LiFePO4 vs FLA - The Real Deal

[44'cruisingcat]

Originally Posted by daletournier

For the record I was actually trying to say I understand performance cat owners much preferring Lfp due to the desire to be lighter, as is the topic of another thread running. I didn't say you can't carry a bigger bank, I didn't say your boat would sink if you did,
I was saying you probably don't want to carry 900ah (which i have) , being a performance cruising cat owner. This was not intended as an insult to you or your boat, which I like alot BTW.

In regards to typing c44, it was a typo, sorry about that, in regards to your aggression, it's real easy behind a keyboard and it's cowardly. Feel free to put me on an ignore list or just ignore my posts if they cause you issues. If you do respond then great, your a knowledgeable bloke, and I read what you say with interest but please don't be rude. People are entitled to view the world differently to you.

Also most here including me didn't buy our batteries in Australia. Most have found up to date Lfp to be much more expensive than wet cell trojans such as I use.

You seem to keep seeing agression where there's none.

IIRC I pointed out three times that I bought lithiums for cost reasons. But you seemed to have ignored that.

And yes, FLA is apparently very cheap in some places. If I lived there I would have bought them.

But I don't. So I bought what was the most battery for my dollar here in Australia.

[fivecapes]

This 50% reserve business is a red herring. It's not like if you run out of juice you roll to a stop on the interstate shoulder, but I'm sure you never let your diesel tanks fall below half full, 'cos reserve, right?

Running a genny when your FLA hits 50% is the same as for LiFePO4 at 20% whatever the time of day. Cherry picking 2am scenarios is just that, cherry picking, could just as easily have been 2pm for either chemistries.

LiFePO4 discharges to 10-20% because they can. FLA can't (or shouldn't, but feel free to drop it to 20% for daily use if you think it's a myth and just top to "cruising full", your call). Positing the "reserve" argument will not alter the fact that usage patterns will take advantage of or be restricted by that. Usage patterns for the 2 chemistries are and will be different. For certain users the costs are justified whether you care to admit or not. And even if not who are you to judge.

Not everyone wants to muck around with a hygrometer, SOC etc, just as not everyone wants to read by hurricane lamps at night. BTW why are your sails anything but poly tarp, I'm outraged!

Fair winds

[OceanSeaSpray]

Originally Posted by missourisailor

Lack of a real, marine BMS.
Most of the BMS’s are made for land based banks and/or vehicles.
Nordkyn Design ,was at one time, designing a marine specific BMS. But I have not heard from him for quite some time, so even his project seems to be dead.

No, that BMS is on the bench and working, but it needs a bit more attention and the last 2 years have been crazy here.
I will be getting back to it in a week or two with a view of finally getting it over the line. I will need a few people reasonably switched on to give me initial feedback etc. The firmware will be upgradable by end-users so we can add functionality over time etc. That is the bit that still needs some work.

[Simi 60]

Originally Posted by 44'cruisingcat

. So I bought what was the most battery for my dollar here in Australia.

Care to post numbers and suppliers?

Things were a tad rushed with our purchase (boat slipped, bought, new batts, inv and solar and living aboard in 2 weeks) so not a huge amount of research able to be done.
When I found 220ah agm's around the corner on sale and delivered to the boat cheap from bainbridge technologies I jumped on them.
Would be interested to see how the lp4 compared

As a comparison we got 1760ah @ 12v set up as 880ah @ 24v for $3360 delivered.

[hzcruiser]

Originally Posted by fivecapes

This 50% reserve business is a red herring. It's not like if you run out of juice you roll to a stop on the interstate shoulder, but I'm sure you never let your diesel tanks fall below half full, 'cos reserve, right?

Running a genny when your FLA hits 50% is the same as for LiFePO4 at 20% whatever the time of day. Cherry picking 2am scenarios is just that, cherry picking, could just as easily have been 2pm for either chemistries.
[...]

Excellent summary of the last seven pages of this -rambling- discussion.
Let's just agree that it is early days for LFP, some people already have them on board for different reasons, others argue that LFP is still too expensive and more difficult to replace if they break in a far away place.

I believe LA and LFP can actually coexist peacefully even on the same boat!

Outrageous, some might say. Heresy, others will cry and start to pick up a rock, or at least pick up a keyboard to hurl in my direction


It might even be possible that the combination can give you the best of both worlds?
As an intro: What really happens if you connect LFP and LA together?

Not too long ago a gentleman on this forum had a stern warning for us to never, ever directly connect a fully charged batt to an empty batt as the current will be huge and the cables might melt or worse and the batts will get damaged beyond repair! Well I'm proud to say I just topped that and dared to connect an LFP sitting at 13.2V in my lab (not lap) to a dicharged LA batt measuring 12.1V open circuit. And I survived the stunt to tell the story to the world: nothing happened! Nada. Zilch. The Amp meter jumped to 1.5A and is now slowly dropping off. The "bus voltage" dropped to 12.9V. The battery controller is documenting this as we speak, so to speak. Tomorrow I can show the graph of this "disaster waiting to happen", if someone is interested.



