Is a new-build without lithiums just plain stupid???

[sbman]

I chose FLA for my boat after an extensive refit. This was solely driven by upfront cost. My use case is completely off grid/solar dependent, no shore power, LFP would be the better technical choice and a savings in the long run. However, a trip to Costco netted 10kW of FLA GC2 batteries that should last 2-3 years for about 1 boat buck.

The cost considerations in the face of a new build would not seem to be as significant and the use case would be a much bigger driver.

Per the OPs concern of lightning strikes damaging the BMS, if the BMS is damaged by a strike, what might be left to power on anyways?

One thing I really don't like about the 'drop in' lithium solutions is that the BMS is likely to be the weak point and it is sealed up in a box you can't access. A couple of bad FETs in the disconnect circuit and you've got a bunch of otherwise good cells in a box that isn't usable.

 

[JDCAVE]

I’m sitting on the fence! A picket fence and my but is sore!

I have 10 T-105’s with 8 years of service in them. They are cabled series-parallel for a 12 VDC house bank. They currently drink 2 litres of distilled water every two months or so. I’m comfortable with them and they are easily accessed for watering.

I have 435 watts of solar. The bank seldom goes below 80% SOC. More normally not less than 85%. That’s rated capacity. I have never reset the system for less than 1125 amp hours. Last spring I ran a 30 hour test with no shore or solar charging and the resting voltages, no load, we’re consistent the the SOC, at 70%. That implied to me that the bank was healthy prior to cruising.

Last summer I used the brand new Northern Lights to put a thump into the bank and then let either the solar or alternator take over. Most days the bank got to float charge on solar by the end of the day.

So I have considered LFP, but it’s a lot cheaper to go with a 900 amp hour T-105 bank that get 400 amp hours of LFP. I would also have to consider a Sterling and a couple of other devices to upgrade fail safe measures. I’ve read through the Compass Marine site on LFP several times and quite frankly, I don’t need the grief. Money tight right now and the last thing I need is a failure in an LFP bank.

So that’s where I am right now. T-105’s are $240 CDN a piece. So about $2,000 to replace them…or I could take a chance on another year with the existing system. I’m not sure that’s a good idea.

I haven’t priced out an LFP option.

Jim

 

[sbman]

I’m sitting on the fence! A picket fence and my but is sore!

I have 10 T-105’s with 8 years of service in them. They are cabled series-parallel for a 12 VDC house bank. They currently drink 2 litres of distilled water every two months or so. I’m comfortable with them and they are easily accessed for watering.

I have 435 watts of solar. The bank seldom goes below 80% SOC. More normally not less than 85%. That’s rated capacity. I have never reset the system for less than 1125 amp hours. Last spring I ran a 30 hour test with no shore or solar charging and the resting voltages, no load, we’re consistent the the SOC, at 70%. That implied to me that the bank was healthy prior to cruising.

Last summer I used the brand new Northern Lights to put a thump into the bank and then let either the solar or alternator take over. Most days the bank got to float charge on solar by the end of the day.

So I have considered LFP, but it’s a lot cheaper to go with a 900 amp hour T-105 bank that get 400 amp hours of LFP. I would also have to consider a Sterling and a couple of other devices to upgrade fail safe measures. I’ve read through the Compass Marine site on LFP several times and quite frankly, I don’t need the grief. Money tight right now and the last thing I need is a failure in an LFP bank.

So that’s where I am right now. T-105’s are $240 CDN a piece. So about $2,000 to replace them…or I could take a chance on another year with the existing system. I’m not sure that’s a good idea.

I haven’t priced out an LFP option.

Jim

If you are referring to the Sterling Pro Charge as a house bank charger for LFP, I would not recommend it. You cannot control how long it holds the absorb voltage (as is the case with almost all chargers designed for Pb) and it can and will hold it for up to 10 hours.

I'm replacing one right now after talking with Sterling about it, they tell me to just not worry about keeping the brand new Lithiums at 14.4 for hours after every charge. The manufacturer of the batteries and all other indicators say to get down to a 13.4-13.6 soon after the absorb voltage is reached. The lithium setting on the Sterling does nothing to shorten the absorb time, just sets the voltages for float and absorb.

 

[DDW]

The fact is that a well designed FLA system will fully recharge pretty quickly in a power boat once underway mitigating the undercharging concerns.

