Realistic non-bs comparison of lithium to lead

[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.

[Adelie]

I'm not at all a fan of AGM, the downsides are too high and ultimately too expensive. If money weren't an issue for me I would go for Firefly AGMs which can go to 80%DoD regularly. I wouldn't believe it except MaineSail supports them.

As I am money constrained I have gone with Trojan T-1275 golfcart batteries.

[KTP]

Originally Posted by Adelie

I'm not at all a fan of AGM, the downsides are too high and ultimately too expensive. If money weren't an issue for me I would go for Firefly AGMs which can go to 80%DoD regularly. I wouldn't believe it except MaineSail supports them.

As I am money constrained I have gone with Trojan T-1275 golfcart batteries.

It would be nice if you would list the downsides.

They have a lot of upsides.

1) Available from many sources in many areas and in stock at most places

2) Very tried and true technology, trusted by insurance companies

3) Published lab data from manufacturer and backed up by years of use in the field.

4) Pretty much zero maintenance compared to flooded lead acid

5) Very little to no chance of spillage, very little to no outgassing, very little corrosion of adjacent electronics or connections

6) For the Lifelines, they can handle super large bulk charging, probably far more than you could find a charger to provide and the Lifeline batteries can be equalized which is a rarity for AGM.

The 12V 125AH Lifeline GPL-31XT can be had for $370. If you draw it down 80% over a 8 hour rate, you can expect 1150Wh per battery, or a cost of $0.32 per Wh. Cycle life if the battery is kept in a cool area of the boat in non tropical waters and is recharged relatively promptly to full (returning to marina and plugging into shore power or using a literal boat load of solar) should be in the 200 to 500 range, which would be pretty bad for full time daily use but quite well for weekend and seasonal use.

The Firefly is a very nice battery but only one source and it is $500 for 12V 110AH (same weight as Lifeline 125AH). That source is currently out of stock too. They don't have any documentation that I have found which charts out cycle life and the batteries have not really been around long enough to find examples of people using them for years and years. Still, the Firefly is under consideration. Why has this technology not been licensed out to other manufacturers?

[Adelie]

Typical AGMs are more intolerant of PSoC operation. If you can't regularly get them back to 100% then capacity suffersn more compared to FLAs.

My understanding is that real world AGM cycle life is less than FLAs.

Comparative availability will depend on where you go. If you go cruising outside the developed world then replacement AGMs become more questionable.

Maintenance free is a double edged sword. It means that you can't maintain it if you mistreat it.

Outgassing and acid fumes from FLAs can be dealt with using Hydrocaps.

For AGMs you need to be careful about your charging sources. If there isn't a good regulator you can fry your alternator.

AGMs like to be charged hard. Lifeline indicated that their AGMs should be bulk charged at .2C. For your proposed 1,000a-hr bank that's 200amps. So in addition to the extra expense of the batteries you need to pony up for a super high output alternator, a serpentine belt to drive it and a regulator that can handle it.

For an AC charger you would probably be running about 25amps which will be close to the limit of the dock service during initial bulk charging and wouldn't want to run any other appliances on the boat for a bit but it's doable.

High bulk charging rates are only going to save you 30-45min on a normal 6-7hr charging cyle from 50% DoD. If you recharge from 70% capacity remaining you may never be in bulk charging and there will be no time savings.

https://forums.sailboatowners.com/in...choice.124973/

A key consideration is intended use. You seems to be indicating you will be mostly daysailing with occasional longer trips. AGMs will be OK for this.

My boat has a small outboard for propulsion so I don't get any charging from that. Even laid up I don't have shore power so ALL charging is solar. I am debating what motor to replace the current on with and 1 option had up to 6amps of charging. Still not enough to provide the high currents recommended.

[KTP]

I went back and checked on stock of the Firefly batteries at Fisheries and I do see that the 4V@425AH L16 cells are in stock! $659 each.

(Some confusion here because in the picture printed on the cell it says 4V@450AH at the 20 hour rate but the literature says 4V@425AH at 20 hr rate)


Ok, so now consider this. 12 of those would be 48V @ 425AH (or 450AH?)

That is 16,320 Wh at the 20 hour rate and 80% DoD! That would be 48V at 21.25A going to the electric drive, or about 1kW, which I have some indication could push our displacement hull at 2.8 to 3 knots in calm water. This would give nearly a 60 nm range at very slow speeds. Alternatively, it is likely we could do 5 to 5.5 knots at 5kW to the motor, giving us probably a 12 to 15 mile range at a quite reasonable speed (again in calm water).

