest, roughly the same where I live as quality lead batteries, per amp/hour of actual usable capacity. People seem to think of the cost of a lithium battery in terms of the total cost of installation with all of the infrastructure. But that's not right -- we don't consider the cost of a lead bank to include the cabling, special four stage charger necessary for lead, special alternator regular necessary for lead. Because you reuse all that stuff whenever you have to change the batteries themselves.


The cost of the cells is such that even if I had to change the cells in 7 or 8 years, it wouldn't be any kind of tragedy, and that's assuming the cost will be the same in 7 or 8 years, which I don't think it will. That would be a similar operating cost to using quality lead batteries, but along the way you would have had vastly less worry and messing about, than you would have with lead.



I'm just saying that I don't think that one should fail to formulate performance standards, and keep them in mind, when thinking about these systems. Simplicity in operation is an extremely important design value for my particular use case, and I suspect for others as well, and I think it is in an inherent advantage of lithium.

[CatNewBee]

@Dockhead:

Soo true. Batteries are consumables.
My battery is 1.8 years old now, provided 75600Ah, so 75 full discharge and charge cycles, been in total about 8 monts living on board and using it excessively for heating, cooking, charging tools, sailing, whatever.

Victron monitor counts only 31 cycles and 46 synchronizations, battery was online during the winter kept up by reduced solar settings.

Provided over 1000kWh so far.

We are now full time cruisers. Battery is maintenance free. With the old FLA setup (4x120Ah GEL) it would not be possible to live off-grid and at anchor, making daily water, cooking, sailing for weeks without the need to go on shore for supplies thanks to the fridges and freezers. Our average use is about 50% of the capacity (550Ah), we would need a very large FLA bank if even possible to do it with FLA.

It's just the quality of life you get when you not need constantly to care about energy or high current applications. With FLA there is a significant voltage drop when using winches, windlass or the inverter, with LFP there is almost nil. Being able to draw constantly over 500A is a huge benefit. It is only 0.5C, in theory continous draw of 1000A are feasible, and for short time up to 3000A. Charging is another benefit, the battery absorbs everything until full in contrast to the shallow FLA curve.

I am sure, it will last for the time we intent to sail. And if not, I would replace it with the same setup. Not needing the generator is a huge benefit, and if needing it, being able to recharge from empty to full in 2 hours is priceless.

[Q Xopa]

Originally Posted by Dockhead

I'm still just lurking on here, absorbing information to help with my own installation which I hope to accomplish over the winter.


But I thought I'd jump in here to say that I have found it surprising that people seem to so rarely think in a holistic way about their performance standards, particularly with regard to service life of the battery bank.


You can't design anything without knowing what you want the system to do. I realized early on that chasing the ragged edge of maximum possible cycle life was not going to be a design value for my particular use case.



Batteries living more than 15 years is just not a priority for me. I won't have this boat, or probably not even the next boat, for that long. Technology will have moved on in 15 years, I'm quite sure. I don't cycle my batteries more than 100, maximum 150 times a year. So a couple thousand cycles is more than enough for me.


On the other side, eliminating all this worry about PSOC is immensely valuable. Reducing generator run times. Never worrying again about what state of charge you leave the batteries in. Never worrying because you have to leave the boat without shore power on. And increased performance of high current devices. All this is extremely valuable to me, and most of all the greater simplicity in operation of a lithium system which is properly designed and set up.


All that is worth the time and thought to design one of these systems, for me, anyway (and the process itself is fun and interesting), and the investment in different infrastructure.



But the difference in cycle life between 2000 cycles and 3000 or 5000 cycles? Completely meaningless to me, and I suspect, to 99% of us also.



Even more so when you consider that the cost of the cells is actually quite modest, roughly the same where I live as quality lead batteries, per amp/hour of actual usable capacity. People seem to think of the cost of a lithium battery in terms of the total cost of installation with all of the infrastructure. But that's not right -- we don't consider the cost of a lead bank to include the cabling, special four stage charger necessary for lead, special alternator regular necessary for lead. Because you reuse all that stuff whenever you have to change the batteries themselves.


