LiFePO4 vs FLA - The Real Deal

[thinwater]

Originally Posted by newhaul

...
26kg difference for a 29 ft cruiser that's huge.

Please put a dollar value on 26kg. I'm guessing the boat at about $5/pound based on purchase price, and the value is probably about 1/2 that in the bilge, since it does not affect motion. $115 for carrying 26 kg more weight. I think people could buy that. So I don't see how that is worth more than $3/pound for a 10 years investment, or may be $1.50/pound over the life expectancy of the boat. $86 for carrying 26 kg more weight. I think people could buy that.


So you saved $86. That doesn't even figure in the math for a cruiser. A racer or a performance multi will have different math. Just sayin'. Unless you have a different way of valuing weight, which would be interesting to me. But "huge" is not a number.

[newhaul]

Originally Posted by thinwater

Please put a dollar value on 26kg. I'm guessing the boat at about $5/pound based on purchase price, and the value is probably about 1/2 that in the bilge, since it does not affect motion. $115 for carrying 26 kg more weight. I think people could buy that. So I don't see how that is worth more than $3/pound for a 10 years investment, or may be $1.50/pound over the life expectancy of the boat. $86 for carrying 26 kg more weight. I think people could buy that.


So you saved $86. That doesn't even figure in the math for a cruiser. A racer or a performance multi will have different math. Just sayin'. Unless you have a different way of valuing weight, which would be interesting to me. But "huge" is not a number.

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.

[OceanSeaSpray]

Originally Posted by ramblinrod

Everyone keeps saying they only need half the LifePO4 capacity, but as I have stated, this simply isn't true.

You are stating plenty out of no experience.

It has nothing to do with reserve capacity, but cycle life. If you cycle FLAs down to 50% (bad idea) in a real-world scenario off-grid where they often won't get recharged to full for a while, you throw them out within 2-3 years and the end is miserable with a bank that won't take charge and chronic low voltage. The so-called "reserve" capacity is only there to try and extend the life of the battery. It is dead lead.
These are the good old batteries we throw out and the payback period for lithium is not long.

People who manage to get 6 years and over out of FLAs keep them close to full most of the time with a bank that is disproportionally large and shallow cycling. It is very heavy and rather expensive and it still doesn't charge efficiently. In these situations, we have replaced over 600Ah of FLAs with 200Ah of lithium only and it solved all issues.

Lithiums can be left at any low state of charge for any amount of time (0% SOC being 2.5V/cell by definition) without compromising their life, so they last. Furthermore, they recharge much more efficiently and can absorb all of the available energy at any time until almost full, and this makes a huge difference in practice. They are far superior at taking advantage of opportunistic recharging.

This is why only half of the capacity is needed in practice and I use virtually all the capacity of the battery at times, >95%, because I would rather wait for a sunny day and keep drawing it down rather than doing something as stupid as starting the engine when I don't absolutely have to.
Most of the time, I only use a fraction of the capacity and the system has plenty of reserve to pull through some rainy days, because I can draw on it all the way down to <5% SOC if needed. This happens a few times each year in winter.

This being said, it makes no sense to install lithium batteries unless you basically live on board all the time. If the battery is not going to be cycling and only sees occasional use followed by a full recharge, FLA lasts fine and it is cheap and simple.
Yet I do hear from people who want to build lithium systems "for no reason", other than boredom or chronic excess of capital maybe. I don't know what happens next, because they usually walk away when I point out that it is stupid. It is replacing a working solution with a whole new problem: trying not the charge the battery because it is not being used.

[44'cruisingcat]

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?

Just as with lead, shallower cycles allow more cycles. It's just that really deep cycling doesn't result in very short lifespans like it does with lead.

There are graphs on the internet. What they show, is that a well sized LiFePO4 batery bank could quite well be the last set of batteries you'd ever need to buy.

BTW, I'm trying to make sure there's no hint of "agression " in my posts. Please let me know whether or not I'm succeeding.

[newhaul]

Ok if you are cycling your batteries every day
Fla trojan t105's expected lifecycles 1000
1000÷365 = 2.75years. ( daily cycling down 80% DOD)
from Solar Ray: Deep Cycle Batteries
it seems that if you only DOD to 30% it will double the life to about 2000 cycles. OR About 5.5 years.

