I want to replace the 200ah lead acid house battery in my 2005 Beneteau 423 with a 200ah lithium iron phosphate battery. I will keep the lead acid start battery. Can I simply replace the lead acid with the lithium iron phosphate, or are there additional changes that need to be made. I am aware of but not fully understanding that lead acid and lithium iron phosphate cannot be charged and/or used together. On the 423, the house and start batteries are wired together in ways I don’t fully understand. Just wondering how I need to configure all of these things correctly. My thought is that the charging should be separate and that the starting battery should only be for starting the engine. And the house should be for everything else. Two completely separate systems. Wanting to get it right. Thanks. -jeff
Lithium Iron Phosphate Battery
- Thread starter Jeff LeMunyon
- Start date
The link provided by James is excellent, in particular this article there - Drop-In LiFePo4- Be an Educated Consumer
At a minimum you’ll need how to best charge the lithium in a way that’s safe for your alternator. If you have a stock alternator that probably means having the alternator charge the start bank directly, then adding a DC-DC charger to charge the lithium. You’ll also want to make sure your shore charger has a profile for lithium.
At a minimum you’ll need how to best charge the lithium in a way that’s safe for your alternator. If you have a stock alternator that probably means having the alternator charge the start bank directly, then adding a DC-DC charger to charge the lithium. You’ll also want to make sure your shore charger has a profile for lithium.
I'm in the process of changing from LA to LFP batteries. A few general comments.
"Drop-In" LFP batteries are drop-in only in name and that name is misleading marketing hype. Drop-in LFP batteries typically have the same physical size as a standard marine battery (Group 27, 31 etc) and they have an internal BMS. Electrically they are very different animals from LA batteries.
There is no one right way to install a LFP battery, however, there are many really wrong ways and silly ways to do it.
The big advantage to LFP is the high charge acceptance rate and the ability to be deeply discharged without damaging the battery. They do this in a very lightweight package. Basically, you get more energy and more efficient charging in a lighter package. The 3 100 ah LFP batteries I'm installing weigh half what the 2 116 ah Firefly batteries weigh and I will get about a 50% increase in usable energy (180 ah vs 240 ah).
There are some drawbacks to LFP batteries. First, unlike LA batteries many of them are limited in how much energy they can deliver in a short period of time. This makes them unsuitable for brief high load uses, such as starting a diesel, operating a bow thruster, or a windlass. There are ways to get around this limitation, it is just not as easy as it is with a LA battery.
The charging profile is very specific to the battery. You must have a charger that can provide the correct charging profile and it should be large enough to take advantage of the high charge acceptance rate. Likewise, it is best to have an alternator and regulator that can adequately supply the battery and do so safely. Stock internally regulated alternators are not robust enough to charge LFP batteries, they will overheat and burn out.
The battery also has very specific fusing requirements. In normal operation the BMS keeps the battery from discharging too quickly, however, if the BMS fails in a short circuit it will dump an enormous current into the system, which requires a Class T fuse.
From my perspective, the silly way to install a LFP is often touted in the forums. In this method the alternator's output is directed to the LA start battery and the LFP bank is charged with a Battery to Battery (B2B, or DC-DC) charger. This protects the alternator because a LA battery has a limited charge acceptance rate and will keep the battery from overheating. This method is silly because the best feature of an LFP battery, high charge acceptance, is not used. Instead the LFP battery is charged at 30 amps regardless of the bank's size. This is no better than an AGM or FLA battery.
To install LFP and to gain the most benefit and avoid being wrong or silly you will need to consider at least:
FWIW, I am installing 3 100 ah Kilovault LFP batteries and one Mastervolt AGM start battery. Charging will be done with a ProNautic 50 amp charger on a custom setting, 300w Solar array with the controllers set to the LFP profile, and a 165a Balmar alternator with a Balmar 618 regulator. All charging sources will be lead to a charging busbar. The start battery will be maintained by a Victron DC-DC 18a charger. Each battery bank can be isolated with either one capable of supplying house loads. The BMS's on the Kilovault batteries are robust enough to supply starting power for the diesel or to operate the windlass. The whole system is monitored with a Bluetooth enabled SG200 and SmartShunt and the individual BT Victron chargers and controllers.
"Drop-In" LFP batteries are drop-in only in name and that name is misleading marketing hype. Drop-in LFP batteries typically have the same physical size as a standard marine battery (Group 27, 31 etc) and they have an internal BMS. Electrically they are very different animals from LA batteries.