They are 94 pounds each, so not exactly featherweight and 12 of them would put us somewhat over the 700+ pounds of engine/tank/fuel that was removed, but we could discard the two existing house batteries and use a 48V to 12V DC-DC converter for lights + electronics which would be a negligible load on a 16,320 Wh bank. Thus really we would be only adding a couple hundred pounds to the boat over the former diesel engine and support equipment and have a honkin house battery when on the hook for several days.

Cost for 12@$659 would be $7908 plus 10% tax (bummer) vs Lifeline 16@$370=$5920 no tax (free shipping).

Lifeline expected life is 500 cycles at 80% DoD, probably more in the range of 200 cycles if abused and not fully recharged. The L16 from Firefly says an amazing 4900 cycles at 50% DoD and 1500 cycles at 80% DoD. This rivals lithium, with the only big downside being the weight. If only we could remove 2000 pounds of keel...

[skipmac]

Here's my take on AGMs in general.

Originally Posted by KTP

It would be nice if you would list the downsides.

Compared to FLA or LiFePO? Compared to FLA bateries

They have a lot of upsides.

1) Available from many sources in many areas and in stock at most places

Not any advantage over lead. Trojan and other quality brand 6V FLA batteries are more readily available than most any other suitable battery.

2) Very tried and true technology, trusted by insurance companies

Again, no advantage over FLA batteries. Have never had an insurance company mention an issue with FLA batteries.

3) Published lab data from manufacturer and backed up by years of use in the field.

Even more years of experience with FLA batteries.

4) Pretty much zero maintenance compared to flooded lead acid

In general that is true but my experience with FLA batteries I have to add a bit of water a couple of times a year. Not exactly a deal breaker.

5) Very little to no chance of spillage, very little to no outgassing, very little corrosion of adjacent electronics or connections

I'll give the first two points to AGMs but have not had any problems with the corrosion. Maybe because I have my batteries isolated from my electronics and well ventilated.

6) For the Lifelines, they can handle super large bulk charging, probably far more than you could find a charger to provide and the Lifeline batteries can be equalized which is a rarity for AGM.

I think you hit one point exactly. Will you have a charger or charging system that has the capacity to slam a lot of amps into the AGMs during the bulk charging phase? Even if you do, once the AGMs reach partial charge, certainly when they reach absorption phase, this advantage is completely gone. In tests recharging AGMs vs FLA the time to full SOC is only very slightly different. So similar as to not really make any difference in real world usage.

The 12V 125AH Lifeline GPL-31XT can be had for $370. If you draw it down 80% over a 8 hour rate, you can expect 1150Wh per battery, or a cost of $0.32 per Wh. Cycle life if the battery is kept in a cool area of the boat in non tropical waters and is recharged relatively promptly to full (returning to marina and plugging into shore power or using a literal boat load of solar) should be in the 200 to 500 range, which would be pretty bad for full time daily use but quite well for weekend and seasonal use.

The Firefly is a very nice battery but only one source and it is $500 for 12V 110AH (same weight as Lifeline 125AH). That source is currently out of stock too. They don't have any documentation that I have found which charts out cycle life and the batteries have not really been around long enough to find examples of people using them for years and years. Still, the Firefly is under consideration. Why has this technology not been licensed out to other manufacturers?

[Red Herring]

The Wynnes cover the pro's and cons pretty well in this video.

https://www.youtube.com/watch?v=J-kND4PaZm8

hth.

[KTP]

Not sure that I really think the Wynns know much of anything...don't they just repeat what the battery installer told them?


A little disenchanted now with the Firefly after finding out that Fisheries in Washington only has stock of ONE 4V 450AH battery and unknown lead time for the remaining. Also am not too fond of the mention that the battery can leak acid for the first 20 to 30 cycles (and found a user who has had this happen). Where I am placing the batteries I really do not want to have acid leaks. Evidently in India they overfill the battery and let the excess leak out during initial charging cycles, or something like that.

So it is back to tried and true Lifeline AGM for now.

[john61ct]

Can't go wrong there.