From the renogy paper I posted

4000 cycles at 80% DOD x 365 = 11 years that's with full time daily 8o% DOD.
But a DOD of only 30% seems to give a possible life of over 35 years.

This makes the decision for me almost a no brainer
4x life . At 80% DOD and well over 6 times at 30%DOD.

[john61ct]

Originally Posted by newhaul

Ok if you are cycling your batteries every day
Fla trojan t105's expected lifecycles 1000
1000÷365 = 2.75years. ( daily cycling down 80% DOD)

no way IRL at 80% discharge, even EoL going below 70% SoH

Don't think they claim that even in the lab.

> 4000 cycles at 80% DOD x 365 = 11 years that's with full time daily 8o% DOD.

With "avoid the shoulders" charging, you should get lots more than that, barring unforeseen. . .

From good quality prismatics, no idea whose is inside the Renogy's best to avoid drop-ins for this discussion.

[OceanSeaSpray]

Originally Posted by 44'cruisingcat

Just as with lead, shallower cycles allow more cycles. It's just that really deep cycling doesn't result in very short lifespans like it does with lead.

The data supporting this is obtained from aggressive cycling cells at high C-rates, because when they want data for 3000 cycles, they don't want this to take years. Well, WE don't mind. Once the voltage sags too much at 80% of nominal capacity, they call the cells gone. This is completely meaningless for us. We could take their spent cells and run on them for years after that because of the low C-rates.

There is nothing supporting the idea that deep cycling LFP in itself reduces battery life, but there is data supporting that degradation is in fact related to 1/ time and 2/ the amount of charge that the cells has exchanged, at least for some Li-ion chemistries. There is also data supporting a reduction in capacity and increase in internal resistance when cells spend a lot of time at high SOC: shallow cycles = more time at high SOC.

So I cycle slowly, deep whenever needed and I recharge fully only once the battery has discharged enough: less time at high SOC and less full recharge cycles. But when I do recharge, I do it properly.

[newhaul]

Originally Posted by john61ct

no way IRL at 80% discharge, even EoL going below 70% SoH

Don't think they claim that even in the lab.

> 4000 cycles at 80% DOD x 365 = 11 years that's with full time daily 8o% DOD.

With "avoid the shoulders" charging, you should get lots more than that, barring unforeseen. . .

From good quality prismatics, no idea whose is inside the Renogy's best to avoid drop-ins for this discussion.

the renogy units are only brought up due to specific data in their Pdf.
Which states they are built up with 26650 cells.
And their data suggests a 13,000 life cycle with a 30% DOD on their battery.
So definitely last battery bank I would ever need .

[john61ct]

Maybe if you're 80. . .

Mfg cycle claims based on their lab tests are completely useless for comparing to other mfg, only for comparing lines from the same brand.

And certainly nothing to do with real life.

There are only a handful of known-good LFP manufacturers. Same is true with FLA, or AGM, difference is LFP is a global market, only distribution/pricing is different, not the mfg.

I'm not saying the Renogy are" known bad", we won't find out until dozens of testers report back after 6-10 years.

But for that kind of money, DIY I'd want Winston/Voltronix, CALB, GBS, A123 or Sinopoly.

Unless putting in a system from OceanPlanet (Lithionics), Victron or MasterVolt.

If I've left any out, please let me know.

In this case you can't even find out who makes their cells. Likely so they can change suppliers anytime.

[newhaul]

Originally Posted by john61ct

Maybe if you're 80. . .

Mfg cycle claims based on their lab tests are completely useless for comparing to other mfg, only for comparing lines from the same brand.

And certainly nothing to do with real life.

There are only a handful of known-good LFP manufacturers. Same is true with FLA, or AGM, difference is LFP is a global market, only distribution/pricing is different, not the mfg.

I'm not saying the Renogy are" known bad", we won't find out until dozens of testers report back after 6-10 years.

But for that kind of money, DIY I'd want Winston/Voltronix, CALB, GBS, A123 or Sinopoly.

Unless putting in a system from OceanPlanet (Lithionics), Victron or MasterVolt.

If I've left any out, please let me know.

In this case you can't even find out who makes their cells. Likely so they can change suppliers anytime.

not quite there yet but close. And fast approaching.

[fivecapes]

Originally Posted by a64pilot

See, the biggest huge selling point of one EV over the other is range, so it has to be extremely tempting to drive the SOC a little deeper so you can advertise a greater range than the other guy.
My point is that I doubt they are leaving SOC unused, the marketing dept has to be driving the Engineering dept hard to advertise a greater range.

