Realistic non-bs comparison of lithium to lead

[CatNewBee]

The LFP bank was for us the best investment in electric stuff ever. In the very unlikely circumstance they fail in the future at some point, I would buy them again.

They are not more expensive than the firefly or the lifeline at all. A 1000Ah cell costs 1200€ inclusive 20% tax, so 1200$ without sales tax. They are overprovisioned regarding power output, 4 cells build a 13.4V Battery with 16kWh usable energy (tested myself, from full charge at 3.65V per cell down to 2.9V/cell they yeld 1200Ah continous discharge with 200A using 2 x 1300W blower / heater and measured with Victron BMV and a Wattmeter on the 220V side after the inverter), with a weight of 160kg only (320lb). With the BMS, wiring and solenoids you will end up with 6000$, very close to the Firefly's.

BUT the lfp have almost no voltage drop, can be charged or discharged continously at 1C, 1000A! and can yeld or accept up to 3C short time, that said, they swallow any solar or whatever power seamlessly and efficiently, dont get even warm doing so, perfect for heawy loads like propulsion, A/C, galley appliances etc.

They are like shore power on board. No voltage drop whatsoever, regardless what loads you turn on.

With the right charge electronics you could completely recharge them from empty to full within 1 hour.

They are really amazing, no FLA even comes close to them.

[john61ct]

A packaged Victron system is *a lot* more than double the most expensive lead bank.

Even taking greater usable AH into account, say 5-7x more expensive, at least in the NA market

So there is no way to justify them from a purelt economic POV, unless the weight issue makes them necessary.

A lead bank lasting say 8 years is normal if given the same level of care infrastructure and attention you'd give LFP.

So ROI payback based on greater longevity is a 35+ year period. Entirely possible IMO, but not a formula that would make sense to an objective financial adviser.

That said, we are not rational actors, and I still buy LFP, just because I want to, and am willing to spend the extra money.

[KTP]

I kind of agree here with John61ct. I am not seeing any packaged system of LiFePO4 with safety devices that is anywhere close to the price of Firefly or Lifeline.

Also, the FireFly and Lifeline have a warranty which is actually usable. The best I have heard about DIY LiFePO4 is perhaps a 1 year warranty but you are responsible for shipping charges. If you buy direct from China, forget about any warranty at all.

As I said, right now Torqeedo is really the only one I would consider for a off the shelf lithium battery (it isn't LiFePO4 though). They have a 2 year warranty I believe. About $20k for a system that is the same capacity as a $8k firefly bank, but much lighter and waterproof.

[CatNewBee]

I would not buy a pre-packaged Victron system, no matter if LFP or AGM.

You compare apples with oranges.

You buy single cells FLA, so compare them to single cells LFP.

... And the Torquedo is out of bond.... If you starting that way, than calculate the bank with NiMh electric drill battery packs. [emoji12]

The Winston prismatic cells are very competitive price wise, there is a large scale of sizes between 60Ah to 10000Ah to chose from, and the Ah price is almost linear along the capacity range, so you can build your dream battery of any size that meets your needs.

[john61ct]

Originally Posted by KTP

Torqeedo is really the only one I would consider for a off the shelf lithium battery (it isn't LiFePO4 though).

Then IMO not suitable for inside a living space on a boat.

And will have a very small fraction of the cycle lifespan.

[john61ct]

Originally Posted by CatNewBee

The Winston prismatic cells are very competitive price wise, there is a large scale of sizes between 60Ah to 10000Ah to chose from

But most boaters do not have your DIY engineering skillset.

And please identify a reliable supplier of those bare cells, ideally with US warranty support.

[CatNewBee]

Originally Posted by john61ct

But most boaters do not have your DIY engineering skillset.

And please identify a reliable supplier of those bare cells, ideally with US warranty support.

Unfortunately I am not a US citizen, I am in the EU.
There are 3 supplier / importer with EU warranty around, some ship abroad. There are also system integrators, that could do it for you too and will sell you a battery ready to use with a BMS if you are not able / willing to connect some wires yourself. Also all necessary parts are available.

But you neeed also some skills to connect 12 AGM batteries propperly together without running into the risk of an explosion if eventually one cell gets a shortcut during her life cycle.

You are playing around with the same energy amount, it is as dangerous with any type of storage regardless if AGM, FLA or LFP, it isn't a game.