The cost of the cells is such that even if I had to change the cells in 7 or 8 years, it wouldn't be any kind of tragedy, and that's assuming the cost will be the same in 7 or 8 years, which I don't think it will. That would be a similar operating cost to using quality lead batteries, but along the way you would have had vastly less worry and messing about, than you would have with lead.



I'm just saying that I don't think that one should fail to formulate performance standards, and keep them in mind, when thinking about these systems. Simplicity in operation is an extremely important design value for my particular use case, and I suspect for others as well, and I think it is in an inherent advantage of lithium.

You can count me as one of your 99%.

At the risk of being too agreeable and forum boring, your version sounds pretty much my how I see it. Lack of PSOC issues, charge efficiency and speed are reason enough, IMO, to be worth spending a bit of cash and time to learn upfront.

Spending so much time chasing the last gasp of life outta batteries, sails, engines, anything is to me a waste of potential sailing and living life time.

[evm1024]

Originally Posted by CatNewBee

Let me guess,

"Hi, I am Eliza, tell me your problem..."

Sinclair ZX81 in basic written KI program from the 80's, that mainly takes the answer and creates a new question out of it or just repeats a set of general questions to keep the dialogue running?

Original from Weizenbaum developed in the 60's at the MIT https://en.m.wikipedia.org/wiki/ELIZA

My first intro to Eliza was on a CDC 6600 that was upgraded to a Cyber 73 if I remember right.

Dang, I'm still playing with computers.

[senormechanico]

When evaluating the cost per aH benefits of lithium, don't forget to remember the savings in not having to buy new t shirts and pants because of all the holes made by the lead acid batteries !

[Delfin]

Originally Posted by Q Xopa

You can count me as one of your 99%.

At the risk of being too agreeable and forum boring, your version sounds pretty much my how I see it. Lack of PSOC issues, charge efficiency and speed are reason enough, IMO, to be worth spending a bit of cash and time to learn upfront.

Spending so much time chasing the last gasp of life outta batteries, sails, engines, anything is to me a waste of potential sailing and living life time.

Ditto that. Also, I did an analysis of the cost of running the genset for the additional time it takes to charge LA batteries, and depending on the size of the genset and the days per year cruising, you can pay for the difference between LFP and LA in fuel and maintenance cost reductions.

[newhaul]

I have reworked my power usage and if I change to 1s4p3p for 300ah I can install a 2kw inverter to run my electric galley appliances . I will be using calb cells purchased from the factory. With a 200amp bms

With 400 watts solar and 400 watts wind I figure I may as well get the most out of it .
Besides I really like my instapot at home want it on the boat .

[Steve_C]

Originally Posted by newhaul

I have reworked my power usage and if I change to 1s4p3p for 300ah I can install a 2kw inverter to run my electric galley appliances . I will be using calb cells purchased from the factory. With a 200amp bms

With 400 watts solar and 400 watts wind I figure I may as well get the most out of it .
Besides I really like my instapot at home want it on the boat .

Ok I am a little slow this morning How do you do 1s4p3p ??????

[CatNewBee]

Originally Posted by Steve_C

Ok I am a little slow this morning How do you do 1s4p3p ??????

I guess it will be 1 string of 4 packs containing each 3x 100Ah Cells in parallel to make a 12V 300Ah bank?

Very confusing indeed.
Anything else makes no sense to me.

[Steve_C]

Originally Posted by CatNewBee

I guess it will be 1 string of 4 packs containing each 3x 100Ah Cells in parallel to make a 12V 300Ah bank?

Very confusing indeed.
Anything else makes no sense to me.

I thought that would be 3p4s ?

3 cells in Parallel and then in a series of 4 ?

[newhaul]

Originally Posted by Steve_C

I thought that would be 3p4s ?

3 cells in Parallel and then in a series of 4 ?

unless its 3 separate 1p4s 100ah then 3s for 300ah total . 3 separate 12 volt batteries .