Looking at the different voltage thresholds and recommended charge regimes for LA and LFP I can even see signs of a symbiosis here: the LFPs can provide the bulk of the power until they are down to 10 or 20% SOC, then we automatically take them off the bus and the LAs would provide the "reserve" power on those rainy days.



How can that ever work, you might ask? Say we set our charge controllers to simply bulk charge to 14.3V then drop to some float voltage around the LFPs resting voltage (say 13.3V?). Now once our charging source kicks in the LFP will likely absorb more current due to their lower impedance (internal resistance). Charging might continue until the threshold is reached, which means the LFPs are full, the LAs are maybe sitting at 80-90% SOC.

The charge source (if it's one we can control, e.g. alternator, generator, land power) now gets disconnected and the LFPs are topping off the LAs until they're full. LAs at 100% SOC is what we want anyway, right? Brilliant! The LFPs are getting slowly discharged immediately after reaching 100% which is also what's recommended to maximise their life span. Even better!

All the consumers are now driven by the LFPs higher voltage relative to the LAs. If, however, we can't fully charge the LFPs because we rely on wind and solar, nothing bad is going to happen either. The only thing we need to make sure is removing the LFPs from the bus when they're empty, nothing more (unless I missed something crucial here).


Since I don't want to hijack this turf war I might actually start a new thread called...hmm, let me think... "LiFePO4 and FLA a match made in heaven?".

So if anyone would bother to set me straight, please click here.

[44'cruisingcat]

Originally Posted by Simi 60

Care to post numbers and suppliers?

Things were a tad rushed with our purchase (boat slipped, bought, new batts, inv and solar and living aboard in 2 weeks) so not a huge amount of research able to be done.
When I found 220ah agm's around the corner on sale and delivered to the boat cheap from bainbridge technologies I jumped on them.
Would be interested to see how the lp4 compared

As a comparison we got 1760ah @ 12v set up as 880ah @ 24v for $3360 delivered.

It was years ago, so I really don't remember where I DIDN'T buy batteries from.

But I got the lithiums from EV Works in west Aus.

They presently have 100 ah CALB cells for $160 aus.

https://www.evworks.com.au/battery-systems/

But if I had found those batteries at those prices at the time I'd have bought them.

[ramblinrod]

Originally Posted by CatNewBee

You cant be serious...
There is no 50% reserve capacity in a FLA. You can only use maximum 50% of the nominal capacity without causing serious damage. And the many cycles come from 30% discharge, not 50 or 80.

Of course you can abuse your FLA, the dealer around the corner is waiting for you.

Also high current draws kill FLA on the long run. Continous discharge is around 0.1...0.2C.

A FLA battery with 1000Ah can safely continous deliver 100...200A, a a LFP can deliver 1000A. This is a very strong argument for all who use regulary powerfull inverters. The voltage drop of a FLA battery would require much higher capacity to cope with the currents.

Hogwash!

Everyone who has adequate solar and wind can charge their FLA to 100% easily almost every day.

On occasions when they need to, they can dip into their reserve capacity down to 20% and not hurt anything, the same as they would for LifePO4.

I think I've said it about 10 times this thread so far...

Designing with no reserve capacity is BAD DESIGN.

So LifePO4 should be designed for a 90% to 50% charge cycle max.

So if one day the generator doesn't start up...which was my most frequent emergency service call this summer.

How many calls FLA batteries were dead?

1

[hzcruiser]

Originally Posted by 44'cruisingcat

It was years ago, so I really don't remember where I DIDN'T buy batteries from.

But I got the lithiums from EV Works in west Aus.

They presently have 100 ah CALB cells for $160 aus.

https://www.evworks.com.au/battery-systems/

But if I had found those batteries at those prices at the time I'd have bought them.

That's where I got mine from as well. They seem to have the best prices for CALBs (not that there are many LFP resellers in Oz.... maybe I should import a container of CALBs myself...).

[44'cruisingcat]

Originally Posted by ramblinrod

I think I've said it about 10 times this thread so far...

Designing with no reserve capacity is BAD DESIGN.

So LifePO4 should be designed for a 90% to 50% charge cycle max.

Simply repeating something doesn't make it true.

But anyway, what do you mean by reserve capacity? Is it 1 day of power consumption, or 2 days or a week?

Our daily power consumption can vary between less than 100 ah per day, to over 200. Depends on what we're doing. And usually if we're getting plenty of power from the solar, I'll do stuff to use more of it. Like making extra water or using electricity to heat water. If it's cloudy I'll avoid using unnecessary power.

Reality. We replaced 600 ah lead so about 200 ah usable if we want good battery life, with 400 ah lithiums , again 200 usable giving excellent battery life. 10,000 + cycles. That's cool.

[mbartosch]

Originally Posted by ramblinrod

Hogwash!



Everyone who has adequate solar and wind can charge their FLA to 100% easily almost every day.



On occasions when they need to, they can dip into their reserve capacity down to 20% and not hurt anything, the same as they would for LifePO4.



I think I've said it about 10 times this thread so far...



Designing with no reserve capacity is BAD DESIGN.



So LifePO4 should be designed for a 90% to 50% charge cycle max.

Hogwash. Nice word.