Firefly I am confident that long-ago leak issue has been dealt with via subsequent QA. That said I would only buy them for unavoidable chronic PSOC, and then only deal with Bruce's distribution network. And yes still a 4-6 month wait last I heard.

LFP greatly depends on deep pockets and ready to put in the required attention to details to stand a chance getting ROI, such long a period makes it risky. But some enjoy the bleeding edge, racing yachts where every kg saved is worth a boat buck, there are use cases.

And no the Wynns cute as they are, do not have technical depth.

[jamhass]

"Cost for 12@$659 would be $7908 plus 10% tax (bummer) vs Lifeline 16@$370=$5920 no tax (free shipping)."


Do your costs include the appropriate charge management system for the Li?

[john61ct]

I believe that was FF vs LL, LFP would never be that cheap.

[KTP]

Originally Posted by john61ct

I believe that was FF vs LL, LFP would never be that cheap.

Yes that was 48V @ 450AH of FireFly in twelve 4V cells compared to 48V @ 500AH of Lifeline AGM in sixteen 12V batteries.

LFP from Victron or something is probably around double the cost of FF or LL

Victron uses Winston? cells made in China
Firefly uses its own technology made in India
Lifeline is made in the USA

Right now if I were going to go Lithium I probably would look strongly at Torqeedo. It is just that they really designed their batteries around their own outboard drives which I don't particularly want to use. They use cells made in Japan, very high quality. I actually have one of their older Torqeedo 1003 with the small 300 watt pack which is now about 9 years old and it still has at least 3/4 of the original capacity if not a bit more. I like their 26V 104AH batteries on paper. Those are about 2700Wh and are around $2200. Just absolutely bullet proof. Each cell has a safety device, the whole battery has tons of safety devices, heck the thing is submersible for an hour with a water sensor to cut off power to the terminals. The problem is they are very much designed around Torqeedo's drives. You have to have a charger for each battery and a key switch for each battery if they are not connected to a Torqeedo motor. It starts adding up, like $700 to $1200 for each battery in extra components unless I am missing something.

Expensive though. It would be $20,000 for a 52V 416AH pack, but boy would it be sweet.

[GrowleyMonster]

Lifelines look good to me if you simply must go AGM. Myself, I went with FLA 220ah 6v golf cart batteries, $85/ea from Sams Club for my 48v propulsion bank. That was 4 years ago. Still going strong. I plan on doing a full 20hr rate discharge test sometime this year to see just how strong they still are, but resting voltage testing vs watts used still shows slightly better capacity than they had when new, around 220ah. I don't regret the purchase. In fact I will be installing a second bank of the same thing this winter, along with my solar canopy.


I did the math and LiFeP04 comes out more expensive no matter how you slice and dice it. FLA is well known and understood, proven technology. Like I said, I am 4 years into these batteries and no sign of weakening yet. I honestly expect to get 6 years out of them. Yeah I had to check the batteries and fill them. I equalized every once in a while. I monitored them carefully when charging. Still way less maintenance than a diesel. And I didn't have to trust a BMS to keep them safe and healthy. Not knocking the various lithium types but for me the choice was mostly dictated by out the door cost of the entire storage and charging system. Turns out the choice was a good one, at least for me.

[KTP]

Growl, can your Cal 2-27 at 6700 pounds displacement handle an extra eight of the 6V 220AH FLA? That would be about...750 pounds? The first eight you installed I assume you recouped the ~600 pounds of engine + fuel tank. I know when we just took out our 30HP Yanmar the boat popped up about an inch or two, showing a nice scum line that used to sit underwater

Our boat displaces something like 13,500 though (with the engine in). It will actually be lighter with the eight Lifelines, 48V at 250AH than it was with the engine + fuel/tank.

The lead acid is cheap enough though that I wish we could take some of the 4500 pounds of keel out and replace that with battery too. I have been looking at where the funky shaped diesel tank goes (right on top of the keel) and pondering how I might squeeze some form factor of Lifeline on top of that. None of them really fit well there, except probably I could fit in four of the 31 size. I plan to put the initial eight GPL-31XT 12V 125AH four on each side of the cabin under the sofa seats. I don't like accessing those compartments anyway so set and forget AGM seems perfect there. Then perhaps four more in place of the diesel tank for a total of twelve, 48V @ 375AH, 18,000Wh at a cost of $4,476. I would charge them with a Magnum MS-4048 inverter/charger (4.8kW AC output, 48V input) which has a max charging current of 60 amps. This is 30 amps per string when I have eight Lifelines, which is an acceptable current. A little light on the charging when eventually I have twelve Lifelines at 20 amps per series string but I doubt it will hurt the cycle life that much to charge them at that level (0.16C)

You just can't get 18kWh of LFP for anywhere close to $4500 or even 9kWh.