You must differentiate FLA from AGM in this regard. FLA batteries can be run at a partial state of charge for weeks at a time, followed by an equilizing charge, without much degradation. They sulfate, but the equilizing charge drives the sulfate off. AGM batteries generally cannot be equalized, because there is no way to replace the lost electrolyte. You get a meaningful charge pretty quickly, but it requires 4 - 6 hours charge to fully charge AGMs and there is nothing you can do to change that. If you are charging less than this per day for long periods, their life will be short.

I just replaced my batteries with AGM after considering LFP, because we typically run at least 4 hours every day, and store the boat for many winter months unused. But last summer confined by Covid to Puget Sound, daily runs were 2 hours or less. That made battery management more difficult, if that continued FLA or LFP would have been a better choice.

See my comments in red above.

The thing wrong with your analysis is use pattern. 6 years on FLAs that have a life of 500 cycles means you are cycling them on average 7 times a month. That is a weekend user, and FLA or AGM are not a bad choice for a weekend user. If you are living on board at anchor, in those same 6 years you will cycle the batteries over 2000 times, and have to replace your FLA bank 4 times as often as your analysis assumes. Run that again and see how that looks.

With current technology and pricing, you cannot say LA or LFP are better, without first specifying the use case as the answer is meaningless without doing so.

 

[sbman]

...
The thing wrong with your analysis is use pattern. 6 years on FLAs that have a life of 500 cycles means you are cycling them on average 7 times a month. That is a weekend user, and FLA or AGM are not a bad choice for a weekend user. If you are living on board at anchor, in those same 6 years you will cycle the batteries over 2000 times, and have to replace your FLA bank 4 times as often as your analysis assumes. Run that again and see how that looks.
...

You could be on the hook for years with FLA if your daily cycles are shallow and you do reasonable maintenance. Oversize the bank enough that you aren't doing full cycles and have a reliable frequent charge source can do the trick.

Real cycles to 50% are where you are going to see FLA wearing out in the 400-600 cycle range. This is the scenario where LFP makes sense, and if you oversize an LFP bank and ensure you stay within it's envelope you'll probably never have to replace them even living on the hook full time.

Putting an LFP system in a new boat and not having to worry about batteries during the expected ownership timeframe seems pretty attractive

 

[JDCAVE]

If you are referring to the Sterling Pro Charge as a house bank charger for LFP...

Actually I was wrong. The regulator I was thinking of was made by Wakespeed, not Sterling.

Jim

 

[catalinajack]

You could be on the hook for years with FLA if your daily cycles are shallow and you do reasonable maintenance. Oversize the bank enough that you aren't doing full cycles and have a reliable frequent charge source can do the trick.

Real cycles to 50% are where you are going to see FLA wearing out in the 400-600 cycle range. This is the scenario where LFP makes sense, and if you oversize an LFP bank and ensure you stay within it's envelope you'll probably never have to replace them even living on the hook full time.

Putting an LFP system in a new boat and not having to worry about batteries during the expected ownership timeframe seems pretty attractive

In a new boat, the original question, yes it makes sense in that the cost is minimal relative to the overall cost of the boat.

 

[catalinajack]

You must differentiate FLA from AGM in this regard. FLA batteries can be run at a partial state of charge for weeks at a time, followed by an equilizing charge, without much degradation. They sulfate, but the equilizing charge drives the sulfate off. AGM batteries generally cannot be equalized, because there is no way to replace the lost electrolyte. You get a meaningful charge pretty quickly, but it requires 4 - 6 hours charge to fully charge AGMs and there is nothing you can do to change that. If you are charging less than this per day for long periods, their life will be short.

I just replaced my batteries with AGM after considering LFP, because we typically run at least 4 hours every day, and store the boat for many winter months unused. But last summer confined by Covid to Puget Sound, daily runs were 2 hours or less. That made battery management more difficult, if that continued FLA or LFP would have been a better choice.



The thing wrong with your analysis is use pattern. 6 years on FLAs that have a life of 500 cycles means you are cycling them on average 7 times a month. That is a weekend user, and FLA or AGM are not a bad choice for a weekend user. If you are living on board at anchor, in those same 6 years you will cycle the batteries over 2000 times, and have to replace your FLA bank 4 times as often as your analysis assumes. Run that again and see how that looks.

With current technology and pricing, you cannot say LA or LFP are better, without first specifying the use case as the answer is meaningless without doing so.