There is no one right way to install a LFP battery, however, there are many really wrong ways and silly ways to do it.
The big advantage to LFP is the high charge acceptance rate and the ability to be deeply discharged without damaging the battery. They do this in a very lightweight package. Basically, you get more energy and more efficient charging in a lighter package. The 3 100 ah LFP batteries I'm installing weigh half what the 2 116 ah Firefly batteries weigh and I will get about a 50% increase in usable energy (180 ah vs 240 ah).
There are some drawbacks to LFP batteries. First, unlike LA batteries many of them are limited in how much energy they can deliver in a short period of time. This makes them unsuitable for brief high load uses, such as starting a diesel, operating a bow thruster, or a windlass. There are ways to get around this limitation, it is just not as easy as it is with a LA battery.
The charging profile is very specific to the battery. You must have a charger that can provide the correct charging profile and it should be large enough to take advantage of the high charge acceptance rate. Likewise, it is best to have an alternator and regulator that can adequately supply the battery and do so safely. Stock internally regulated alternators are not robust enough to charge LFP batteries, they will overheat and burn out.
The battery also has very specific fusing requirements. In normal operation the BMS keeps the battery from discharging too quickly, however, if the BMS fails in a short circuit it will dump an enormous current into the system, which requires a Class T fuse.
From my perspective, the silly way to install a LFP is often touted in the forums. In this method the alternator's output is directed to the LA start battery and the LFP bank is charged with a Battery to Battery (B2B, or DC-DC) charger. This protects the alternator because a LA battery has a limited charge acceptance rate and will keep the battery from overheating. This method is silly because the best feature of an LFP battery, high charge acceptance, is not used. Instead the LFP battery is charged at 30 amps regardless of the bank's size. This is no better than an AGM or FLA battery.
To install LFP and to gain the most benefit and avoid being wrong or silly you will need to consider at least:
- Installing a high output externally regulated alternator
- Installing a high output smart charger with LFP settings or custom settings
- Rewiring the main DC circuits to incorporate a Class T fuse
- Installing a B2B charger for the start battery
- Rewiring the DC circuits to allow isolation of the battery banks
FWIW, I am installing 3 100 ah Kilovault LFP batteries and one Mastervolt AGM start battery. Charging will be done with a ProNautic 50 amp charger on a custom setting, 300w Solar array with the controllers set to the LFP profile, and a 165a Balmar alternator with a Balmar 618 regulator. All charging sources will be lead to a charging busbar. The start battery will be maintained by a Victron DC-DC 18a charger. Each battery bank can be isolated with either one capable of supplying house loads. The BMS's on the Kilovault batteries are robust enough to supply starting power for the diesel or to operate the windlass. The whole system is monitored with a Bluetooth enabled SG200 and SmartShunt and the individual BT Victron chargers and controllers.
This may help:
Beneteau Wiring Diagrams - Maine Sail's corrections - Just in case you have a friend with a Beneteau and want to help him with his unusual switching Reply #8
One black and two red electrical switches
The advantage of the "silly way" is that it is considerably simpler and somewhat less expensive. It all comes down to how you use your boat.
If someone's cruising style would benefit from the expense of adding LFP batteries, then it makes sense build the system to take full advantage of LFP benefits, faster recharging, greater depth of discharge, and greater tolerance of PSOC or why else pay a premium for the batteries when AGMs would work as well for less money and even fewer modifications.
The difference in complexity between a direct the LFP charging system and using a LA battery as a buffer is minimal. Both methods require essentially the same components, proper circuit protection, proper charging sources, and a way to charge one bank from the other. Some of the components will differ however their functions will not. If by simple you mean the OEM alternator and dumb charger can be used with the silly system, then you are correct. However, your AGM and FLA batteries are not loving that system either and the ability to rapidly recharge the LFP batteries is lost. Second Star's alternator can comfortably output about 90a without over heating. From 0% SOC to 100% SOC it will take a little over 3 hours of running the motor. It will take 10 hours to do the same with a 30a DC-DC charger drawing from a LA battery. Attached is a copy of the basic schematic for my system, I think it is pretty simple.
It does make sense to go the "silly" way if this step is part of a multi-season plan to upgrade the electrical system to take full advantage of LFP batteries. This would be especially true if the current LA batteries were near or at end of life.
The silly way is only silly if you use your high output alternator as your main source for recharging. Many people are using solar as their primary charging source for house banks and the alternator is only for topping off the starting battery after starting. The B2B is only a backup system.
