What size LiFEPO4 bank

[ramblinrod]

Originally Posted by newhaul

A few things.
1 ) there is infinately more maintance required with fla banks.

2) when amounrorized over the full lifetime lfp batteries are wh for wh considerably cheaper.

3) the price of lead based batteries is fairly static . However the price of lfp batteries is declining rather rapidly as the chemistry becomes more mainstream.

Lastly there is no real difference wrt charging the batteries whether it be fla or lfp they both require simmilar charge voltages lfp just charges much faster.

And regarding your last sentence, if one charges mostly by renewable energy sources, on a good day, the batteries will be fully charged, regardless of chemistry.

With the cheapest FLA, if sized properly, most days they won’t get below 75%, and will be back to 100% with renewable charge sources well before sundown.

In the event of low solar consecutive days, if the FLA gets down to 50% when one wakes up in the morning, they fire up the ICE charger for an hour to bring them up to 75% at a rate of about .25C, and then let’s the renewable charge sources do the rest.

Conversely, if one had LFP and they had the same capacity, they may be able to go another day, but if they reduced capacity as many claim they can, they too would be ICE charging and if trying to get the max life cycles everyone touts about, then they will charge at around .3C, and in about 50 minutes, shut down to let renewables do the rest.

Spend all the time, effort, and money, to save 10 minutes of ICE running time, maybe once, possibly twice per week, is simply not worth it to me, and when I’ve explained these truths to others, then they really don’t understand what all the LFP hype is about.

If one has deep pockets and a stinkpot with a big generator and no desire to get solar and or wind, I get it; and if one has deep pockets and a high performance,weight sensitive blow boat (e.g. Ocean Race competitors), I also get it.

For average folks that are trying to preserve the cruising kitty, there’s not much better game in town than proper quantities of cheap FLA, renewable charge sources, and cheap ICE alternator for a little boost on cloudy, windless days.

[newhaul]

Originally Posted by ramblinrod

Oh really, top up FLA water level once or twice per year, 10 minutes per battery tops. Vs constantly monitoring LFP so you don’t over ornunder charge and wreck them completely. ]

You forgot about cleaning all of the connections that have developed corrosion due to exposure to sulpheric acid fumes.

Lfp you have yo do nothing .

[Unless the LFP get damaged due to fault and one has to replace the bank in the first month or so, or if one sells the boat before 10 years or so and don’t get the benefit of longer life. (It is actually more likely the next owner will realize the financial gain when he buys the ~ 5 year old batteries at pennies on the dollar. ]

if you as the service provider properly install and setup the bank that will not happen.

[3)

Which including the initial and annual depreciation plus reduced price of new is why one will realize only pennies on the dollar. ]

over the life of Lfp the cost is half that of Fla watt hour for watt hour is a proven and posted in several threads on here.



[Yeah right, until a HVD shuts the bank down and the alternator diodes blow, and leaves the boat stranded with no house bank power until the LFP batteries comes back on line, if they weren’t damaged by the FLA compatible absorption stage that can be held almost indefinitely by some chargers if the house load won’t let the charger go to float.]

see above if properly setup to begin with this doesn't happen.


[I’m not against LFP, just tired of hearing (a term derogatory of others has been removed by moderator) glossing over the very important details which mean they may not be right for everyone.]

that derogatory term doesn't bother me I'm a consmate professional in everything I do.

it is proven that you have a bias towards Fla . And that's ok I have done lots of Fla I stalls and maintain them as well however when a poster is asking for specifically Lfp advice that is what I will give him.


[If any individual wishes to buy LFP after learning all pros and cons I could care less, but be aware, there are cons, there is to every boat decision one can make.

I have been running my own Lfp bank for 2.5 years the only time I even look at them is when I do an annual capacity test . ( still putting out 118ah out of a 100ah bank)

[newhaul]

Originally Posted by ramblinrod

And regarding your last sentence, if one charges mostly by renewable energy sources, on a good day, the batteries will be fully charged, regardless of chemistry.

With the cheapest FLA, if sized properly, most days they won’t get below 75%, and will be back to 100% with renewable charge sources well before sundown.

In the event of low solar consecutive days, if the FLA gets down to 50% when one wakes up in the morning, they fire up the ICE charger for an hour to bring them up to 75% at a rate of about .25C, and then let’s the renewable charge sources do the rest.

