Cost of LiFePo4 vs Lead in Your Market

[Dockhead]

This is how it boils down here:





I would have liked to include Firefly Oasis in the comparison but we can't seem to get them in the UK.


This comparison considers usable capacity -- 50% for lead, and 80% for lithium -- but not cycle life.


This comparison considers only the consumable element of the battery system -- the lead batts or the lithium cells. Switching a boat from lead to lithium requires a capital expense for conversion including BMS system, contactors, and possibly changes to wiring or charging systems. The total conversion cost will vary greatly depending on the boat, but on mine will be about £1200, about the cost of one set of Trojans.



This comparison led me to the conclusion that in the UK, lithium is actually quite a bit cheaper than lead. It's far cheaper than quality AGM batteries even without considering cycle life. It's less than twice the price of Trojan T-105s for a cycle life which must be at least triple, and much more than triple in partial SOC duty, but with the caveat that lithium degrades quickly as a function of time so lithium not used constantly won't produce as many cycles.



It will be interesting to hear what this looks like in other markets.

[djmarchand]

If you assume that $ and Pounds are at par, then your data pretty well matches US values.

You say that Li has three times the cycle life as FLAs. FLA life is well known in marine applications. Li is just a guess and I wouldn't put a lot of faith in it until more history is available. Also 1,200 Pounds is a lot to support Li.

Therefore, stick with FLAs would be my approach..

David

[thinwater]

Originally Posted by Dockhead

... but with the caveat that lithium degrades quickly as a function of time so lithium not used constantly won't produce as many cycles....

Please explain. My understanding is the wet life of Li and Pb are similar, and that the differences are in cycle behavior. I have not heard that Li degrades quickly unless misused.

[john61ct]

Calendar life takes over as a bank rarely cycles.

We don't yet know.

Temperature makes a **huge** difference.

[a64pilot]

Not even close to US prices.
You can get lead for $2 a useable AH
Maine Sails number was what $8.44 an AH?
In particular the Lifeline number is Wacko.

I disagree with your consumable only number.
It's like saying a boom furling system is not more expensive to change to, cause you only buy the boom once.

The relevant number is how big a check do I have to write for X.
Another example, my Titanium chainplates cost less than half as much as SS, cause I'll never have to replace them.


Now at the prices you quoted, only a fool would buy Lifeline, and Id have an LFP bank

However, You can't justify them on price, not in the US anyway.
You have other use another metric.

[john61ct]

Cycle life is minimum 8-10 times longer.

Properly coddled can easily be 20, as in decades of daily use.

As long as a "critical event" does not occur.

[newhaul]

Originally Posted by john61ct

Cycle life is minimum 8-10 times longer.

Properly coddled can easily be 20, as in decades of daily use.

As long as a "critical event" does not occur.

proper coddling is easier and less labor intensive with Lfp .


easier to prevent critical error issue with Lfp than with Fla. Fla critical issue is PSOC
Lfp is don't over charge and don't allow to go dead flat. ( which btw is a killer of both.)

[Singularity]

I bought 400ah LFP a few months ago for $2000. If I would have accepted the usable Ah that the previous lead gave, I could have just bought $1000k worth of LFP. What does 400ah lead cost now in the US?

For the life of me, LFP is so inexpensive now that I can see no justification for buying lead again. If the doc says it's okay to buy green bananas, then go ahead with LFP. LFP and a good inverter immediately antiquates lead, and some DC boat systems (e.g. DC refrigeration). Don't get confused with AC/DC, just start thinking AC to power everything with solar or a cheap DC diesel to top off the LFP.

It's really a new paradigm that many don't seem to grasp. I didn't fully appreciate it until last week staring at my larger AC genny. I had lusted for that thing; now I see it as a highly reliable overweight relic of a previous era taking up too much space in my engine room.

LFP is the only way to go. The old dog has to learn a couple new tricks, but is forever rewarded by the continued treats that the new skills afford.