Well, the 3 series still keeps the old school manual handbrake in the centre console unlike most other manufacturers, much to the chagrin of new buyers looking at it. It's a design choice that might appear counter intuitive much like the DOD on the 330e. It's telling that 3 series afficionadoes don't complain about it. Maybe it's because you need it to drift a corner at 100kmh, I don't know. Point is you can't conclude the reasons between the choices of DOD without deeper examination, but I can see why someone might make that cursory conclusion, rightly or wrongly.

[ramblinrod]

Originally Posted by OceanSeaSpray

You are stating plenty out of no experience.

It has nothing to do with reserve capacity, but cycle life. If you cycle FLAs down to 50% (bad idea) in a real-world scenario off-grid where they often won't get recharged to full for a while, you throw them out within 2-3 years and the end is miserable with a bank that won't take charge and chronic low voltage. The so-called "reserve" capacity is only there to try and extend the life of the battery. It is dead lead.
These are the good old batteries we throw out and the payback period for lithium is not long.

People who manage to get 6 years and over out of FLAs keep them close to full most of the time with a bank that is disproportionally large and shallow cycling. It is very heavy and rather expensive and it still doesn't charge efficiently. In these situations, we have replaced over 600Ah of FLAs with 200Ah of lithium only and it solved all issues.

Lithiums can be left at any low state of charge for any amount of time (0% SOC being 2.5V/cell by definition) without compromising their life, so they last. Furthermore, they recharge much more efficiently and can absorb all of the available energy at any time until almost full, and this makes a huge difference in practice. They are far superior at taking advantage of opportunistic recharging.

This is why only half of the capacity is needed in practice and I use virtually all the capacity of the battery at times, >95%, because I would rather wait for a sunny day and keep drawing it down rather than doing something as stupid as starting the engine when I don't absolutely have to.
Most of the time, I only use a fraction of the capacity and the system has plenty of reserve to pull through some rainy days, because I can draw on it all the way down to <5% SOC if needed. This happens a few times each year in winter.

This being said, it makes no sense to install lithium batteries unless you basically live on board all the time. If the battery is not going to be cycling and only sees occasional use followed by a full recharge, FLA lasts fine and it is cheap and simple.
Yet I do hear from people who want to build lithium systems "for no reason", other than boredom or chronic excess of capital maybe. I don't know what happens next, because they usually walk away when I point out that it is stupid. It is replacing a working solution with a whole new problem: trying not the charge the battery because it is not being used.

Thank you for your contribution.

The reason FLA has received a bad rap, and some claim way too early demise, is due to their own dang fault; chronic undercharging, and leaving repeatedly at a low SOC for lengthy periods.

One has to put back in what they take out (plus a little), every day (almost) else the batteries (any technology) will be chronically undercharged.

For a full time cruiser, I recommend that first an energy analysis be performed to determine average daily consumption, at anchor and when underway.

Then, for every 100 A-hr of daily consumption, install:

- 200 A-hr of cheap FLA battery
- 200 W solar
- 200 W wind
- 40 A alternator

With this set up, you will have ample power.

Your FLA batteries will last about 5 years.

For places with generally sunny and breezy climates, (e.g. Caribbean), typically, you will only require alternator operation 2 days out of 7 for an hour in the morning, (one of those days may require an additional hour in the evening).

With these ratios, if the alternator is used when the bank is low (50% or less on rare occasions, when their is insufficient wind and solar) the bank will take close to 100% of it's output for about an hour. When the bank is up to 75 to 80%, stop the alternator and let wind and solar bring it up the rest of the way.

If you do not design your LiFePO4 system with reserve capacity, (A-hr rating twice average daily consumption), you may run out of power on days when load exceeds average or you screw up and fail to meet charging needs.

When the BMS shuts the batteries down, you will not be able to even light an LED anchor light.

Whereas with FLA, because you automatically design ample reserve, to avoid going below 50% too often, if you go over the daily a bit, even 30%, no harm no foul, everything is still running, just charge it back up. Pour in the alternator till 80% and let wind and solar due the rest.

It really is this easy.

[ramblinrod]

Originally Posted by ramblinrod

Thank you for your contribution.

