LiFePO4 vs FLA - The Real Deal

[senormechanico]

Originally Posted by thinwater

I would love to see good data too. That is EXACTLY why I started that thread.

[snipped]

From what I'm reading, charging Li below freezing is a dodgy area, and yet my boat (and many others) will it at dock in those conditions for months. I also cruise some in the winter.

Here's something about Cold Charging.


https://www.designnews.com/electroni...53122864258157

[gmakhs]

From what I see I do agree that lithium's are better batteries in general .
But I can see a good reason for the price difference

[newhaul]

Originally Posted by CatNewBee

There are fuel cells running on methanol out there, a waste product of moonshining on the first few litres...

This gives this thread a surprising turn I guess... [emoji12]

what do you think I used to start my diesel stove under the still with

[ramblinrod]

Originally Posted by 44'cruisingcat

I'm sure you know this is completely wrong.

Actually, NO, I believe it is very accurate.

With lithiums you dont need to run the generator to fast charge for the first 80% of the charge cycle to allow for the slowness of the last 20%.

With LA you do.

Incorrect, with either technology, if your charging system is not supplying the current to meet loads, eventually one must apply alternative charging (alternator for example).

If one has a 100 A-hr daily load, and a 100 A-hr LifePo4 bank (no reserve capacity as many have suggested) , they most definitely will be switching to alternator.

Under the same circumstances, if one has a FLA bank with 100% proper reserve capacity, at 50% discharge, they may choose to switch on the alternator.

Yes, the properly sized FLA bank owner has a choice the undersized LifePO4 owner doesn't.

I do this all the time with my FLA bank, if it is at 50% and I think it will only hit 30 or 40% before I expect the sun and wind come up to fully charge the bank that day, I don't turn on the alternator.

The LifePO4 owner under the same circumstances, has to, no choice, except to sit in the dark with no power until the sun and wind comes up.

With LA, you know that going to bed with the batteries at 80% is going to hurt them down the line.

Incorrect! I do exactly this if I expect the charge capacity the following day will bring them back up to 100%. Doing this with a frequency of about 2 days out of 7, has negligible impact on battery life.


Doing it constantly will impact life expectancy, but as I said, this is not a battery technology problem, it is a charge capacity problem.

Having very expensive LifePO4s one cannot regularly charge to 100% is a much larger waste of money in $/A-hr capacity not utilized.

In either case, adding charge capacity will solve the problem. Changing to a very expensive battery technology to purposefully underutilize, doesn't.

In practice, if one doesn't have enough solar and/or wind, and can only charge 80% of their daily consumption, they will run down their batteries and be charging by alternator every day, ESPECIALLY if they have no LiFePO4 reserve capacity.

[44'cruisingcat]

Originally Posted by ramblinrod

Actually, NO, I believe it is very accurate.




Incorrect, with either technology, if your charging system is not supplying the current to meet loads, eventually one must apply alternative charging (alternator for example).

And there you go, shifting the goalposts once again.....

How about the normal boat, with enough solar to recharge the batteries in a day?

With lithiums the batteries accept all the solar can deliver, right up till theyre full.

With lead, as you get up around 80% the charge rate slows right down. The last 20% could take hours. But the sun doesn't stay up forever.

So to give the solar long enough to dribble in the last 20% in the afternoon, you run the genset in the morning. Or you need to add significantly more solar to get the job done.

With lithiums you dont need to. In fact, due to their efficiency, switching to lithiums is like adding 10% to your solar anyway.

[ramblinrod]

Folks, the point is, I see issues like this all the time.

Somebody has a poorly balanced electrical system and pour charging practices.

They have to replace their FLA bank frequently.

Finally they get fed up and:


1. Ignore that the primary problem may be due to their own lack of attention or bad practice.

2. Research different product solutions.

3. Install an alternate (and often more expensive, sometimes extremely)battery brand, model, capacity, or chemistry.

4. Install a higher output alternator with smart regulator.

5. Install several hundred Watts of solar.

6. Install a wind generator.

7. Install a battery monitor.

8. Watch there batteries much more closely and reduce the incidence of chronic undercharging.

9. Claim that the new batteries are way more better, they now have all the power they need.

The truth is, had they have done the same things, with the original battery brand and model, they would be in exactly the same boat (har), all of the power they need AND saved the cost of the alternate and more expensive battery technology.

Again, I don't care what anybody chooses for battery technology.

I am attempting to help folks understand, that a lot of the claims they may here about the real world benefits of LiFePO4s, probably will not be that significant.

And if they do make all of these changes, they should not be claiming they are a result of battery change. It isn't. It is a result of balancing capacity and charging capability to demand, and LiFePo4s may not be the answer at all, and could be a very expensive mistake.