Use case is important. Certainly for those who are constantly away from shore power would see a shorter break-even point but many who read these posts and are considering a changeover would not based on their particular use case. Many of our readers are indeed "weekend users" and would see a very protracted break-even period. So, change the use case to 250 cycles per year. In four years that would mean a FLA cost of $2,400. In eight years the cost would be $4,800 years. So, an 8-year break-even period at the very least. So, riddle me this. What percentage of boaters do you think come anywhere close to this use case? A guess? Maybe 5%, probably fewer. Remember, I was responding to the poster who suggested a 2-3 year payback. In my opinion, most boaters, certainly not all, but most will never see a payback from a changeover to LFP. I would suggest to anyone considering doing so to run the numbers on their own use profile to determine whether it is worth the up-front expenditure.

 

[twistedtree]

Another thing that ages LA batteries quickly is only charging through bulk while at anchor. People seem to do this quite commonly to maximize the use of generator run time, then rely on a long run underway with alternator(s), or a return to shore power to fully recharge and hopefully de-sulfate. With LFP this whole dance completely goes away.


I'd also like to reinforce that Battleborn batteries are VERY expensive. My MG battery system with dual BMSes, metal battery cases, touch displays, and active control of charging sources cost about 60% of Battleborn's cost. So top quality LFP can be a lot less expensive than what people are using in many of these comparisons. Also, for me, and I expect some others, the alternative is AGM, not FLA, because we don't want the maintenance hassle of FLA, the risk of acid spills, or the explosion risk. That leaves LFP costing anywhere from 1.5 to 2x LA, not 5x.


"Premium" FLA batteries have also been mentioned, like the really big Surrette/Rolls batteries used in some boats. I had an 1100Ah, 48V bank of Surrettes for about 10 years. They were not cheap, actually very far from it. The good news is that they lasted 10 years. But over that time two of them failed and had to be replaced. The warranty was useless because it cost as much to ship me a replacement as it would have cost to buy a new one. When the second battery failed, I just bought a new one and saved a few bucks. But in both cases, it too 2-3 months to get a replacement. Yes, that's right, 2-3 months. These were primary power for my house, so I ended up cabling around the failed cell and running the system as a 44V system for the 3 months until I could swap the bad cell. Maintenance was a huge hassle as well. As the batteries aged, I was going through 12 gallons of water each time I needed to top them up. Overall it was a horrible experience and I would never buy a Surrette/Rolls battery again.


Now for the real point. When I replaced the Surrettes with LFP, the cost per usable Ah was almost exactly the same. So both were premium priced, but only the LFP has delivered premium performance. I think I'm coming up on year three with LFP, and the only maintenance I've done is a single re-balancing exercise. Other than that I have done nothing. They just work, day in and day out with no drama. In this application where they cycle at least 20-30% every day, are 90% recharged via solar, and 10% recharged via a generator, they are superior in every way to FLA, including the Trojan L16s that I had before the Surrettes.

 

[sbman]

...
Now for the real point. When I replaced the Surrettes with LFP, the cost per usable Ah was almost exactly the same. So both were premium priced, but only the LFP has delivered premium performance. I think I'm coming up on year three with LFP, and the only maintenance I've done is a single re-balancing exercise. Other than that I have done nothing. They just work, day in and day out with no drama. In this application where they cycle at least 20-30% every day, are 90% recharged via solar, and 10% recharged via a generator, they are superior in every way to FLA, including the Trojan L16s that I had before the Surrettes.

And this is the big deal. This weekend, I'm going to don some gloves and eye protection go down in the bilge and water my cheap FLA batteries, check the SG, and most likely run an equalize charge on them. Do they get the job done? Yes.

If I had just bought a brand new boat with all new systems do I really want to be down in the bilge mucking with battery maintenance to make sure I get the most life I can out of them? Do I want to be thinking about if my expensive-ish AGMs are getting enough absorb charge, often enough, but not too much?

No. I want to just use the new boat and count on the batts to do their job with no hassle and LFP can do that. I'm not sure how you factor price into that but no matter the use case there's a value to be had.

 

[catalinajack]

And another thing or two:

You must differentiate FLA from AGM in this regard. FLA batteries can be run at a partial state of charge for weeks at a time, followed by an equilizing charge, without much degradation. They sulfate, but the equilizing charge drives the sulfate off. AGM batteries generally cannot be equalized, because there is no way to replace the lost electrolyte. You get a meaningful charge pretty quickly, but it requires 4 - 6 hours charge to fully charge AGMs and there is nothing you can do to change that. If you are charging less than this per day for long periods, their life will be short.