[KTP]

Originally Posted by john61ct

Then IMO not suitable for inside a living space on a boat.

And will have a very small fraction of the cycle lifespan.

No, the Torqeedo is actually safer than these LiFePO4 packs. It uses Japanese LiMNC cells, each with a safety fuse, then the whole pack is protected against overcharge, overdischarge, water intrustion, short circuit. I would put one under my pillow if they were softer.

[CatNewBee]

Originally Posted by KTP

No, the Torqeedo is actually safer than these LiFePO4 packs. It uses Japanese LiMNC cells, each with a safety fuse, then the whole pack is protected against overcharge, overdischarge, water intrustion, short circuit. I would put one under my pillow if they were softer.

This is where they belong.

Why not using smartphone batteries, lets say from Apple. Some people sleep with their iPhone on the ear... And it is an american company, and you can charge them wirelessly in the mean time [emoji12][emoji15]

[daletournier]

Something of late I've noticed is more "non educated" cruisers have lifepo or are talking about getting them. I don't mean this as an insult to anyone.

There's a number of contributors here that I consider very knowledgeable, the users of lifepo I'm coming across are much less knowledgeable than I, and I certainly don't compare myself to some here YET these guys are getting by just fine.

Just an observation.

[john61ct]

Originally Posted by CatNewBee

Unfortunately I am not a US citizen, I am in the EU.

And that is my point.

Relative price points and the quality of the supply chain varies enormously by market.

The fact that high quality true deep cycling lead banks can be picked up locally for $1 / AH @12V is a wonderful thing in the US.

However a quality LFP system from a reliable supplier is very hard to find, and $10 / AH would be cheap.

So the LFP market here will develop much more slowly.

[DotDun]

Originally Posted by john61ct

And that is my point.

Relative price points and the quality of the supply chain varies enormously by market.

The fact that high quality true deep cycling lead banks can be picked up locally for $1 / AH @12V is a wonderful thing in the US.

However a quality LFP system from a reliable supplier is very hard to find, and $10 / AH would be cheap.

So the LFP market here will develop much more slowly.

Exactly!

I just bought (6) T-105s, 675AH, for $604 out the door! 400AH of LFP would be minimum 5 times, most likely 6 times the price, even ordered from the EU. My last set of T-105s lasted 7 years. With 825W of solar, I can't imagine how LFP would improve my life style enough to justify the $2500-$3000 up-charge!

[44'cruisingcat]

Originally Posted by KTP

I am trying to decide between lithium batteries and lead acid batteries to power an electric drive in our 34 foot Pacific Seacraft sailboat. We have removed a 450 pound diesel engine + transmission, sea water strainer, Racor filter, exhaust riser, 70 pound diesel tank and 210 pounds of diesel fuel. Thus we have about 730 pounds to work with before exceeding the previous displacement of our craft. The new electric brushless motor plus control and reduction/mount will be less than 50 pounds, leaving about 680 pounds for batteries and wire.

I am inclined to start with eight Lifeline 12V AGM in 125AH capacity in a group 31 case. These will fit nicely in the port and starboard storage under the seats in the main cabin which is fairly low and balanced. At 74 pounds each, this would be 592 pounds, or about 90 pounds less than the old engine and fuel. At 48V nominal and 250AH, draining the batteries 50% at a 8 hour rate would yield 5,760Wh with a lab environment lifetime of 1000 cycles according to Lifeline data. Draining to 80% at the same 8 hour rate would yield 9,216Wh with a lab environment lifetime of approximately 500 cycles.

For initial use to enter and leave crowded marina and motor down channels to sailing waters, the 8 hour rate should be realistic and the batteries will be charged back to full after each cycle or within a day or two. Our plan also has quite a bit of solar spread around the boat, hopefully yielding 400 to 800 watts during peak sun from approximately 1600 watts of panels (assuming a lot of shading will prevent the system from ever really achieving the full rated output). Thus a day at anchor might yield something like 2kWh up to 6kWh back into the battery bank. There is also some potential for sailing regen with the electric motor/prop in strong winds but this will have to be tested and is not really expected to contribute much.