I agree. While is it nice to have the increase in capacity, if you cannot replace the Ah's used in a timely manner then you are wasting half of the potential. When I replaced my 210Ah 4D Lifeline which had a max daily usable capacity of about 150Ah (discharge to 20%SOC and recuarge to 90%SOC with my current 560Ah LFP which can do 90% SOC cycles without breaking a sweat I needed to up my charging game. I replaced the 15A shore charger with a pair of 30A sycronized chargers which can be fully programmed for all charging perameters. I also upgraded the controls on my voltage regulator (I already had a 108Ah externally regulated alternator with 30phase external regulator).
My upgrades included
- The means to limit the power output of the alternator to limit the heat buildup and prevent belt dusting.
- A means to shut off charging if the alternator case gets above a certain temperature.
- A dedicated exahast blower to remove excess heat produced by the alternator and lower the engine space temperature.
So yeah, more whoud be better. I have plans to change out my v-belt for a serpentine belt which will allow me to increase my alternator output from the current 60A to hopefully around 80A which would help a lot.
Now if I had solar, that would help a lot but at this time I have no good place to mount any panels on my 30' sailboat other than the top of the dodger and given the amount of shading that the boom does, that is not very effective. I am designing a full enclosure for my boat and the Bimini portion should allow me to mount 400-800 watts of panels which will go a long way to meeting my energy needs as long as the sun shines. Did I mention that I live in the Sunny Pacific Northwest?
Around here we have almost no wind in July and August so if you want to use your boat in the warm and almost always sunny summer months, you will be motoring a lot. The rest of the year we have plenty of wind to sail with but the sunny days are much less frequent. This makes solar a smaller payoff given that with good heating, you can sail 12-months of the year.
Last edited:
A long drive to and from the boat (still stuck on the hard because of a broken travel lift) on a drizzly afternoon provides time to contemplate. Let me clarify my earlier statements about a silly DC system.
The silliest system is one in which a lot of money is invested that does not match the intended use because it is too small or too large or any where in between. The DC system, storage, generation, and consumption should be tuned to the individual boater's needs and intended use.
There are two groups of sailors for whom charging the LFP bank via battery to battery charger might make sense.
As I mentioned earlier, if this is just a way point in a multi-season DC upgrade, it is a viable way to spread the cost over a couple of seasons while having a functional DC system.
During my contemplations I realized there is another small group of sailors for whom this system might make sense, those for whom a small 100 ah or less capacity is more than adequate and especially for those who have an antiquated shore powered charger. For these boaters the value of the increased life cycles maybe greater than the value of high charge acceptance rates. Recognize the cost of converting to a small LFP bank will approach $1,000. The best value in a 100ah LFP battery that I found was a Kilovault at just under $500. The Class T fuse holder and Fuse will set you back about $125 and a Victron 30 amp DC-DC charger will run about $275. That's $875 plus some extra odds and ends to actually install the system. Yes, cheaper poorly designed and manufactured stuff is out there, it won't find its way on my boat.
In my initial comments I was considering mostly cruisers who have moderately high energy (200-300ah) needs while on anchor or sailing longer distances. For this folks, charging a large LFP through a B2B charger from a LA battery is still a very silly idea.
The silliest system is one in which a lot of money is invested that does not match the intended use because it is too small or too large or any where in between. The DC system, storage, generation, and consumption should be tuned to the individual boater's needs and intended use.
There are two groups of sailors for whom charging the LFP bank via battery to battery charger might make sense.
As I mentioned earlier, if this is just a way point in a multi-season DC upgrade, it is a viable way to spread the cost over a couple of seasons while having a functional DC system.
During my contemplations I realized there is another small group of sailors for whom this system might make sense, those for whom a small 100 ah or less capacity is more than adequate and especially for those who have an antiquated shore powered charger. For these boaters the value of the increased life cycles maybe greater than the value of high charge acceptance rates. Recognize the cost of converting to a small LFP bank will approach $1,000. The best value in a 100ah LFP battery that I found was a Kilovault at just under $500. The Class T fuse holder and Fuse will set you back about $125 and a Victron 30 amp DC-DC charger will run about $275. That's $875 plus some extra odds and ends to actually install the system. Yes, cheaper poorly designed and manufactured stuff is out there, it won't find its way on my boat.
In my initial comments I was considering mostly cruisers who have moderately high energy (200-300ah) needs while on anchor or sailing longer distances. For this folks, charging a large LFP through a B2B charger from a LA battery is still a very silly idea.
