LiFePO4 vs FLA - The Real Deal

[john61ct]

I agree FLA is a fine choice for many.

If anyone is "bashing" it, fan-boy arguing for **any** one alternative as The One True solution for all use cases,

I just recognize their ignorance and move on, why argue?

Same with someone arguing "FLA is the best" for all use cases.

Pointless trying to change someone's religious beliefs.

[john61ct]

I see my lithium packs as independent of any one installation.

From one boat to another, use on land in my off-grid cabin, camper truck.

Not like a mast or rudder that is an integral part of a specific boat.

Same with the DCDC charger, lets me precisely refill any bank from any old nominal 12V source.

[Delfin]

Originally Posted by ramblinrod

Because there are a whole lot of people making wild claim in favour of LifePO4 and bashing FLA, and it is pretty much completely unwarranted.


If someone wants to buy LiFePO4 because they think it makes them "cool" I will gladly sell them some, after advising that in 95% of cases, they would be way better off with FLA.

Well, actually my recommendation works. ;-)



See. (So why pay 6 - 10 times as much for LiFePO4 that have to be shipped half way around the world, as one can for FLAs at the shop around the corner.



Then you are doing something wrong with FLA banks; probably chronically undercharging.

If you use my ratios, charged properly, the FLAs will last 5.

Your LiFePO4s are not likely to last 20. Be happy if you see 10.

So if the LiFePOs were only 50% more than FLA (they are much more but for arguments sake), then maybe, but a greater than 7.5 year break even is considered a pretty bad investment, especially if the LiFePO4 batteries are not "money-back" or "full replacement" guaranteed to the break even point. (They aren't).

While I agree that FLA can last quite a long time if properly charged as you suggest, you have completely missed the point of why LiFePOs may be a superior choice for many. If you would like to cut the time it takes to re-charge your bank to 25% of what it was before, than LiFePO may be worth the cost. If you would like to have 26+ volts to 20% SOC rather than 24+ volts to 50% SOC, then LiFePO may be worth the cost. If you would like to have batteries that weight 25% of what FLA of the same usable capacity, then LiFePO may be worth the cost.

You're comparing a pickup truck to a moped and by focusing on only one feature of FLA vs. LiFePO - purchase cost per amp - you can reach your conclusion. A more complete analysis doesn't support that conclusion.

[john61ct]

Especially since the price per AH for both types vary so wildly by location.

And the priority weighting for each factor varies by use case and owner preferences.

[Delfin]

Originally Posted by 44'cruisingcat

Sure, presenting an argument is fine. And in fact I agree that at US prices, it's difficult to justify lithiums in financial terms. The other benefits would have to be important to you as well.

But, to say that because lithiums CAN be charged in one hour means they MUST be, requiring huge additional investment in generator and battery chargers is frankly, stupid, and seriously reduces the credibility of the OP.

Add to that the claim that lithium battery banks need to be significantly bigger than the LA they replace.... well you really have to wonder...

The last statement, if made, simply indicates the poster has no useful knowledge regarding LiFePO batteries.

For us, the primary reason for replacing an AGM bank with lithium was reduced charging time. I had people advise me that with the 600 Ah Li bank I was installing to replace a 1280 Ah AGM bank (we use around 300 Ah per day), I should toss my Trace 4000 over the side and install 300 Ah of charging capacity to take advantage of lithium's ability to soak up a great deal of current with no taper. Since we also use a lot of fresh water (2 dogs, fresh water flush, showers, high pressure fresh water washdown, etc.), I can run the genset for 3 hours, make 75 gallons of water and recharge the Lithium. No great pain there. To replace 300 amps in my former AGM bank, the genset would have to run for a minimum of 8 hours to completely recharge, and that is the only way to make FLA last - fully recharge them. And no, I don't want to festoon the boat with solar and wind generators, but that's just me.

Li isn't for anyone, especially if up front capital investment is more important than living with the consequences of a lower up front capital expense. But if you spend a lot of time away from docks, and don't like reducing the life of a genset by using a lot of hp to generate the piddling amount of current an FLA will accept through half of its charge cycle, then Li may be an option if you can afford it.