The reason FLA has received a bad rap, and some claim way too early demise, is due to their own dang fault; chronic undercharging, and leaving repeatedly at a low SOC for lengthy periods.

One has to put back in what they take out (plus a little), every day (almost) else the batteries (any technology) will be chronically undercharged.

For a full time cruiser, I recommend that first an energy analysis be performed to determine average daily consumption, at anchor and when underway.

Then, for every 100 A-hr of daily consumption, install:

- 200 A-hr of cheap FLA battery
- 200 W solar
- 200 W wind
- 40 A alternator

With this set up, you will have ample power.

Your FLA batteries will last about 5 years.

For places with generally sunny and breezy climates, (e.g. Caribbean), typically, you will only require alternator operation 2 days out of 7 for an hour in the morning, (one of those days may require an additional hour in the evening).

With these ratios, if the alternator is used when the bank is low (50% or less on rare occasions, when their is insufficient wind and solar) the bank will take close to 100% of it's output for about an hour. When the bank is up to 75 to 80%, stop the alternator and let wind and solar bring it up the rest of the way.

If you do not design your LiFePO4 system with reserve capacity, (A-hr rating twice average daily consumption), you may run out of power on days when load exceeds average or you screw up and fail to meet charging needs.

When the BMS shuts the batteries down, you will not be able to even light an LED anchor light.

Whereas with FLA, because you automatically design ample reserve, to avoid going below 50% too often, if you go over the daily a bit, even 30%, no harm no foul, everything is still running, just charge it back up. Pour in the alternator till 80% and let wind and solar due the rest.

It really is this easy.

PS, people change their boats every 5 years (on average), so if you are looking at a payback because you think your LifePO4 battery will last 33 years (BS), you will be sorely disappointed, when the new owner takes your boat with those expensive batteries for a few pennies on every dollar you paid.

[newhaul]

Originally Posted by ramblinrod

Thank you for your contribution.

The reason FLA has received a bad rap, and some claim way too early demise, is due to their own dang fault; chronic undercharging, and leaving repeatedly at a low SOC for lengthy periods.

One has to put back in what they take out (plus a little), every day (almost) else the batteries will be chronically undercharged.

For a full time cruiser, I recommend that first an energy analysis be performed to determine average daily consumption, at anchor and when underway.

Then, for every 100 A-hr of daily consumption, install:

- 200 A-hr of cheap FLA battery
- 200 W solar
- 200 W wind
- 40 A alternator

With this set up, you will have ample power.

Your FLA batteries will last about 5 years.

For places with generally sunny and breezy climates, (e.g. Caribbean), typically, you will only require alternator operation 2 days out of 7 for an hour in the morning, (one of those days may require an additional hour in the evening).

With these ratios, if the alternator is used when the bank is low (50% or less on rare occasions) the bank will take close to 100% of it's output for about an hour. When the bank is up to 75 to 80%, stop the alternator and let wind and solar bring it up the rest of the way.

If you do not design your LiFePO4 system with reserve capacity, (A-hr rating twice average daily consumption), you may run out of power on days when load exceeds average or you screw up and fail to meet charging needs.

When the BMS shuts the batteries down, you will not be able to even light an LED anchor light.

Whereas with FLA, because you automatically design ample reserve, to avoid going below 50% too often, if you go over the daily a bit, even 30%, no harm no foul, everything is still running, just charge it back up. Pour in the alternator till 80% and let wind and solar due the rest.

It really is this easy.

is there actually a reason you keep pushing Fla over Lfp
No one system works for every cruiser or even the same boat for different cruisers.
With 400 watts solar and 400 wind ( the smallest marine grade I have seen ) you will not go dead with a properly sized bank regardless of chemical makeup. Btw even with Lfp it is still my recommendation to have a Fla start battery. Lfp dead start your engine and charge them back up . What's the problem.
I'm still getting 4x life over Fla banks.

[newhaul]

Originally Posted by ramblinrod

PS, people change their boats every 5 years (on average), so if you are looking at a payback because you think your LifePO4 battery will last 33 years (BS), you will be sorely disappointed, when the new owner takes your boat with those expensive batteries for a few pennies on every dollar you paid.

where do you get the part about everyone changing boats every 5 years.
Most of my customers have had the same cruising vessel for over 20 years.
Most of my cruising friends intend on keeping their boats for well over 10 years above the 10 they have owned them.