I just replaced my batteries with AGM after considering LFP, because we typically run at least 4 hours every day, and store the boat for many winter months unused. But last summer confined by Covid to Puget Sound, daily runs were 2 hours or less. That made battery management more difficult, if that continued FLA or LFP would have been a better choice.



The thing wrong with your analysis is use pattern. 6 years on FLAs that have a life of 500 cycles means you are cycling them on average 7 times a month. That is a weekend user, and FLA or AGM are not a bad choice for a weekend user. If you are living on board at anchor, in those same 6 years you will cycle the batteries over 2000 times, and have to replace your FLA bank 4 times as often as your analysis assumes. Run that again and see how that looks.

With current technology and pricing, you cannot say LA or LFP are better, without first specifying the use case as the answer is meaningless without doing so.


I did specify a use case, 500 cycles in six years. Also, I used 500 cycles on FLA to be ultra conservative. The fact is that the manufacturer estimates 1,600 cycles at 50% depth of discharge. If you are going to accept that a Battle Born will last 3K-5K cycles as the manufacturer asserts, then for comparison you ought to accept 1,600 cycles for FLA. Doing so triples the break-even period for 250 nights/year anchored out to 24 years.

Now, you can opine that FLA will not actually last 1,600 cycles but there is no proof that LFP will last as long as advertised either. It is interesting that Battle Born also says that their batteries will last only 10 - 15 years and that their warranty is only 10 years. Consider this: using Battle Born's estimate of 3,000 cycles, their batteries will last the 250 night user 12 years, right in line with their 10 - 15 year service life. That would be a cost of $5,000 vs $4,800 for FLA using a 500-cycle life estimate! No matter how you slice it, FLP, at best, is neutral as to cost and if one goes with the FLA manufacturer's estimate of cycle life, then not even close.

And for those considering a changeover, my numbers don't consider any ancillary costs such as maybe two DC-DC chargers, switches, and cabling which could easily run to another $600 - $800 making the break-even years longer.

What bothers me about the nature of this discussion is that many of our readers are new to boating and have only a cursory understanding about these complex systems. Yet, they read about the few here who are pretty much very special users who expound on the efficacy of LFP without any caveats leading those newbies to make expensive, unneeded investments in LFP. One last not - all my numbers assume self-install. For those folks paying an ABYC electrician to do the installation, then the numbers skyrocket.

 

[twistedtree]

There is another aspect of the original questions that we largely ignored, and I think it's actually really important.


In a new build, I actually think asking about LFP is the wrong question, or more accurately, it's a consequential question, not the primary question. With a new build, I think you need to ask/explore what you want your power system to do. We have boats here on TF where running a few lights, charging a phone, and making coffee is the objective. Other boats want 24x7 AC power and freely use AC appliances. Increasingly, people are making boats all electric, doing away with propane for cooking and grilling. This excludes electric propulsion, though obviously some people are doing that too. It's been very interesting to me to hear GreenLine owners say that 24x7 "normal household power" is one of the things they like the most about their boats.


So I think the question is more around what you want your electrical system to do. Myself and others have built boats where virtually all of the on-board electrical system is behind inverters. This includes clothes washers, electric clothes dryers, electric ovens, discharge and transfer pumps. Even HVAC. The goal is to be able to run loads without having to start a generator, run off batteries until they are low, then run a generator just long enough to recharge. Our overall usage is mixed, but we all do spend a lot of time at anchor for multiple days. These systems work really well, and give you a quiet ship for all but 2-3 hrs a day. I haven't had cause to try it myself, by my friends run HVAC in their staterooms through the night 100% on battery power. My wife and I really like cooking with gas so we have kept propane for our cooktop and outside grill, but others have converted these to electric as well. The only things I have that are not powered via the inverters are the hot water electric heating elements, and the shore power battery chargers.



I think these are the things you need to be asking yourself. Retrofitting a boat to do this can be difficult if not impossible, but with a new build it's pretty easy, so now's the time to think about it.


With a system like I describe above, LFP will quickly become a necessity. High capacity batteries will be needed, as will high charge and discharge rates. LA just don't work well for a system like this unless you seriously over size the batteries. The Peukert effect of large loads on LA is just too great, and the recharge times stretch out too long.