I am glad that one poster at least, very knowledgeable in the field of LifePO4s, has acknowledged that for the majority of cruisers, they would be a bad idea on a cost/benefit basis, or even a benefit alone basis. It really wouldn't make much or any difference to their lives, except the negative impact on their finances.

Why do I care?

Well, for one thing, as a boater, I like to contribute what I can to the boating community.

For the second, I consult boat owners on the best electrical energy storage and charging solutions to meet their needs. In almost all cases, I have to go through this entire discussion, because they heard how "great" people were claiming LiFePO4s are.

I could be unethical, and just sell them some really expensive gear and make a crapload of money at their expense.

Instead, I help them choose, the "best value" solution instead of the "most expensive".

Which can be LifePO4, especially where weight is very critical. But in reality, in most cases, the weight difference is negligible.

[CatNewBee]

Originally Posted by ramblinrod

Actually, NO, I believe it is very accurate.




Incorrect, with either technology, if your charging system is not supplying the current to meet loads, eventually one must apply alternative charging (alternator for example).

If one has a 100 A-hr daily load, and a 100 A-hr LifePo4 bank (no reserve capacity as many have suggested) , they most definitely will be switching to alternator.

Under the same circumstances, if one has a FLA bank with 100% proper reserve capacity, at 50% discharge, they may choose to switch on the alternator.

Yes, the properly sized FLA bank owner has a choice the undersized LifePO4 owner doesn't.

I do this all the time with my FLA bank, if it is at 50% and I think it will only hit 30 or 40% before I expect the sun and wind come up to fully charge the bank that day, I don't turn on the alternator.

The LifePO4 owner under the same circumstances, has to, no choice, except to sit in the dark with no power until the sun and wind comes up.



Incorrect! I do exactly this if I expect the charge capacity the following day will bring them back up to 100%. Doing this with a frequency of about 2 days out of 7, has negligible impact on battery life.


Doing it constantly will impact life expectancy, but as I said, this is not a battery technology problem, it is a charge capacity problem.

Having very expensive LifePO4s one cannot regularly charge to 100% is a much larger waste of money in $/A-hr capacity not utilized.

In either case, adding charge capacity will solve the problem. Changing to a very expensive battery technology to purposefully underutilize, doesn't.

In practice, if one doesn't have enough solar and/or wind, and can only charge 80% of their daily consumption, they will run down their batteries and be charging by alternator every day, ESPECIALLY if they have no LiFePO4 reserve capacity.

reserve capacity is a mind set.

With FLA you have 50% usable capacity, the rest is sacrificing your battery life span.

Wit LFP you have between 80% and 120% usable capacity depending on the manufacturer on a new battery. after that point you have the same situation, the battery delivers power, but degrades quickly and you sacrifice life span - may be a little worse than deep discharge of an FLA, because more expensive and quicker voltage drop (shoulder).

If your life depends on it, no problem to squeeze some more Ah out. You should not hit that areas on both technologies regulary on purpose. It is NOT reserve capacity, it is like a disposeable battery. You do irreversible damages to your bank.

For the sizing. Replacing a FLA by same size LFP gives you up to 100% more usable capacity without sacrificing life span, taking a smaller LFP gives you the same usable capacity for a comparable price. LFP are about 2 times the price of a branded AMG or GEL (in the EU).

btw, the 50% reserve you are claiming is not usable, you cannot discharge a FLA to zero while running 12V gear, the voltage drop simply will prevent your electronics and devices to operate at this SOC.

[john61ct]

Originally Posted by thinwater

The temperature thing is boiled into the physical chemistry of batteries

But **what** "temperature thing" are you referring to?

the impact of batt temp on capacity, discharge performance

the impact of it on battery longevity

the danger of charging at low temps

?

None of these have anything to do with the technical term "temperature compensation", which is the need to adjust the charging voltage setpoints with the battery temperature.

[john61ct]

There really is little point trying to show some people the errors in their thinking, just a waste of time and mental bandwidth.

[john61ct]

Originally Posted by CatNewBee

One fact is, LFP can absorb much more current, and this puts more / longer high load on the alternator, usually the alternators are designed to re-charge a start battery after cranking the engine and provide some Amps for the bord electric system, like lights, fans, fuel pump etc.
…
In most cases it is just coincidence, your system comes to age, yor FLA were dying maybe the second time and you are sick of investing again in an old technology, the alternator brushes are wearing out in the mean time, then you drop in fresh LFP batteries eventually with a higher capacity and the alternator just degrades faster and needs a service / replacement.

No, a brand new alt working as designed for lead can be completely fried in one hour of being hooked up to LFP.

This is not a problem with LFP, but of system design.

The current demanded of the alt must either be throttled at source, e.g. a DCDC charger,

or the alt converted to a proper external VR like Balmar MC-612, which temp sensors will derate amps as heat rises.