[Kelkara]

Your value for Lifelines is a factor of 2 out:

690 x 2 / 105 = 13.14

[Dockhead]

Originally Posted by thinwater

Please explain. My understanding is the wet life of Li and Pb are similar, and that the differences are in cycle behavior. I have not heard that Li degrades quickly unless misused.

My understanding -- which could be wrong; I don't claim to be an expert -- is that lithium has a shelf life of 10 years, and loses something like 4% of its capacity every year just from the passage of time.

[Dockhead]

Originally Posted by Kelkara

Your value for Lifelines is a factor of 2 out:

690 x 2 / 105 = 13.14

No, it's all amp hours AT 24V.


You can divide the per amp hour costs of ALL of the batteries by 2, if you want 12 volts.


This is the analysis I did for my own boat, which is 24v.

[Dockhead]

Originally Posted by a64pilot

Not even close to US prices.
You can get lead for $2 a useable AH
Maine Sails number was what $8.44 an AH?
In particular the Lifeline number is Wacko.

I disagree with your consumable only number.
It's like saying a boom furling system is not more expensive to change to, cause you only buy the boom once.

The relevant number is how big a check do I have to write for X.
Another example, my Titanium chainplates cost less than half as much as SS, cause I'll never have to replace them.


Now at the prices you quoted, only a fool would buy Lifeline, and Id have an LFP bank

However, You can't justify them on price, not in the US anyway.
You have other use another metric.

Well, putting my financier hat on -- it is correct to separate running costs from capital costs.


The approach is correct -- compare first the cost of the consumables.


THEN see if the difference is worth investing the cost of converting.


I never suggested ignoring the cost of converting -- but it should not be lumped in with the cost of the consumables.


This is especially relevant in case of a new build where there is no lead infrastructure to throw away -- you start with a clean sheet of paper.

[Maine Sail]

Originally Posted by john61ct

Calendar life takes over as a bank rarely cycles.

We don't yet know.

Temperature makes a **huge** difference.

Heat is a major contributor to calendar life as is continuing charging after the battery is full, floating etc....



Because our waters are cold, rare to see our battery above 75F, and my storage temps are also cool/cold, & I never let them sit anywhere near 100% SOC, nor do I float them, or charge below freezing, I've seen virtually no effects of calendar aging on our 2009 400Ah Winston cells.



This is with cells at nearly 1100 cycles to 80% DOD and they are still delivering in excess of 400Ah when I capacity test them.

[Maine Sail]

Originally Posted by Dockhead

My understanding -- which could be wrong; I don't claim to be an expert -- is that lithium has a shelf life of 10 years, and loses something like 4% of its capacity every year just from the passage of time.

Again, my cells were manufactured in 2009 and they still deliver in excess of their 400Ah rating at 1100 cycles and 9 years of age.. If they all of a sudden fall off a 10 year cliff I will let you know......

[Jerry Woodward]

Originally Posted by Singularity

I bought 400ah LFP a few months ago for $2000. If I would have accepted the usable Ah that the previous lead gave, I could have just bought $1000k worth of LFP. What does 400ah lead cost now in the US?

For the life of me, LFP is so inexpensive now that I can see no justification for buying lead again. If the doc says it's okay to buy green bananas, then go ahead with LFP. LFP and a good inverter immediately antiquates lead, and some DC boat systems (e.g. DC refrigeration). Don't get confused with AC/DC, just start thinking AC to power everything with solar or a cheap DC diesel to top off the LFP.

It's really a new paradigm that many don't seem to grasp. I didn't fully appreciate it until last week staring at my larger AC genny. I had lusted for that thing; now I see it as a highly reliable overweight relic of a previous era taking up too much space in my engine room.

LFP is the only way to go. The old dog has to learn a couple new tricks, but is forever rewarded by the continued treats that the new skills afford.

Can you please tell me where I can get 400 ah of LFP for $2,000? Does this include the BMS? What about quality? My research indicates it will run more like $5,000 for a 400ah system.