So first look at what you want your power system to do. Then look at how to do it.

 

[Simi 60]

And another thing or two:

The issue I have is that you keep comparing cheap LA or AGM to top of the line or at least, expensive LFP to try and get your point across.

If you used Rolls Surette AGM how does it look then?

Or if comparing cheap AGM at least compare it to cheap LFP
As I have repeatedly said, we have 840ah @ 24v of LFP and that cost about $3000 usd


Compare that to battleborn and for 800 ah @ 24v it would be $14,000

What bothers me about the nature of this discussion is that many of our readers are new to boating and have only a cursory understanding about these complex systems

What's complex about it?
It's literally 2 minutes to change the setting on our inverter charger
A few minutes more on the solar MOpT

For those folks paying an ABYC electrician to do the installation, then the numbers skyrocket

If they are capable of bolting together 6 or 12v LA or AGM to get the required battery size then they should be able to bolt together 3.5v LFP to do the same.

 

[catalinajack]

The issue I have is that you keep comparing cheap LA or AGM to top of the line or at least, expensive LFP to try and get your point across.

If you used Rolls Surette AGM how does it look then?

Or if comparing cheap AGM at least compare it to cheap LFP
As I have repeatedly said, we have 840ah @ 24v of LFP and that cost about $3000 usd


Compare that to battleborn and for 800 ah @ 24v it would be $14,000



What's complex about it?
It's literally 2 minutes to change the setting on our inverter charger
A few minutes more on the solar MOpT


If they are capable of bolting together 6 or 12v LA or AGM to get the required battery size then they should be able to bolt together 3.5v LFP to do the same.

I wouldn't ever use Rolls. And I wouldn't ever consider Chinese junk. You have no idea of how long they will last. Cheap is cheap for a reason. And I compare to top of the line LFP because many folks are or have moved to those brands. They are top of the line for a reason. The Chinese products, well, you get what you pay for.

 

[catalinajack]

There is another aspect of the original questions that we largely ignored, and I think it's actually really important.


In a new build, I actually think asking about LFP is the wrong question, or more accurately, it's a consequential question, not the primary question. With a new build, I think you need to ask/explore what you want your power system to do. We have boats here on TF where running a few lights, charging a phone, and making coffee is the objective. Other boats want 24x7 AC power and freely use AC appliances. Increasingly, people are making boats all electric, doing away with propane for cooking and grilling. This excludes electric propulsion, though obviously some people are doing that too. It's been very interesting to me to hear GreenLine owners say that 24x7 "normal household power" is one of the things they like the most about their boats.


So I think the question is more around what you want your electrical system to do. Myself and others have built boats where virtually all of the on-board electrical system is behind inverters. This includes clothes washers, electric clothes dryers, electric ovens, discharge and transfer pumps. Even HVAC. The goal is to be able to run loads without having to start a generator, run off batteries until they are low, then run a generator just long enough to recharge. Our overall usage is mixed, but we all do spend a lot of time at anchor for multiple days. These systems work really well, and give you a quiet ship for all but 2-3 hrs a day. I haven't had cause to try it myself, by my friends run HVAC in their staterooms through the night 100% on battery power. My wife and I really like cooking with gas so we have kept propane for our cooktop and outside grill, but others have converted these to electric as well. The only things I have that are not powered via the inverters are the hot water electric heating elements, and the shore power battery chargers.



I think these are the things you need to be asking yourself. Retrofitting a boat to do this can be difficult if not impossible, but with a new build it's pretty easy, so now's the time to think about it.


With a system like I describe above, LFP will quickly become a necessity. High capacity batteries will be needed, as will high charge and discharge rates. LA just don't work well for a system like this unless you seriously over size the batteries. The Peukert effect of large loads on LA is just too great, and the recharge times stretch out too long.


So first look at what you want your power system to do. Then look at how to do it.

Couldn't agree more. As I said, on a new build LFP makes sense.

 

[OldDan1943]

This all started when you asked for opinions and recommendations.
You have more opinions and recommendations than Carter has little liver pills.
Now, it is your boat, it is time for you to digest the opinions and recommendations and research, bite the bullet, digest the information, opinions and recommendations then, make your very own decision on your very own boat.
This discussion, as with many discussion, has turn into a circle. Make a decision so we can close this out and move on to things such as ..... heaven knows what.
I have a bit more requested information to provide and then, I will leave this forum so ya'll can continue with, opinion, recommendations and the ever famous 'My way is better than your way.'
A fruitful discussion would be, 1. this how I have done it. 2. the reasons behind my decision. Then I guess if you really wish, you can stretch it out to, 3. Now that I have learned, lived and experience my decision, this is how and why I wished I have done it.