FLA of any size or SoC will rarely be able to do this


> set to 14.2V, safe for lithium

Safe but not conducive to longevity

The BMS OVD function should never be used to control routine charging. It is a failsafe for if/when the normal gear that does fails.

[Dockhead]

Originally Posted by a64pilot

Dockhead,
In your case I’m still thinking that a fuel call and LA make sense, the generator can hammer in the amps when the bank can take it, and the fuel cell dribble it in after the acceptance rate drops, just it requires a fuel cell that can handle the house load, and have room left over to top off the batteries.
Same if you use a Lithium bank to finish charge, and I take it, your house loads are large.

Sure, but if you've looked at actual commercially sold fuel cells -- doesn't make sense.


But a hybrid bank with lithium . .. . Even a SMALL lithium bank, sized just for that purpose. That would be really cool and totally solve this one main issue with lead batteries.

[john61ct]

Originally Posted by Dockhead

But a hybrid bank with lithium . .. . Even a SMALL lithium bank, sized just for that purpose. That would be really cool and totally solve this one main issue with lead batteries.

This is the thread discussing that idea

http://www.cruisersforum.com/forums/...en-206424.html

[newhaul]

Originally Posted by ramblinrod

Folks, the point is, I see issues like this all the time.

Somebody has a poorly balanced electrical system and pour charging practices.

They have to replace their FLA bank frequently.

Finally they get fed up and:


1. Ignore that the primary problem may be due to their own lack of attention or bad practice.

2. Research different product solutions.

3. Install an alternate (and often more expensive, sometimes extremely)battery brand, model, capacity, or chemistry.

4. Install a higher output alternator with smart regulator.

5. Install several hundred Watts of solar.

6. Install a wind generator.

7. Install a battery monitor.

8. Watch there batteries much more closely and reduce the incidence of chronic undercharging.

9. Claim that the new batteries are way more better, they now have all the power they need.

The truth is, had they have done the same things, with the original battery brand and model, they would be in exactly the same boat (har), all of the power they need AND saved the cost of the alternate and more expensive battery technology.

Again, I don't care what anybody chooses for battery technology.

I am attempting to help folks understand, that a lot of the claims they may here about the real world benefits of LiFePO4s, probably will not be that significant.

And if they do make all of these changes, they should not be claiming they are a result of battery change. It isn't. It is a result of balancing capacity and charging capability to demand, and LiFePo4s may not be the answer at all, and could be a very expensive mistake.

I am glad that one poster at least, very knowledgeable in the field of LifePO4s, has acknowledged that for the majority of cruisers, they would be a bad idea on a cost/benefit basis, or even a benefit alone basis. It really wouldn't make much or any difference to their lives, except the negative impact on their finances.

Why do I care?

Well, for one thing, as a boater, I like to contribute what I can to the boating community.

For the second, I consult boat owners on the best electrical energy storage and charging solutions to meet their needs. In almost all cases, I have to go through this entire discussion, because they heard how "great" people were claiming LiFePO4s are.

I could be unethical, and just sell them some really expensive gear and make a crapload of money at their expense.

Instead, I help them choose, the "best value" solution instead of the "most expensive".

Which can be LifePO4, especially where weight is very critical. But in reality, in most cases, the weight difference is negligible.

watt hour for watt hour Lfp are better imho.
When you do the math prices fall much closer to each other and when amortized over the life they start coming into their own.

[ramblinrod]

Originally Posted by CatNewBee

reserve capacity is a mind set.

If one dips and FLA bank down to 30% of even 20% SOC on occasion, and charges it right back up again within a day or two, no issue, negligible impact on lifespan. Doing it regularly and not charging it up could hurt them. But this is a clear indication of insufficient charge capacity or bad charge practice, (with respect to monitoring and using auxiliary charging as necessary).

Under the same conditions, one would have dipped below the normal usable capacity of the LiFeP04 (if no reserve capacity was provided) and either hurt them, or relied on safety features to prevent it. Either way, without intervention they would be in the dark.

As I said very early in thread, a design with no reserve capacity is bad design.

What if your life doesn't depend on it, but you are just tired of sitting in the dark after spending all this money on these batteries.

So if one is using 120% of the capacity of a LiFePO4, how many additional A-hrs can they draw, from a 100 A-hr battery, before it is pooched, dead, for good, shot, never to be used again?

As I said very early in thread, a design with no reserve capacity is bad design.

With FLA, if one dips into reserve capacity on occasion and charges right back up again, it has negligible impact on life expectancy.

This is important, as loads can very from day to day.

No reserve capacity would be very foolish.

With no reserve capacity on a LifePO4 based system, expect to be using the alternator a lot, or sitting in the dark a lot, if sun and/or wind is down.

OK, "reserve capacity", is additional capacity to meet occasional additional load.


So if on occasion one can dip into a FLA bank down to 20% without particularly hurting it, and they can dip down to 20% of a LiFePO4 bank without hurting it, where is the benefit.

