Lithium Batteries (for the rest of us)

[hellosailor]

Don, the advantage is that a lithium bank will charge at least 4x-5x faster, can be discharged to at 2x-3x the depth, will provide 4x-6x more discharge cycles, and will take up 1/4 of the weight and space compared to lead acid.

So in theory, you're getting way more "everything" and the only drawback is the purchase cost, which in theory will still be a bargain because the batteries will provide so many more cycles.

The world is just waiting for some objective sources to do a five-year test to see how these things really play out. (Except perhaps for Boeing, they've adopted one of the different lithium technologies and after five years "oops" seem to apply.)

[sailorboy1]

Originally Posted by hellosailor

Don, the advantage is that a lithium bank will charge at least 4x-5x faster, can be discharged to at 2x-3x the depth, will provide 4x-6x more discharge cycles, and will take up 1/4 of the weight and space compared to lead acid.

So in theory, you're getting way more "everything" and the only drawback is the purchase cost, which in theory will still be a bargain because the batteries will provide so many more cycles.

The world is just waiting for some objective sources to do a five-year test to see how these things really play out. (Except perhaps for Boeing, they've adopted one of the different lithium technologies and after five years "oops" seem to apply.)

So if the batteries can do 4X the cycles (life) and they cost about 4 times as much then that is a wash (in the 20+ year run).

If they can be discharged further are we saying that you could use a house bank of half the size as a lead acid bank?

Charging seems to depend a lot on how you charge your batteries to start with and then the amount of upgrades you might spend on say alternators. If you are charging with solar you probably are already accepting as much charge as you can produce.

I'm just asking as I'm not seeing much useful advantage in the advantages.

[goboatingnow]

just a few perspectives from somebody using lithiums in designs ( small ones < 20WH)

* The technology is well understood, however the industry does suffer from quality issues, especially in Chinese stuff.

* Li is in use now for about 5 years

* TOday , with the costs premiums you do not have a monetary advantage ( especially over "average LA").

* You have a number of technical advantages, virtually flat discharge curve, higher recharge ( may not be a real advantage), greater cycle life ( for Li Ferrous only), high discharge currents ( may not be useful), lower weight,smaller, less complex charging and virtually zero maintenance.

* Capacity , well hmm here, in reality to be sure to be sure, many people are using Lithiums from about 90% to about 30%, giving them about 60% capacity, over about 50% capacity with LA ( or more with tubular traction LA)

* Big advantage of Li is you dont need to recharge to 100% , thats a big advantage on a boat , Li benefit from being undercharged , LA dies because of it.

So if today , your bank is made up of medium costs LAs, youll find it hard to justify the cost of LiFePO4, never mind the possible change out of certain charges sources.

If on the other hand you were considering high end LA, or maybe cell level traction LA, then LI is a serious contender.

Horses for courses.

dave

[Maine Sail]

Originally Posted by Don L

I must be missing something. From reading this thread and a little of the other, near as I can tell it will cost 4 times the cost of a 6V LA house bank for the batteries PLUS you have to apparently change a lot about your charging system.

Just what is the big plus of these lithium batteries to justify such costs and efforts?

Minus labor, about 95 hours, I am into my 400Ah bank for about $1800.00 in materials. However I already had much of the equipment others would need to buy such as the regulator, large alternator, alt temp sensor, serpentine pulley kit etc. etc. etc.. (much of this stuff you'd need for a large FLA or VRLA bank anyway) I am more into my bank for my own educational and experimental purposes. I don't "need" this bank....

The pluses are that you can use 80% of the capcity where as with LA you get to use only 30-35% once more than a day away from a full charge. This means you are carrying around 65-70% of your bank as dead weight. Li also weighs a lot less.

They also claim 2000 - 3000 cycles at 80% cycle depths (believe it when I see it)... They also charge to full with no acceptance limiting. This means use 50Ah's put 50 Ah's back as fast as you can stuff it in... With LA you can only go so fast, especially once you've hit an absorption voltage.....