I mean no disrespect to any of the knowledgeable people in this forum, but golly gee shucks, this poor horse needs to be buried.

 

[Simi 60]

I wouldn't ever use Rolls. And I wouldn't ever consider Chinese junk. And I don't care what you have. You have no idea of how long they will last.

Most if not all LFP cells are Chinese made.
I have found no evidence to suggest battleborn cells are any different

Cheap is cheap for a reason

.
Buying direct often saves vaste amounts of money
No shopfront, no sales team, no middlemen taking an endless cut.

If the EVE cells are good enough quality for Tesla to get involved with they are good enough for me.

You really need to do a bit of research and leave your "everything China bad" rhetoric where it belongs

 

[DDW]

As I have already said, for weekend or occasional users, LA batteries may be a better choice. You have to specify the use case. My understanding from the OPs other postings is this is a live aboard boat, not a marina queen.

Personally I will never use another FLA battery in my life as I am tired of the mess they make. So the choice for me is between premium AGM (Lifeline) or name brand LFP. I did an extensive spreadsheet of my options to replace, the cost for Lifelines was $5.53/useable AH, for Battleborn $11.86, for other (but still name brand) LFP $8.55. That is much less than your 4x difference. I still went with the Lifeline AGMs for reasons previously mentioned. If I spent most of the year on board instead of just 4-6 months, I'd have done the LFP.

 

[Mako]

Jeez, does every thread on TF become so heated??? I guess I need to cool things off, so let’s talk about anchors [emoji846]

 

[KnotYet]

And will you own the boat or even live long enough to break even on those fancy LFP batteries? And fire? If one of those LFPs gets going, abandon boat cuz you won't be able to squelch it. In short order, it may even burn its way through the bottom of the boat. Amuse yourself and Google electric car fires and how 10,000s of thousands of water hosed by firefighters does almost nothing to knock down the fire. With all of the angst boaters commonly have about unlikely catastrophes, like we MUST have dual Racors, this event, burning LFPs, is far more likely and potentially DEADLY to boot unlike having to change a filter in a pitching seaway. Yet, from the proponents of LFP technology I have seen ZERO concern or discussion or analysis or even rationalization.

If a FLA battery fails, remove it from the bank (or two if a 6-volt array) and carry on till you can get to a port and go to Costco or Sam's Club.

Most if not all LFP cells are Chinese made.
I have found no evidence to suggest battleborn cells are any different.
Buying direct often saves vaste amounts of money
No shopfront, no sales team, no middlemen taking an endless cut.

If the EVE cells are good enough quality for Tesla to get involved with they are good enough for me.

You really need to do a bit of research and leave your "everything China bad" rhetoric where it belongs

Give him time, maybe the tune will change again...

 

[OldDan1943]

Jeez, does every thread on TF become so heated??? I guess I need to cool things off, so let’s talk about anchors [emoji846]

LOL and then you talk about about 1 engine or 2 engines

 

[GoneDiving]

Buying direct often saves vaste amounts of money
No shopfront, no sales team, no middlemen taking an endless cut.

Buying direct also allows the end user to determine the level of complexity in the bank and control hardware. Often drop in units have to allow for the worst customer so include numerous features that may not be needed or wanted.

I can understand charter boats or others that need idiot proof systems but those with the slightest inkling can build and maintain a reliable system if all the fruit is left off.

At the end of the day we are talking about a battery not the space shuttle.

 

[Hippocampus]

Would point out
Lifelines can be easily equalized. Even their literature points this out and there’s no issue with off gassing.
Believe FLA is just too dangerous to be on any boat. Even for just coastal use. Beyond issues of knockdowns or spills even the remote possibility of a cracked case or any reason for loose acid wandering around is something I just don’t want to think about.
I lived with lifeline AGMs for 8 years on the hook. Think much of what’s stated about shore power intervals and use pattern is just not true in real life. Issue is how much and what form of alt. energy are you getting as well as where you are. Our batteries were on bulk for no more than a few minutes (never more than 5).
Agree with a well designed system the fire risk of LFP is negligible and that’s easily done in a new build. Just make sure your insurance company agrees.
Agree energy density is greater per weight and per space.
Rate of acceptance is a non issue if living on the hook off alt energy in my experience.
Don’t agree it’s the only way to skin the cat as presented by some here. Depending upon the design and use carbon foam or AGMs may still make better sense in both short jump coastal or off grid liveaboards.