Because one can size the LiFePO4 bank to utilize down to 20% on an average day? No as I said before, again and again, because it is true, you still need reserve capacity with LiFePO4.

if one needs 100 A-hr of capacity average, and daily load may fluctuate +/-50%, a good choice for FLA would be 200 A-hr. A good choice for LifePO4 would be 200 A-hr. This way NEITHER technology is being discharged so low it will hurt it. 4,

In the case of LiFePO4, you can leave it at a low state for a long time IF YOU DON'T need any electricity, else you need to start charging as soon as you can.

In the case of FLA, you need to charge it back up soon to avoid hurting it. It makes little difference, because you also need to charge it back up soon as you can, because you will need electricity again tomorrow, and the next day, and the day after that, and so on.

In either case it makes no difference, if you discharge the battery to a low state, you need to charge it back up again quickly, OR YOU WILL RUN OUT.

btw, the 50% reserve you are claiming is not usable, you cannot discharge a FLA to zero while running 12V gear, the voltage drop simply will prevent your electronics and devices to operate at this SOC.

Nobody said all of the reserve capacity could be used, but you can use a charge cycle of 100-20% on occasion if need be, just as you can with LiFePO4. You cannot design for 100-20% capacity of LiFePO4 based on average consumption, or you will be firing up the alternator every signle day you go below 20%, and hurting those 9 x the price of standard FLA batteries.

[newhaul]

Originally Posted by ramblinrod

Nobody said all of the reserve capacity could be used, but you can use a charge cycle of 100-20% on occasion if need be, just as you can with LiFePO4. You cannot design for 100-20% capacity of LiFePO4 based on average consumption, or you will be firing up the alternator every signle day you go below 20%, and hurting those 9 x the price of standard FLA batteries.

wrong
Here is Maine sails reply to this 50% reserve bs http://www.cruisersforum.com/forums/...ml#post2705532


What you're missing is what happens to batteries in the real world outside of an extrapolated table created from white-glove lab data.

Routinely dipping to 80% DOD on lead acid, other than GEL (they actually handle this marginally well), in the real world is just not good for the batteries. I see this repeatedly in actual capacity testing of used marine batteries.

This is not to say never dip to 80% DOD. The occasional dip to 80% DOD is fine, and can even be somewhat healthy, provided you recharge ASAP to 100% SOC immediately there after.

Going to 80% DOD routinely, in my experience, (based on actual testing) just does not result in the energy throughput the curve depicts, not even close. Why? We're not operating our banks in a laboratory. One can assume this is why nearly every LA battery maker, including Trojan, Lifeline, East Penn etc. suggest 50% DOD max. It's because I suspect they do actually know what happens outside the lab. A bottom DOD of 50% helps minimize impact on reputation I suppose..

Lifeline initially marketed their batteries for 80% DOD and it left a bad taste for many AGM early adopters. Lifeline has since revised their suggested DOD to 50% max. A result of real world use vs. lab data.??

I was on a transient boat at the end of July for an "engine issue" (plugged 2 micron primary). The owner had "motored all day", a 52nm run with no wind or wind on the nose, before the engine slowed repeatedly then died altogether. He was able to limp in under sail..

During the bleeding process the bank died on the second start attempt (one bank no other bank on-board). When I looked at the date code on the G-31 batteries they were dated March of 2018 or basically brand spankin' new.

When I asked the owner how they had been performing he said they were great in April, May and June but now they were "really bad". After a few questions he explained to me that his normal "it's time to recharge" voltage was approx 11.6V.

The batteries were so destroyed, in just a couple months, that even when at a 10.67V open circuit voltage, after the starting attempts, when we got them jumped the voltage immediately jumped up to 14.2V from a 0% SOC voltage reading, with only a 60A alternator. This is completely bypassing the bulk charge stage due to sulfation. This had been his third jump-start of the trip and he assumed it was bad cables or connections.

This behavior is due to sulfation and no matter how long he charged the bank it was just done. Even after a rather aggressive EQ process the two batteries sagged to 11.2V under a measly 10A load the next morning.

Two destroyed West Marine / East Penn G-31 batteries in just a few months. He simply shrugged and said "I'm going to return them to West Marine, these batteries suck." This was not the fault of West Marine or the battery maker but rather due to overly deep cycling on a cruising boat without attaining 100% SOC often enough.

In contrast I have customers who shallow cycle, charge properly and who get 10+ years out of deep-cycle LA batteries and a few GEL banks that have gone over 15 years.

All I can say, and it's not my money I am trying to save here its yours, is don't routinely deep-cycle to 80% DOD unless you have batteries such as a quality GEL, Firefly, or others that are specifically designed for it. Testing of real world marine use batteries shows me the cycle life graphs are simply not translatable to the real world in terms of the energy throughput they suggest.