[GrowleyMonster]

Originally Posted by KTP

Growl, can your Cal 2-27 at 6700 pounds displacement handle an extra eight of the 6V 220AH FLA? That would be about...750 pounds? The first eight you installed I assume you recouped the ~600 pounds of engine + fuel tank. I know when we just took out our 30HP Yanmar the boat popped up about an inch or two, showing a nice scum line that used to sit underwater

Our boat displaces something like 13,500 though (with the engine in). It will actually be lighter with the eight Lifelines, 48V at 250AH than it was with the engine + fuel/tank.

The lead acid is cheap enough though that I wish we could take some of the 4500 pounds of keel out and replace that with battery too. I have been looking at where the funky shaped diesel tank goes (right on top of the keel) and pondering how I might squeeze some form factor of Lifeline on top of that. None of them really fit well there, except probably I could fit in four of the 31 size. I plan to put the initial eight GPL-31XT 12V 125AH four on each side of the cabin under the sofa seats. I don't like accessing those compartments anyway so set and forget AGM seems perfect there. Then perhaps four more in place of the diesel tank for a total of twelve, 48V @ 375AH, 18,000Wh at a cost of $4,476. I would charge them with a Magnum MS-4048 inverter/charger (4.8kW AC output, 48V input) which has a max charging current of 60 amps. This is 30 amps per string when I have eight Lifelines, which is an acceptable current. A little light on the charging when eventually I have twelve Lifelines at 20 amps per series string but I doubt it will hurt the cycle life that much to charge them at that level (0.16C)

You just can't get 18kWh of LFP for anywhere close to $4500 or even 9kWh.

You know, sometimes you don't realize how much heavy stuff you have on a boat that you are always tinkering with as well as living aboard. When I sorta moved in with the GF I got all my razormaking stuff off, all the spare or wanna try it motors and gearboxes, clothes, most of my tools, books, linen, pots and pans, paint, resin, steel, aluminum, nuts and bolts and other hardware, shafting, couplings, and just plain junk off the boat and I figure it totaled well over 1000lb. So now I'm putting about 700 lbs of batteries more on, as well as probably 250lbs of solar. She will be over the marks but not too bad.


If LFP were cheap I would probably go with them even considering needing a BMS, etc. They really are marvelously light and power dense. They just cost too darn much even when you factor in the lifespan and DOD. I figured if I took good care of the golf cart batteries they would treat me nice, and I was right. Pretty sure they will outlast most AGM too. I seriously dislike all sealed lead acid batteries. You don't have to check the water. You CAN'T check the water. You don't have to equalize. You CAN'T equalize. generally. One thing in favor of AGM that I admire, though. You can install them pretty much in any orientation works for you. This can be a big plus in a very small boat where you want to use up all the little nooks and crannies and voids and under settee spaces.


My GF has a little 19' Halman in the slip next to my boat. Salty little boat, but the operative word is "little". If I were putting in a propulsion bank in that little tonka toy boat I would almost be inclined to go LiFeP04, especially since it would be her money LOL! With lead, I would have no choice but to go AGM. I put two golf cart batteries in series over her keel for a house bank and it takes up virtually all the space down there. It would be virtually impossible to mount 8 of them, even 6 of them due to lack of space. Also I am no jockey and she is no gymnast. Together we set the poor little boat down pretty deep and make the self bailing cockpit nearly into a self filling cockpit so with that little tub even a 36v bank of FLA would be too heavy. The engine is an outboard so there is nothing heavy to take out of the boat. So sometimes FLA simply will not do. Something displacement-ish at over 4000lb, that's a different thing.


Yeah it would be nice to turn the weight of FLA batteries into an asset. A purpose built boat, with a full keel and the batteries stuffed down there above the solid ballast, would be nice. You could actually build the boat around a bank of L16s or maybe some 2000ah telephone exchange cells, and have a whopping bank, yeah. You would of course want multiple high quality bilge pumps, and good battery boxes, to keep your flooded cells from getting flooded with bilgewater. Just sayin.