 

[ksanders]

Would point out
Lifelines can be easily equalized. Even their literature points this out and there’s no issue with off gassing.
Believe FLA is just too dangerous to be on any boat. Even for just coastal use. Beyond issues of knockdowns or spills even the remote possibility of a cracked case or any reason for loose acid wandering around is something I just don’t want to think about.
I lived with lifeline AGMs for 8 years on the hook. Think much of what’s stated about shore power intervals and use pattern is just not true in real life. Issue is how much and what form of alt. energy are you getting as well as where you are. Our batteries were on bulk for no more than a few minutes (never more than 5).
Agree with a well designed system the fire risk of LFP is negligible and that’s easily done in a new build. Just make sure your insurance company agrees.
Agree energy density is greater per weight and per space.
Rate of acceptance is a non issue if living on the hook off alt energy in my experience.
Don’t agree it’s the only way to skin the cat as presented by some here. Depending upon the design and use carbon foam or AGMs may still make better sense in both short jump coastal or off grid liveaboards.

Really???

I'm sorry but that makes no sense at all to me.

FLA's too dangerous for use???

You do realize that FLA batteries have been, and are the primary means of energy storage in boats as long as we have had electricity on boats.

When you look over your harbor and see all the boats...

Every one of them probably has multiple FLA batteries.

 

[Codger2]

Discussion here at times feels like " I am not going to buy a car, those Ferraris and Rolls Royce are too expensive compared to my horse"

+1 That's where I'm coming from! If you are a classic car nut and have the financial where with all to buy one of the above, then go for it! While reading this entire thread again, it's pretty obvious that those who say they really don't need LFP batts for the boating they do are really referring to the cost! I'm a boat nut! If I was a car nut I would be driving a Rolls! Come on guys, lets call a spade a spade....I drive a Toyota by choice, not because of its cost.

 

[Hippocampus]

Have had one bad experience with FLA where the case broke as did battery box and another where acid spilled in a seaway. After that and looking at actual occasions where LFP caused safety issues . ‘Nuff said. Sure if you always boat in clement conditions and never are in large temperature variations no issues.. There’s a reason ABYC has a whole set of standards for placement and containment of FLA. the safety issues of FLA v LI are overblown. If anything in actual use think LFP comes out ahead.
Yes I realize FLA are ubiquitous. I also realize it’s best if there’s a bar going across the bank tightly screwed down to allow no movement or stout clamping on either side of each and boxes be thick grp structural strong enough to endure a strike from them if movement occurs. Further suggest venting protocols be followed and frequent periodic review of fastenings and integrity of containment occur. Think many folks look at their batteries upon launch or when troubles occur. Otherwise they’re on their own. Both occasions owner removed batteries for the winter. When reinstalled not secured properly. Other caps were not tighten.
With current boat prior owner used FLA for the windlass/ bow thruster. It’s in the master state room. It’s a ABYC violation to my understanding. It will be replaced.
Forget electric cars. Find a new car or truck sold in the last decade with FLA. don’t think that’s because of “maintenance free” issues. Boats get bounced around more than cars. Often get less attention.

 

[DDW]

Would point out
Lifelines can be easily equalized. Even their literature points this out and there’s no issue with off gassing.

Lifeline is pretty much the only AGM vendor allowing equalizing, and they do not suggest it be done routinely - only when your battery is already down on capacity and you are trying to salvage it. If you are depending on that to run them at PSOC, their life will be shortened. FLAs are often equalized aggressively every month in PSOC service.

I lived with lifeline AGMs for 8 years on the hook. Think much of what’s stated about shore power intervals and use pattern is just not true in real life. Issue is how much and what form of alt. energy are you getting as well as where you are. Our batteries were on bulk for no more than a few minutes (never more than 5).