Eventually I would like to have a better battery solution than the AGM but I do not think we are quite there yet (it always seems a few years out, like landing on Mars). Companies have come and gone, BMS devices discontinued, very few tried and true off the shelf products that can be trusted to perform for years. Probably Torqeedo is the closest match with their 26V 2700 Wh waterproof, multiple protected packs for ~$2500 but these require individual chargers, special key switches, etc. They also claim only 900 cycles at 80% DoD and the batteries lose 4% a year capacity to age. At 80% DoD and a 8 hour rate, they would have likely double or better the lifetime of the Lifeline AGM but cost $10,000 vs $3000. Still, it is one of the better ideas for a safe, mostly off the shelf solution to get a 10kWh bank into the boat at half the weight of lead acid or better.

While we are on cycle life, it is probably important to point out that any claim of more than about 2000 cycles for a battery is silly, as the aging will come into play long before that amount of cycle life is reached. A typical full time cruiser would likely only be able to cycle 365 times per year and a weekender would most likely cycle about 50 to 100 times per year. Someone using their boat only during sailing season might only cycle 25 times per year.

Based on that, it could be that getting 200 cycles from a Lifeline battery at 80% DoD could yield as much as 8 years of life. Going for 2000 cycles from a lithium bank would take 80 years and the battery would be long dead from aging before that figure is reached. Also there is the factor of fresh batteries vs aged batteries. While a lithium bank might last 3 to 5 times as long as a AGM bank and cost 3x as much, the AGM will have full capacity at each replacement point while the lithium could be down 12% capacity at the first replacement point and 24% capacity at the next due to age. Plus there is the opportunity cost of the money used up in the initial investment, which is negligible in this low interest rate environment but might be significant down the road.

The weight and size are the big factors and probably the one reason I am still considering lithium even with the extra cost. Weight wise, I could probably get 20kWh to 30kWh for the same displacement as 10kWh of the lead acid.

Non bs maybe, but a very specific case. Many of us cycle our batteries 365 1/4 times per year, not 20 times.

Some of us even live somewhere other than the USA!

In Australia lead acid batteries are much more expensive than in the US.

To the point that in our case our LiFePO4 batteries only need to last 50% longer to break even with lead acid financially.

And when you add in the other benefits beyond cycle life, lithium batteries become far more attractive.

[ranger58sb]

Originally Posted by KTP

I am inclined to start with eight Lifeline 12V AGM in 125AH capacity in a group 31 case. These will fit nicely in the port and starboard storage under the seats in the main cabin which is fairly low and balanced. At 74 pounds each, this would be 592 pounds, or about 90 pounds less than the old engine and fuel. At 48V nominal and 250AH, draining the batteries 50% at a 8 hour rate would yield 5,760Wh with a lab environment lifetime of 1000 cycles according to Lifeline data. Draining to 80% at the same 8 hour rate would yield 9,216Wh with a lab environment lifetime of approximately 500 cycles.

Did you compare to Lifeline's 6V options? 4CT (220-Ah), 6CT (300-Ah), etc.?

-Chris

[KTP]

Originally Posted by ranger42c

Did you compare to Lifeline's 6V options? 4CT (220-Ah), 6CT (300-Ah), etc.?

-Chris

I have been thinking about the 6CT 6V Lifeline but have a few questions/issues.

Are the 6V batteries built any better than the 12V for Lifeline? They don't mention any difference in cycle life in the literature.

Is there a big advantage in having one series string of eight 6V batteries to get to 48V vs two series strings of four 12V batteries (each fused) which is then paralleled?

I would get 50 extra amp hours at 48V with eight of the 300ah 6CT vs eight of the 12V 125ah 31XT. An extra 2400Wh.

The 6CT are 90 pounds vs 74 pounds for the 31XT. 20Wh per pound for the 6V and 20.27Wh per pound for the 12V (that is interesting...)

It is going to be a bit harder to fit the taller 90 pound 6CT through the hatch under the sofa cushion and fasten it down. Probably would have to go on its side. The 12V 31XT batteries can just sit in one of those premade plastic trays with a hold down strap which you can buy at marine stores. So ease of mounting in my situation goes to the 12V

With switchable banks of 48V comprised of four series 12V, I have the option of only charging one bank or only discharging one bank. For the charging, I could then use the full 60 amps from the Magnum MS-4048 inverter/charger to bulk charge four of the 12V at a time, which would be 0.5C and probably make them happier in cases where they have been greatly discharged recently? With the 300A six volt, the most I can ever charge is 0.2C.

What do you think?