I went for the "silly" method the first year of my lfp batteries. The next year I did the Balmar, serpentine belt, external regulator conversion. A cost savings that I hadn't considered was that the dc to dc charger installed the first year did not have to be removed as I only had to the settings and run the output leads to the agm start battery.
Disagree, we have 600 amph LIPO batteries and only a 20 amp DCDC charger from starter batt given the 60 amp standard alternator, plus solar. We have got rid of propane, run all electric appliances and have a electric dinghy outboard. We rarely go more than 3-4 days without plugging in, if anything we'd have to pump out before we'd have to charge....
How much solar do you have?
Edit: And how large is your charger? Is it connected to the start battery or directly to the LFP bank?
It just depends on why one decides to replace their Lead acid batteries. In my case, 3 years ago, I replaced two, worn out, 130 pound 4d, batteries with a couple of longer lasting 23 pound LiFePO4 batteries with much more usable capacity. I also might also add that the battery project entailed me having to clean up the sulfuric acid that the 4ds spilled into the battery box. I am so glad I will not need to do that again. I also understand that there will not be need to replace these LiFePO4 until after my sailing days are over with. The LiFePO4 batteries have a lifetime guaranty.
The question of how fast I can recharge them is not too important to me. It simply has never been an issue. My very silly system has worked great for me ever since.
The question of how fast I can recharge them is not too important to me. It simply has never been an issue. My very silly system has worked great for me ever since.
We have 400 watt solar, honestly it barely keeps up with fridge during a full day but it's flexible panels with super easy "install" so it is what it is.
We have a victron multiplus with 120 amp charger and 3kw inverter, each battery can take 50amp so a 150 would be better but it's a good unit, cost less than a high output alternator and does so much more.
The starter is only connected to the LFP with the DCDC charger at 20 amps. Alternator is standard 60amp so assuming 50% efficiency and 10 amp for misc I should be well safe of overload for it.
Thanks for the responses. Your solutions seem to be working for you and your sailing style.
While all DC systems have three components, storage, consumption, and generation, the relationship between those components are dynamic, vary one and it affects the others. I've thought about this a lot over the many (4) revisions of my DC System. The guiding light has been to install the most efficient system I can within my budget for our intended use, extended coastal cruising. Storage capacity and rapid charging are important characteristics for our system.
The new system consists of 300ah of LFP, 300w Solar, 165a alternator, and a 50a charger. The solar will generally meet our daily needs at anchor and come close to our daily needs while sailing. The larger alternator allows us to have a smaller battery bank because we can use the "excess" energy while running the diesel for other purposes to charge the batteries. And if it is necessary to run the diesel solely for charging, the run time is shorter. Our last system used the same charging components with 232 ah (160 ah usable) of Firefly batteries. They worked well for the year we were out sailing and met our needs, but could only sustain about 20 hours of sailing before needing to be charged again. The LFP batteries will give us about 50% more capacity which should get us sailing through the night and back in to daylight. The lower weight and increased life cycles are bonuses.
I hate to see people spend hard earned money foolishly. Batteries seem to be one area where this occurs a lot.
Absolutely agree, find what works for what you do.
Another bonus has been the information directly from batteries, which on ours has Bluetooth. The shunt measuring rarely match SOC on batteries and seeing individual battery status has been really good information. They also show temperature and stuff like that.
Truer words.......
Thanks for your great contributions to this thread. I'd rename it LiFePO4 "101"
Interesting video. I’m curious about the test conditions, specifically the condition of the battery before being punctured. He did say he had already shorted the leads in various ways. I’ve seen what that can do to a lead acid battery and I can confidently say it was more exciting than the aftermath he showed on the lithium. Also of note is that ABYC indicated they really couldn’t get something like that to happen in their testing - https://marinehowto.com/wp-content/uploads/2022/03/ABYC_LFP_Testing.pdfWe should all carefully consider our choices about batteries.
Simple is not a part of the LiFePO4 change from the Lead Acid batteries that were installed in our boats.
There was a steep learning curve, for most sailors, to get the lead acid batteries installed and the boat prepared to maintain the batteries, so we can optimize their usage.
The Lead Acid battery was invented in 1856. That is over 150 years of experience with the materials that make up the battery components.
I say this because the Lithium Ion battery is the new animal on the block. Sure they offer deeper charge density. But have you assessed the risks associated with this new technology. Is that Lithium battery a magical power source or a Pandora's box on your boat.