"Bulk" is usually defined as the max current available phase, switching to "absorb" which is voltage limited. In European equipment they often do not make that artificial distinction. Good quality AGMs will accept as much as 0.8 - 1C for a little while if well down in SOC. If you have a source of charge sufficient to supply that, you will start in the absorb phase, skipping the bulk entirely. Lifelines for example have no charge current restriction, only voltage. That does very little to reduce the total charge time required to get to 100% though, because the acceptance rate will fall off from 80% to 100% SOC, which takes several hours no matter what your source of charge. More AGMs are murdered by ignoring this than any other cause. Rod Collins had a good write up on this along with discharge-charge tests demonstrating it. If you have a reasonable charge source, doubling the available charge current affects the full charge cycle time on LA batteries only a little bit. It may reduce the bulk phase from 30 to 15 minutes, but the absorb and finish take the same time regardless.

The big advantage of LFP isn't their charge acceptance rate (which is initially lower than AGMs), it is the lack of the LA charge tail and their indifference to PSOC operation.

 

[twistedtree]

LFP can accept much higher charge current than AGM - up to 5C. But for house batteries like those we are discussing this is limited by specification to a more stately 1C or less to reduce heat and associated wear on the battery. It’s really about the warranty more than anything. Absent BMS intervention, they will accept pretty much anything you can throw at them. Heating becomes the limiting factor

Very high AGM acceptance rate is really just a distraction. They can only do it for a very short period of time before voltage rises and it becomes self limiting. There is little to no practical value in it. Besides, who actually has charge capacity even as high at 1C, let alone 5C? It’s purely academic.

As for costs, if you are looking for the cheapest storage, it will be FLA, hands down. If you want more features and capabilities, it costs more for AGM, Carbon Foam, or LFP. So that’s the meaningful comparison rather than another academic one.

As for safety, I think AGM and LFP are about the same, and given the far less hazardous and toxic contents of LFP, I would give them the edge over AGM.

I think FLA is more hazardous simply because the contents are less contained, and there is the added explosion risk.

Non-LFP lithium-ion formulations I think have no place in a boat unless it’s a highly engineered system with containment, fire protection, etc as found in the couple of ferries where electric propulsion has been trialed. One of those ferries, by the way, had a battery system fire that was contained as designed, but burned for days if not weeks.

One thing that’s interesting to me is that we openly accept the risk of exploding, acid spewing, lead spewing FLA batteries. But a non toxic, smoldering LFP battery sends everyone into a panic. And all the other systems in our boats might have warning alarms, but none automatically shut down on their own to protect themselves. It’s left to the captain to decide whether something like an engine should be sacrificed for the safety of the ship. Yes with LFP we insist in automatic protections that protect the battery from damage, not just to provide safety. I think this is wrong, for the same reasons it’s not done with engines. A DC power system is a vital part of a boat, and loss of it presents a safety hazard. If keeping the batteries running aids the safety of the ship, even if it destroys the batteries, it’s the right decision to sacrifice them. I think automatic shutdowns should only protect against hazards, and should not simply protect the asset from damage.

 

[Mako]

One thing that’s interesting to me is that we openly accept the risk of exploding, acid spewing, lead spewing FLA batteries.

@TT, what scenarios would lead to catastrophic failure like that?

I’m aware of one which is most likely - the warnings about ganging FLA’s together. Everyone is so excited to use affordable Costco golf cart batteries (6V) ganged together in series/parallel.

But there is a real danger of fire in older banks where one cell dropping in performance, or going dead, will draw down a tremendous amount of amperes.

I’ve read that (for our typical pleasure boats) 12VDC electric is the #1 cause of fires, followed by 120VAC and then followed by propane gas far behind.

The safest way to connect FLA is purely in series. Example, 4 x golf carts for 24 volts. Or for more capacity then go 48 volts. Or best yet, go for industrial 2V batteries.

 

[DDW]

LFP can accept much higher charge current than AGM - up to 5C.

Very much dependent on the LFP. Some can, some can't without damage. Most can probably accept 1C, but many vendors limit to 0.5C if you want the warrantee. In packages solutions (e.g. Battleborn) the charge rate is limited by the BMS, usually to 0.5C. Victron specs their max recommended charge at 0.5C or less. Cells are made by the manufacturers with different goals, you can get high current cells if you order them, it isn't what you would ordinarily use in a house battery. You can get AGMs to charge at 2C, if you are willing to ignore the specs.

But I'd agree that charge acceptance much above 0.5C is irrelevant in house batteries. If I change out the AGMs in my sailboat to LFP though, I will have to turn the charge rate down - not up. In the trawler, I don't have enough alternator for it to be an issue, like most owners.