[Delfin]

Originally Posted by john61ct

Especially since the price per AH for both types vary so wildly by location.

And the priority weighting for each factor varies by use case and owner preferences.

Absolutely correct. Some would prefer to build their own bank and they can save a lot of $. Others may prefer to let someone else do that and pay for the service.

[a64pilot]

Everything has a value.
I’m sure a Rolex Presidential is an excellent watch, but I’m not buying one, cause the value it represents for me isn’t worth the price, same say for a Tesla and or many other examples.
From a curious glance, using US prices, it would seem if one avoids EBay off brand Lithium (cause I don’t know enough to know which to avoid) and buys from a trusted supplier in the US, prices are at least 6 times per AH over lead, and as much as 9 times as much. And this is batteries only, to say nothing of the other required equipment.
For me at the present time, the value isn’t there, yet.

For me they are for now in the same category as laminate sails, unquestionably better, just don’t have value for me.
Good Dacron sails are all I need.
Now I’ll keep watching in the hope that prices come down enough so that when my current Lifeline bank dies, I’ll go Lithium.
There are several distinct advantages, just for me they are not enough to justify the cost is all, cause just like my Dacron sails, they get me to where I’m going, maybe not quite as fast, but certainly for a fraction of the cost

You mileage may vary of course.

[thinwater]

Originally Posted by newhaul

your not looking at it in the correct way. The weight savings means another 50 ft of anchor chain. Or more fuel or more supplies.
Bilge on a 29 ft sailboat you don't put stuff in the bilge. Its already filled with fuel tanks and water tanks.

From a purely money point 86 USD is enough for me to pay my license fees for 4 years on my boat.

But you paid how much to save $86? That is the point. Just sayin' it's a lot of cost for something that is not huge for most people. And perhaps there are cheaper ways to save the weight.

[thinwater]

Originally Posted by john61ct

Not at all stupid.

Define **your** 0% and 100% by voltage.

The bottom will not be exact since amp rates will vary, but mine at 11.9V (2.975Vpc) is usually within around 10% of the 20-hour rating, compared to any harmfully low point.

When you need the top to be precise,

as in calibrating your AH counting SoC meter (e.g. 712-BMV)

use a consistent charging amp rate, and Hold Absorb until a specific endAmps setpoint.

Mine is 13.8V (3.450Vpc) held until .025C (2.5A per 100AH capacity.

In daily cycling I "just stop" at that voltage, no Hold Time at all.

You really cannot use voltage for SoC on the way down.

A properly configured and frequently reset coulomb counting SoC monitor like the BVM above works just fine to gauge your usage.

And of course your load circuits should have LVD cutoffs as appropriate, set according to how essential and how high-current the loads are.

So your PC and entertainment systems cut off before nav / safety gear, and the fridge somewhere in between.

The actual BMS protection is much lower, and should never be triggered in normal use.

How do you compensate for temperature? The voltages listed are only valid in a narrow range.

[newhaul]

Originally Posted by thinwater

But you paid how much to save $86? That is the point. Just sayin' it's a lot of cost for something that is not huge for most people. And perhaps there are cheaper ways to save the weight.

actually I paid 2.48 per ah delivered to me . In the form factor I wanted. 2x 100 ah packs with internal bms. About the same size as my cordless drill case. And mountable in any position and spot I want to put them.
I'm looking at strapping them on either side of the engine compartment on the bulkhead.
Actually thinking of getting three and using the third as a portable charge pack for my toys.
( tablets and cell phones Hand GPS etc.)
no real change to my charging sources just set controllers to appropriate cut out voltage .
Small Fla for engine starting no alternator mounted dynostarter to keep start battery happy.
( hand crank in event of dead start battery.)

[ramblinrod]

Originally Posted by newhaul

actually I paid 2.48 per ah delivered to me . In the form factor I wanted. 2x 100 ah packs with internal bms. About the same size as my cordless drill case. And mountable in any position and spot I want to put them.
I'm looking at strapping them on either side of the engine compartment on the bulkhead.
Actually thinking of getting three and using the third as a portable charge pack for my toys.
( tablets and cell phones Hand GPS etc.)
no real change to my charging sources just set controllers to appropriate cut out voltage .
Small Fla for engine starting no alternator mounted dynostarter to keep start battery happy.
( hand crank in event of dead start battery.)