Also equipment LOVES Li.... My Espar has never run so well, my stereo plays louder, and sounds better, in short everything just seems to run better at 13+V vs. 12.4V +/-.... I've not yet seen my bank dip below 13.1V during normal use. The bank does not even notice the motor getting started...

Don't kid yourself FLA batteries are still a great value and until you regularly get 7-10 years out of FLA banks, as a seasonal coastal cruiser, I would not suggest moving to Li.

Hell I could have done an FLA bank for $240.00 and gone another 8 years on it like the last bank (that is still going strong BTW) but this was more fun..

[nimblemotors]

Originally Posted by Don L

I'm just asking as I'm not seeing much useful advantage in the advantages.

I hope the FUD didn't scare you.
The main advantage is the size/weight. If space and weight are not a big deal to your boat, then probably isn't worth it. For a multihull, weight is a big deal, for a monohull, I'd think space would be, but clearly it is your call.

For long term cyclelife, A123 had tests on electric buses, and found if I recall real-world 3x lifetime over lead acid. Which is good, but not the 10x (or 100x) they (or their fanboys) claim. It was a independant DOE or DOT report required by their funding (so liar company can't fake) can't find it easily, so my memory could be off.

[ebaugh]

Originally Posted by Don L

So if the batteries can do 4X the cycles (life) and they cost about 4 times as much then that is a wash (in the 20+ year run).

If they can be discharged further are we saying that you could use a house bank of half the size as a lead acid bank?

Charging seems to depend a lot on how you charge your batteries to start with and then the amount of upgrades you might spend on say alternators. If you are charging with solar you probably are already accepting as much charge as you can produce.

I'm just asking as I'm not seeing much useful advantage in the advantages.

Strictly on cost, vs wet golf cart lead acid cells is at best a wash. If you have the space, and can carry the weight, banks made from true 2V traction batteries, lead acid is cheaper. However, compared to AGM or Gel, LFP is only slightly more to install (assuming you can tweak your charging system), and probably 1/2 the long term cost if the cycle life claims pan out.

I call the usable range something like 15-85% SOC give or take a little. So call it 70% usable capacity for LFP versus 50% for LA based on a full cycle, but if you mostly run your lead acid between 50% and 80%, then it's 70 vs 30%. If thats the case, it would probably be safe to scale back a replacement LFP bank capacity by 20-30%. But by the time someone is sold on the concept, few probably do. I kept the same rated capacity.

If you run a solar/wind deficit, or don't have solar/wind, LFP will save some engine/generator run time at anchor.

[ebaugh]

Originally Posted by Maine Sail

Don't kid yourself FLA batteries are still a great value and until you regularly get 7-10 years out of FLA banks, as a seasonal coastal cruiser, I would not suggest moving to Li.

Hell I could have done an FLA bank for $240.00 and gone another 8 years on it like the last bank (that is still going strong BTW) but this was more fun..

This statement confuses me a bit...

I would say if you wear out (like I did) a LA house bank in 1-2 years (500 cycles), LFP may make sense. If you can get 7-10 years from LA, don't switch based on cost, it's unknown for sure, but there is a reasonable chance LFP will have a calendar life of something like 10 years, regardless of cycles.

I think the first test (not the only one) for anyone is; are you off grid (mooring or anchor), living aboard at least 90, probably 180 days a year or more? If not, I would rule out LFP unless weight is critical. They won't save much space unless you reduce rated capacity.

[hellosailor]

Maine-
"They also claim 2000 - 3000 cycles at 80% cycle depths (believe it when I see it)..."
Now, if you had just bought a single 100AH battery, you could have cycled that 80% three times a day and given us a report on how it holds up after a thousand charge cycles in just one year. Gonna need a bigger hot water heater to cycle the bank you've got.<G>

[Maine Sail]

Originally Posted by ebaugh

This statement confuses me a bit...

I would say if you wear out (like I did) a LA house bank in 1-2 years (500 cycles), LFP may make sense. If you can get 7-10 years from LA, don't switch based on cost, it's unknown for sure, but there is a reasonable chance LFP will have a calendar life of something like 10 years, regardless of cycles.