Conversely, if one had LFP and they had the same capacity, they may be able to go another day, but if they reduced capacity as many claim they can, they too would be ICE charging and if trying to get the max life cycles everyone touts about, then they will charge at around .3C, and in about 50 minutes, shut down to let renewables do the rest.

Spend all the time, effort, and money, to save 10 minutes of ICE running time, maybe once, possibly twice per week, is simply not worth it to me, and when I’ve explained these truths to others, then they really don’t understand what all the LFP hype is about.

If one has deep pockets and a stinkpot with a big generator and no desire to get solar and or wind, I get it; and if one has deep pockets and a high performance,weight sensitive blow boat (e.g. Ocean Race competitors), I also get it.

For average folks that are trying to preserve the cruising kitty, there’s not much better game in town than proper quantities of cheap FLA, renewable charge sources, and cheap ICE alternator for a little boost on cloudy, windless days.

lets see I have a 100ah Lfp bank . I have been charging solely on solar for 2.5 years .
My bank is up to my chargers cutoff voltage of 13.8v usually by 10 am rarely still charging past 1300 . That is when I start my watermaker to use the excess power that the panels are making otherwise it is wasted . If I don't need water or after the tank is topped up I run my rice cooker (300 watt) for the 20 minutes it takes to make the 3 cups dry to cooked rice.

If I use more than I make the rest of the day will top them.

In the event of low solar days I still get charged. As needed but in the event of bad for or heavy rain and no solar I can run off of the bank for 3 days easily before I need to think about converging power.

That many days will take the battery down to 25% . And due to acceptance rate I can put all 400 watts into the battery till full .
A consistent usage pattern like this won't affect Lfp but Fla will die a premature death due to PSOC.

Deep pockets are not needed with Lfp anymore. I can get good quality 240ah Lfp 12v bank and the bms for it for under $550.

For the same 240 ah Fla 200ah usable capacity . It will cost about $500 due to needing 400ah total capacity . To maintain an average of not going below 50% capacity .
Several days with low charging g will require either putting into port for shorepower charging or several hours running the ice. .

When you add all the parts of it into the formula Fla is considerably more expensive over a 5 year life on the hook / not on shorepower.

Then you need to replace the Fla due to it being killed by PSOC .

That being said I actually recommended that one of my customers with s 50ft trawler that he only needed 220ah of Fla due to him being a marina hopper when crabbing in his grounds.

[john61ct]

Originally Posted by ramblinrod

I call, “BS.”

Why would that make you skeptical?

Not everyone cares enough to strive for optimal longevity, in fact likely only a tiny percentage.

Most owners get away with ignoring their bank for years, and in fact their primary goal is to be care free,

they're happy if it lasts well under a decade.

And some people are just lucky too.

[ramblinrod]

Originally Posted by john61ct

Why would that make you skeptical?

Not everyone cares enough to strive for optimal longevity, in fact likely only a tiny percentage.

Most owners get away with ignoring their bank for years, and in fact their primary goal is to be care free,

they're happy if it lasts well under a decade.

And some people are just lucky too.

I’m sorry, but I don’t believe this for minute.

I suspect that if one valued their time at just minimum wage, for the research, product spec, sourcing, purchasing, receiving, inspecting, familiarizing, assembling, installing, configuring, testing, there’s likely another $2000 or more to add, and then the shipping, customs brokerage, cable mod, battery box mod, hardware. When all is said and done, I bet that 100 Ahr LFP battery had a real cost of $2500 to $3000.

Remember I do this kinda stuff for customers all the time, for years and years and years. Of course my time is worth lots more, but I can do it much faster just due to same stuff different day, been here, done that, many, many, many times.

This is what some folks don’t get about DIY, they’re trading their time for money (hired labour savings). We can always make more money...

For those who prefer to work on their boats instead of sail them, no problem, but it doesn’t change the real cost. They could just as easily be using that time to generate additional income.

[john61ct]

We all see reality through the lenses of our own personal value systems.

Some greatly prefer spending time on "leisure" activities that others abhor, over whatever they've chosen to earn money.

In the end, economic calculations are just one dimension of life, and a very shallow one.

[newhaul]

Originally Posted by ramblinrod

I’m sorry, but I don’t believe this for minute.