Anyway, real world numbers from our 33 day ocean crossing:

Started with 100% SoC, arrived with 45% SoC
400 Ah LiFePO4 @12V
435 Wp Solar
120 A Alternator
No wind gen, NO other charging sources.
Total engine hours on crossing (checked the log book): 52 (1.53 h per day).
SoC policy: start the night at no less than 45% SoC, when running the engine to recharge go to 65-70% to leave room for solar input during the day.
I can show log book pages with logged SoC ranging from 22% to typically 75% if anyone doubts the numbers.
Our consumption at anchor: 100-120 Ah, on the move: 250-300 Ah
Can you do this with LA? Really?

[newhaul]

Originally Posted by ramblinrod

Hogwash!

Everyone who has adequate solar and wind can charge their FLA to 100% easily almost every day.

On occasions when they need to, they can dip into their reserve capacity down to 20% and not hurt anything, the same as they would for LifePO4.

I think I've said it about 10 times this thread so far...

Designing with no reserve capacity is BAD DESIGN.

So LifePO4 should be designed for a 90% to 50% charge cycle max.

So if one day the generator doesn't start up...which was my most frequent emergency service call this summer.

How many calls FLA batteries were dead?

1

why the generator answer again
What I have gleaned so far is each his own.
Fla specific size constraints . Lifepo4 can be designed to just about any footprint.
For my small cruiser the weight difference is important.
Trojan t105 28kg x2 =56kg for 225ah capacity .
My Lfp 200ah at 20kg And more usable capacity.
26kg difference for a 29 ft cruiser that's huge.

[john61ct]

Many if not most boats can only very rarely get their lead bank back to 100% Full from solar. Just not enough space for the panels required.

Running the genny in the morning will help on sunny days.

The chemistry of the bank is irrelevant to the basic equation,

You must put back in 100+% of what you take out.

LFP's great advantage is, no need to worry about getting to Full.

Also accepting full amps output all the way up the SoC curve, no resistance-trailing amps phenomenon.

And lighter weight.

But in RR's market, the price difference is IHO not worth those advantages.

His rig, his choice.

For those where the price difference is much lower, the scales tip the other way more often.

It is stupid to get all personally tied up in thinking there is one right answer for everyone,

in either side of the argument.

It depends, your rig, your choice.

[daletournier]

I was just reading the below, does DOD effect life cycles of Lifepo4 as written below? I thought DOD didn't effect longevity in regards to Lifepo4?

Also what determines the big difference in life cycles between Calbs and Winston?


CALB

400AH - 3000 cycles @ 70% DOD, 2000 cycles @ 80% DOD
Max constant discharge current - 2C
Max constant charge current - 1C
SOC usage window - 10-90% SOC
Price:- $480us


Winston*

400ah - 7000 @ 70% DOD, 5000 @ 80% DOD
Max constant discharge current - 3C
Max constant charge current - 3C (not sure if this is constant or impulse? Not clear on website)
SOC usage window - not specified.*

[john61ct]

Originally Posted by daletournier

I was just reading the below, does DOD effect life cycles of Lifepo4 as written below? I thought DOD didn't effect longevity in regards to Lifepo4?

Yes the curve is similar to lead.

But the #cycles is so high anyway, as well as the investment cost / AH, most people just go for sizing based on 80%.

Better to build in some reserve for solar-only anyway, so if you average shallower you'll get many more thousand cycles.

> Also what determines the big difference in life cycles between Calbs and Winston?

Lifetime does not vary that much between top brands.

Such stats cannot be used as real, for comparisons between makers, only within one brand.

Marketing vs Engineering departments vary in their influence.

[a64pilot]

Originally Posted by daletournier

I was just reading the below, does DOD effect life cycles of Lifepo4 as written below? I thought DOD didn't effect longevity in regards to Lifepo4?

Also what determines the big difference in life cycles between Calbs and Winston?


CALB

400AH - 3000 cycles @ 70% DOD, 2000 cycles @ 80% DOD
Max constant discharge current - 2C
Max constant charge current - 1C
SOC usage window - 10-90% SOC
Price:- $480us


Winston*

400ah - 7000 @ 70% DOD, 5000 @ 80% DOD
Max constant discharge current - 3C
Max constant charge current - 3C (not sure if this is constant or impulse? Not clear on website)
SOC usage window - not specified.*

I think what would be educational is to find out what the electric car manufacturers do SOC wise, that would likely tell you what is best for your battery bank, how deep to discharge and how high to charge.
I know our Prius won’t charge higher than 80% SOC nor discharge less than 40% SOC, leaving of course only 40% of bank capacity usable.
Now a Prius isn’t an electric car, it’s bank is discharged and charged many, many times, so it’s not likely a model to follow.
But find out what Nissan, Chevrolet, Tesla, BWW, VW etc.
do, I’d bet they are all pretty close to each other, surely they have done testing on SOC vs life span.

My gut feeling is that we will find that there isn’t all that much more usable SOC than lead, if your trying to maximize lifespan, or push it way out anyway.
It would also be interesting as to how they die, is it often a sudden death or do they go slowly, diminishing capacity over a long time?

Design life limit on the Prius pack is 250,000 miles or ten years