I think the first test (not the only one) for anyone is; are you off grid (mooring or anchor), living aboard at least 90, probably 180 days a year or more? If not, I would rule out LFP unless weight is critical. They won't save much space unless you reduce rated capacity.

I was talking in the opposite spectrum. A coast cruiser does not "wear out" FLA batteries via "cycles" they KILL them from bad practices. I see two to three year old dead banks with well under 100 true cycles on them on a near daily basis..

My point was/is if you can't take care of FLA batts enough to get 7-10 years of "seasonal coastal cruising" then you are likely going to destroy Li batteries too. My point is to work on your battery management practices & get them dialed in before you plunk down big cake/$$$ on Li.......

If you actually wear out FLA batts due to cycles then Li is a great fit.... This is why I specifically mentioned "seasonal coastal cruising"...

Honestly I replace sooooo many batteries with less than 100 cycles on them that it is not even funny.. When those customers ask "what batteries should I buy?".. The answer is the cheapest you can possibly find because you're just going to kill them anyway...

I've got one guy with a 34 footer who runs a single group 27 and has refrigeration. Can't talk him into anything but. He's on his third fridge compressor but "knows" it's not from the chronic low voltage he's feeding it... He gets one season out of a battery and accepts that and thinks it is normal. Forget getting back to 80% he's lucky to get back to 60% SOC.... he'd be a bad candidate for Li....

[mcarling]

Originally Posted by ebaugh

Inside of the case are 4 individual cells that need to be monitored for maximum life.

The same could be said about lead acid batteries -- except that 12V lead acid batteries have 6 cells that need to be monitored for maximum life, not 4 cells.

The reality is that the hassle of monitoring individual cells to squeeze some extra life out of the batteries deters almost everyone from monitoring individual lead acid cells. I expect the same will be true for LiFePO4 cells once the market grows past the early adopters who like to tinker.

[conachair]

Maybe for the lower usage boats for now.....

Small in size, big on power: New microbatteries a boost for electronics | News Bureau | University of Illinois

[sailorboy1]

So if I'm understanding, it sounds that biggest advantage of the lithium is if you are running your engine or a generator JUST to recharge you batteries????

[skipmac]

Originally Posted by Don L

I must be missing something. From reading this thread and a little of the other, near as I can tell it will cost 4 times the cost of a 6V LA house bank for the batteries PLUS you have to apparently change a lot about your charging system.

Just what is the big plus of these lithium batteries to justify such costs and efforts?

Well gee Don. If you had read the 4,892,615 posts in the other LiFePO thread you would know all about that.

From what I can tell a couple of advantages.

1. Can charge and recharge at a very high rate so reduced charging times and you can draw high current from the batteries without losing the rated capacity. So a 200 amp hour battery will give you the same number of amp hours whether you pull it at 0.1 amp/hour or 100 amps/hour.

2. Can use more of the rated capacity of the battery without killing it. So for a lead acid battery most off the grid cruisers use the batteries from 80% to 50% state of charge. With LiFePO you can use more. How much?

[Caracal]

Originally Posted by Don L

So if I'm understanding, it sounds that biggest advantage of the lithium is if you are running your engine or a generator JUST to recharge you batteries????

Or lots of solar and/or a big hydro generator, methinks.

In reality, I think that quick charging off of the engine or a generator is a good enough reason to do it (provided you want to keep an eye on it), even if the usable capacity was the same as lead acids.

[nimblemotors]

Originally Posted by Don L

So if I'm understanding, it sounds that biggest advantage of the lithium is if you are running your engine or a generator JUST to recharge you batteries????

No, you didn't read my post. They are lighter and smaller (for given usable capacity). AGM lead acid can be recharged quickly, but as noted, they are not 4x cheaper than lithium, nor last nearly as long as flooded lead acid (golf cart batteries), so lithium may in fact be cheaper than AGM.
I haven't done detail comparisons for years, for cars and my multihull, the weight issue clearly rules out lead acid.