I suspect that if one valued their time at just minimum wage, for the research, product spec, sourcing, purchasing, receiving, inspecting, familiarizing, assembling, installing, configuring, testing, there’s likely another $2000 or more to add, and then the shipping, customs brokerage, cable mod, battery box mod, hardware. When all is said and done, I bet that 100 Ahr LFP battery had a real cost of $2500 to $3000.

Remember I do this kinda stuff for customers all the time, for years and years and years. Of course my time is worth lots more, but I can do it much faster just due to same stuff different day, been here, done that, many, many, many times.

This is what some folks don’t get about DIY, they’re trading their time for money (hired labour savings). We can always make more money...

For those who prefer to work on their boats instead of sail them, no problem, but it doesn’t change the real cost. They could just as easily be using that time to generate additional income.

you obviously don't do Lfp installs often . Mph install took about an hour to build the bank . All done in my spare time . ( I'm retired.)
you really over think things way to much. Considering that you think it costs over 3k to install a simple 100ah battery asp nd set the solar charge controller to stop charging at 13.8v . You definitely over value your time . I have posted in the Lfp cost thread all of my system build parameters as well as their costs. Ask john he has seen it .

Considering how much you wrote on the background items . (research, product spec, sourcing, purchasing, receiving, inspecting, familiarizing, assembling, installing, configuring, testing, ) you obviously have not done any of this . I think I spent an hour or so to accomplish every part of that list not counting the researching. That was a weekend leisurely surfing the web.

He testing did take a full day to charge to 14.0v and then the discharging to measure capacity. But I do that annually anyway ( my sole maintenance on the bank)
if you feel like that little 100ah bank is worth charging 2 to 3 thousand for that is your choice.
( the bank cost was cells 128 . Shipping via air freight 180 the bms was 15 for a total cost delivered to me at my address of 323 the custom box I built cost nothing due to leftover materials from other home projects. ) if you honestly want to know more and see the pictures to prove what I say I did look at my boat refit page . You might even find something that peaks your interest

Aside from pushing Fla so hard .

[newhaul]

Originally Posted by john61ct

We all see reality through the lenses of our own personal value systems.

Some greatly prefer spending time on "leisure" activities that others abhor, over whatever they've chosen to earn money.

In the end, economic calculations are just one dimension of life, and a very shallow one.

bingo you get it . Btw I really enjoyed my work on many vessels from a little 7 ft skiff I built on a Saturday with my boys when they were young . All the way up to the largest navy vessels afloat. I thoroughly enjoy the work on my own restoration project ( that I will own till I pass )

a couple hours puttering around in the shop now will save me hundreds of hours of maintenance articles I didn't like doing in the past is priceless.
But of course YMMV

[ramblinrod]

Originally Posted by newhaul

you obviously don't do Lfp installs often . Mph install took about an hour to build the bank . All done in my spare time . ( I'm retired.)
you really over think things way to much. Considering that you think it costs over 3k to install a simple 100ah battery asp nd set the solar charge controller to stop charging at 13.8v . You definitely over value your time . I have posted in the Lfp cost thread all of my system build parameters as well as their costs. Ask john he has seen it .

Considering how much you wrote on the background items . (research, product spec, sourcing, purchasing, receiving, inspecting, familiarizing, assembling, installing, configuring, testing, ) you obviously have not done any of this . I think I spent an hour or so to accomplish every part of that list not counting the researching. That was a weekend leisurely surfing the web.

He testing did take a full day to charge to 14.0v and then the discharging to measure capacity. But I do that annually anyway ( my sole maintenance on the bank)
if you feel like that little 100ah bank is worth charging 2 to 3 thousand for that is your choice.
( the bank cost was cells 128 . Shipping via air freight 180 the bms was 15 for a total cost delivered to me at my address of 323 the custom box I built cost nothing due to leftover materials from other home projects. ) if you honestly want to know more and see the pictures to prove what I say I did look at my boat refit page . You might even find something that peaks your interest

Aside from pushing Fla so hard .

No, I don’t overthink things, I’m just a realist and cognizant of the real cost of doing things, and very adept at recognizing over and under exaggerated claims.

Whether one chooses to recognize it makes no difference, spending ones time trying to do something they could hire someone else to do better, faster, cheaper, is a waste of valuable finite time.