What happens if the LiFePO4 battery on your boat catches fire. What is your emergency plan? Oh but the manufacture says they are safe!
Check out this fun video.
Sure you would never drive a spike into the heart of your battery.
Or what about the fun facts surrounding this event
On July 11 2021, Morris Fire Chief Tracey Steffes announced that after nearly two weeks, the lithium battery fire which erupted on June 29 at a 70,000-square-foot warehouse in Morris, Illinois has been extinguished and is under control.
Morris Lithium Battery Fire Highlights Emergency Planning, Hazardous Chemical Management - VelocityEHS
The Morris battery fire was caused by a cascade of failures that not only initiated the fire, but created perfect conditions for it to quickly loose control.www.ehs.com
Get all the facts you can discover then make your choice wisely.
As for the Morris battery fire - that article says it involved lithium ion, generally less safe than lithium iron phosphate specifically.
Unfortunately, some of the information presented in the quoted post is misleading and irrelevant. When properly installed lithium iron phosphate (LiFePO4 or LFP) batteries are safe. In fact, even when abused they do not present a significant safety hazard.We should all carefully consider our choices about batteries.
Simple is not a part of the LiFePO4 change from the Lead Acid batteries that were installed in our boats.
There was a steep learning curve, for most sailors, to get the lead acid batteries installed and the boat prepared to maintain the batteries, so we can optimize their usage.
The Lead Acid battery was invented in 1856. That is over 150 years of experience with the materials that make up the battery components.
I say this because the Lithium Ion battery is the new animal on the block. Sure they offer deeper charge density. But have you assessed the risks associated with this new technology. Is that Lithium battery a magical power source or a Pandora's box on your boat.
What happens if the LiFePO4 battery on your boat catches fire. What is your emergency plan? Oh but the manufacture says they are safe!
Check out this fun video.
Sure you would never drive a spike into the heart of your battery.
Or what about the fun facts surrounding this event
On July 11 2021, Morris Fire Chief Tracey Steffes announced that after nearly two weeks, the lithium battery fire which erupted on June 29 at a 70,000-square-foot warehouse in Morris, Illinois has been extinguished and is under control.
Morris Lithium Battery Fire Highlights Emergency Planning, Hazardous Chemical Management - VelocityEHS
The Morris battery fire was caused by a cascade of failures that not only initiated the fire, but created perfect conditions for it to quickly loose control.
Get all the facts you can discover then make your choice wisely.
In the linked video a battery alleged to be a LFP battery is repeatedly hit with a large metal digging bar, eventually some smoke appears and after additional strikes with the bar flames appear. This kind of pseudoscience is a simply a distraction. What makes it pseudoscience? We can start with the absence of any any safety protocols even basic PPE. Then there is no a priori protocol guiding the "test," it is just whack it with a big metal pole to see what happens and then whack it again. In the video they state the battery has already been damaged by other "tests" they have conducted. To their credit, they do state they believe this fire is burning electrolyte and not the thermal run away fires other lithium chemistries are prone to. Ask yourself, how often are the batteries in your boat subject to the conditions depicted in the video?
The article about the lithium battery fire that went on for two weeks is simply irrelevant to a discussion about LFP batteries on boats. While the cause of the fire was not reported, it was reported lithium ion batteries were involved. Some lithium battery chemistries present a greater fire risk than LFP batteries which appear to have little to no risk of spontaneous fire. The source of this article should also be considered. It appears to part of a marketing effort and not legitimate journalism. (See the image of the page header below.) Clearly they are motivated to raise anxiety in order to sell their services.
ABYC has conducted extensive destructive testing of LFP batteries and not been able to set them on fire although by driving a couple nails into one battery they were able to get to smoke. ABYC is confident enough in LFP safety that they have issued standards for installation. Follow those standards and use appropriate equipment and you will be safe.
ABYC Ratifies E-13, their first lithium battery standard
The ABYC has ratified standard E-13 for lithium ion batteries on boats. Let's take a look at the standard and what it means for boaters.
panbo.com
And a real world example of what can happen when a LFP battery is over charged:
Solar Charge Controller Failures - Professional BoatBuilder Magazine
Solar charge controller failure can damage battery management systems. Informed choices and a sound installation help prevent problems
www.proboat.com
In the end it behooves all of us to vet our information sources before posting. Providing information of dubious provenance is a distraction from productive and informative discussion.