As I asked previously, please identify your source at this price

[john61ct]

LFP's temperature compensation coefficient is so close to 1.0 I just disable that feature.

Most charge regulators don't even let you adjust it that finely anyway.

But if you have links to specs for the precise coefficient for the leading manufacturers, I'd like to check it out.

Obviously temperature **protection** is critical, but that's a very different topic.

[newhaul]

Originally Posted by ramblinrod

As I asked previously, please identify your source at this price

I do believe I posted the link to the thread that explains everything including ongoing test results. But here it is again . http://www.cruisersforum.com/forums/...o4-194142.html

[ramblinrod]

Originally Posted by Delfin

While I agree that FLA can last quite a long time if properly charged as you suggest, you have completely missed the point of why LiFePOs may be a superior choice for many.

If you would like to cut the time it takes to re-charge your bank to 25% of what it was before, than LiFePO may be worth the cost.

If one prefers solar and wind charging when available, the benefit of faster LiFEPO4 charge rate via alternator may be negligible.

In fact, the charge rate may be identical (alternator max output) over the charge cycle except the last 20%.

Simple solution, charge fully with wind and solar, whenever possible (and it usually will be using the ratios of charge sources I posted).

On rare occasions where it is not possible to charge fully via wind and solar, charge up to 80% SOC with the alternator early in the day, so the wind and solar that is available will charge the last 20% over the course of the day.

In reality, this will result in the same amount of ICE charging regardless of technology.

If you would like to have 26+ volts to 20% SOC rather than 24+ volts to 50% SOC, then LiFePO may be worth the cost.

Feature and benefit are two different things. LifePO4 have lots of claimed "features". My position is that those features do not translate into real world benefits to the extent to make them cost justifiable "worth it".

If someone buys something because they want it, without cost justification, that is perfectly fine.

My point is, if the cost justification isn't there, they aren't "worth it" they are just desired "at any cost".


Very few can really justify the cost of a Lambourghini. Yet they are sold, just not to the mainstream who can't justify it any which way from Sunday.


Many are pushing LiFePO4, claiming they are cost justifiable, and "worth it". IMHO, this simply isn't true. YMMV.

If one truly analyses the circumstances, LiFePO4 is rarely "worth it", just desired.

If you would like to have batteries that weight 25% of what FLA of the same usable capacity, then LiFePO may be worth the cost.

As shown in the example I provided, the LiFePO4 provided only a 50% weight savings over an equal size and capacity LiFePO4 battery.

You're comparing a pickup truck to a moped and by focusing on only one feature of FLA vs. LiFePO - purchase cost per amp - you can reach your conclusion. A more complete analysis doesn't support that conclusion.[/QUOTE]

I disagree.

I believe I have performed adequate analysis and have drawn the conclusion that while LiFePO4 have various "marketing features" over FLA, the reality is, most potential purchasers will not realize actual "benefits" that are "worth it".

If nobody on the forum is drawing this reality to the forefront, many may be "roped" into purchasing products that are very costly, and really don't benefit them that much.

For someone with chronic FLA battery issues, if they just review their capacity, charge sources, and practices, and adjust as appropriate, their problems will likely be solved 95% of the time, without switching battery technology at all, for a lot less money.

[newhaul]

Originally Posted by ramblinrod

If one prefers solar and wind charging when available, the benefit of faster LiFEPO4 charge rate via alternator may be negligible.

In fact, the charge rate may be identical (alternator max output) over the charge cycle except the last 20%.

Simple solution, charge fully with wind and solar, whenever possible (and it usually will be using the ratios of charge sources I posted).

On rare occasions where it is not possible to charge fully via wind and solar, charge up to 80% SOC with the alternator early in the day, so the wind and solar that is available will charge the last 20% over the course of the day.

In reality, this will result in the same amount of ICE charging regardless of technology.
.

that's just the point you don't seem to understand. I can and do fully charge my Lfp to my satisfaction daily purely on alternative energy sources. There were times in winter that would never happen with Fla I had. And one winter of PSOC will kill a decent Fla bank. A Lfp doesn't care.