I used to do my own house and automobile maintenance and repairs. Now I understand my time (including leisure time) is spent much more wisely hiring others to do this for me.

[evm1024]

Any scenario that >>requires<< that I run my engine or generator because of a few cloudy days is a failed system.

LiFePO4 allows freedom from running ICE.

But of course that is just my view on it. Some my have differing opinions. That is fine with me.

[john61ct]

Yes, the high CAR rate means a few hours a week from ICE

which I'm running anyway,

fulfills all my energy needs, thus

means I don't need to spoil my boat's lines and elegance with solar panels.

[evm1024]

Some really need to point as close as the wind as possible. Others prefers the elegance of their boat unspoiled. No solar for them and more power to them. A few hours once in a while into LiFePO4 with its high acceptance rate and lack of problems when not reaching 100% (whatever that is, Let's not quibble) make ICE charging a viable solution to >>Their<< use case. Much more so than lead acid and all its charging needs.

For others such as down wind sailors in the tropics, running an engine for hours in an already hot environment is a very poor solution. Ample solar and LiFePO4 provide a very satisfactory solution. With enough solar and LiFePO4 one could even run a water maker to meet ones daily needs without resorting to ICE and the heat involved. Not to mention the cost of operation and wear and tear that comes with it.

Many solutions for many use cases. I think that we all can live with that. So we are at the basics in agreement.

Here is a photo of my boat. As you can see I do not have any solar on yet so in some ways I am speaking theoretically. I would love to see a photo of your boat - You speak fondly of it (don't we all). Elegant lines can be so moving.

[newhaul]

Originally Posted by evm1024

Some really need to point as close as the wind as possible. Others prefers the elegance of their boat unspoiled. No solar for them and more power to them. A few hours once in a while into LiFePO4 with its high acceptance rate and lack of problems when not reaching 100% (whatever that is, Let's not quibble) make ICE charging a viable solution to >>Their<< use case. Much more so than lead acid and all its charging needs.

For others such as down wind sailors in the tropics, running an engine for hours in an already hot environment is a very poor solution. Ample solar and LiFePO4 provide a very satisfactory solution. With enough solar and LiFePO4 one could even run a water maker to meet ones daily needs without resorting to ICE and the heat involved. Not to mention the cost of operation and wear and tear that comes with it.

Many solutions for many use cases. I think that we all can live with that. So we are at the basics in agreement.

Here is a photo of my boat. As you can see I do not have any solar on yet so in some ways I am speaking theoretically. I would love to see a photo of your boat - You speak fondly of it (don't we all). Elegant lines can be so moving.

well here is a shot of my last boat the islander 24 and secondly my current columbia 29.

Showing my solar on both. All panels are 100 watt mono

[ramblinrod]

Originally Posted by evm1024

Any scenario that >>requires<< that I run my engine or generator because of a few cloudy days is a failed system.

LiFePO4 allows freedom from running ICE.

But of course that is just my view on it. Some my have differing opinions. That is fine with me.

????? Everything else equal, any battery system incorporating solar charging will need some form of alternate charging after a period of no sun. Batteries do not generator power. They only accept it, store it, and discharge it.

The high acceptance rate of LFP is virtually useless in a solar charging regime, doesn’t come into play, as the charge profile for solar is typically around 5 A / 100W around noon, and then slowly diminishes during the afternoon until sunset, similar to the diminishing acceptance rate of FLA. A pretty nice technological match. (The higher acceptance rate of LFP cannot be utilized unless the solar charging system is way oversized to actual charging needs, and the actual recommended acceptance rate to not hurt the longevity of LFP is not much higher than FLA (in the bulk charging stage, earlier in the day, when the solar output is there to use it.)

[john61ct]

What a crock.

There is no "way oversized to actual charging needs" other than windage, budget and aesthetic taste of the owner.

The whole point of going for big panel capacity is avoiding ICE even when insolation is poor.

After CV stage is reached FLA acceptance declines, can still take 5+ more hours to get to Full, which is **required** for longevity. That acceptance never gets over 0.2C,

while with LFP the recommended 0.4C charge rate (double that, and even 5x that at 1C is fine with hot cells)

never slows down until a few minutes before Full.

But there is also **no need** to ever get anywhere near Full with LFP, and in fact avoiding it is better for longevity!