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Heads up - LiFePO4 and ABYC recommendations
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pcg



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PostPosted: Wed Oct 13, 2021 4:29 pm    Post subject: Heads up - LiFePO4 and ABYC recommendations Reply with quote

Yesterday I attended a Victron Energy Training Session. Most attendees were professional system installers (RVs or marine), but there were a few DIYers like myself in attendance. I learned from some of the installers that ABYC now (or will soon – I didn’t clarify that) requires that any LiFePO4 (LFP) battery on board a boat must have an EXTERNAL battery management system (with the exception of cell balancing circuitry).

I did a little research to verify this and came across this article … https://marinehowto.com/lifepo4-batteries-on-boats/. The author identifies himself as an active member of the American Boat and Yacht Council (ABYC) Li-ion Battery committee that is working on the safety standards for Li-Ion batteries. I won’t go into details about how this came about, the article does that, but apparently it has something to do with drop-in (complete internal BMS) LFP batteries designed to power street lights in a foreign country, that have internal contactors (used to disconnect charge and load currents) that are not adequate to handle current loads sometimes seen on boats. Some of these batteries have been repackaged and sold in the US under other names. I did verify that Victron Energy is NOT one of these. It is unfortunate though, as it is clear from Victron's data sheet, that their Li Superpack (internal BMS) battery can safely handle all currents that the battery would normally see on a small boat. They, and Battleborn, appear to be getting swept out with the bad guys.

If you’re curious about what a BMS for LFP batteries is required to do, here’s a summary of what I’ve learned. I found this topic a bit confusing at first and it took me awhile to feel like I somewhat get it, but if any of you have something to add or correct please do…

BMS requirements:
1) Cell balancing. All batteries that contain multiple cells assembled into one package (12v, 24V, etc.) have circuitry inside that enables cell balancing.
2) Load disconnect in the case of under voltage.
3) Charge current disconnect in the case of over voltage, high temperature, or low temperature.

The above are the fundamental requirements for a BMS. However, if the LFP is going to be on a boat, be aware that there are two additional requirements that may soon be (or are now) recommended by the ABYC:
1) There must be an alarm that warns the user before the BMS performs a load disconnect. This is to give the boat operator time to make adjustments and preparations for the disconnect.
2) The load disconnect and charge disconnect functions of the BMS must be performed external to the battery package. In other words, the battery package cannot be a drop-in battery – a battery with the complete BMS built into the battery package.

Prior to yesterday, I was planning on using a LFP with an internal BMS battery from Battleborn, Victron Energy, or Renogy, but am now planning on using a Victron Energy Smart Li battery, which does cell balancing internally, but the remainder of the BMS (load and charge disconnect) is done externally. Victron makes an array of products to do this, as there are a number of different ways it can be done, depending on what other components are in the specific design.

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pcg



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PostPosted: Wed Oct 13, 2021 5:18 pm    Post subject: Reply with quote

I want to emphasize that I don't have access to the ABYC recommendations, nor do I have a crystal ball into what they might do in the future. I'd sure like to hear any input from anyone else who has any more information they can add to the above. It seems a drop-in battery with a properly designed BMS (adequate for marine use) would be a benefit to everyone and something that major manufacturers (Victron, Battleborn, etc.) would be working hard to get approved by ABYC. I have to make a decision soon, so at the current time I'm erring on the side of caution and planning on a battery with an external BMS.
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kaelc



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PostPosted: Wed Oct 13, 2021 6:36 pm    Post subject: Reply with quote

What are you budgeting for your project? Victron batteries seem a little steep for my liking and I have been moving toward the the renogy dc-dc charger with mppt charging or a bluetti type generator.

Thanks for the update!
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thataway



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PostPosted: Wed Oct 13, 2021 8:15 pm    Post subject: Reply with quote

Thank you for the interesting update. I have not been able to find a free copy of the $50 Technical Information Report. (full standards cost $495, business membership is only $275.

From the Link to compass Marine:
Quote:
The ABYC Li-Ion Battery TE or “Technical Information Report” is finally published. It’s still a good distance out for this TE (technical information report) to become a full blown standard. ABYC standards often start as Technical Information Reports. A TE then eventually morphs to full standard status.


There is a Webnair by ABYC, along with the CEO of BattleBorn Batteries and Dragonfly Energy which references this technical bulletin.

I used Battleborn batteries and Victron Multiplus2000/80/50, which I believe qualifies as an external BMS. Also my DC to DC charging system also qualifies. I am not sure where all of this falls in with any Standards, at this time.

I had my Multiplus programed by Battleborn for my batteries. I feel this is important, and why one should go with the well known and reliable US battery builders. (Cells are made in China, as are most.)

When I had questions, I was referred directly to the engineers at Battleborn, or Victron.

But this information should discourage owners from not using the proper chargers

There are a lot of LiFePO4 batteries being put in boats and RV's today, without regard to any standards. People are charging off car or marine engines. There are risks to both the battery and the alternators.

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pcg



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PostPosted: Wed Oct 13, 2021 9:03 pm    Post subject: Reply with quote

thataway wrote:

I used Battleborn batteries and Victron Multiplus2000/80/50, which I believe qualifies as an external BMS. Also my DC to DC charging system also qualifies. I am not sure where all of this falls in with any Standards, at this time.

It sounds like you comply with what ABYC is contemplating, as the Multiplus products, when properly connected to a device that is monitoring the battery (in my case it's a VE.Bus BMS) and programmed, will shut off charging when required. This qualifies as external BMS. I'm using a DC to DC charger from Victron (Orion-TR) and its output must be connected to a relay that is controlled by the VE.Bus BMS, so that charging current can be disconnected if required.

According to Battleborn's website, all the batteries they now currently offer have a full BMS built-in. Same for Renogy. My understanding is that these batteries could then not be used on a boat.

thataway wrote:
People are charging off car or marine engines. There are risks to both the battery and the alternators.

Victron showed a setup at the training session that allowed for direct charging of a LiFePO4 battery from an alternator with this regulator installed...
http://www.c-brats.com/posting.php?mode=quote&p=360097
I didn't pay a lot of attention since that is not my application, but my recollection was that they were also incorporating a VE.Bus BMS. When someone asked how do you keep from damaging the alternator if the BMS suddenly disconnects the battery, they didn't have an answer.


Last edited by pcg on Wed Oct 13, 2021 9:11 pm; edited 1 time in total
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pcg



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PostPosted: Wed Oct 13, 2021 9:08 pm    Post subject: Reply with quote

kaelc wrote:
What are you budgeting for your project? Victron batteries seem a little steep for my liking and I have been moving toward the the renogy dc-dc charger with mppt charging or a bluetti type generator.

Thanks for the update!

I was contemplating Renogy as well, but if the above is true, their batteries will not meet future ABYC guidelines as they incorporate an internal BMS. An external BMS means that you will need a device that communicates with the battery, and will subsequently activate external relays to shut off any charging devices if over voltage, high temperature, or low temperature, is detected.
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thataway



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PostPosted: Wed Oct 13, 2021 9:47 pm    Post subject: Reply with quote

So you are saying that an internal BMS disqualifies a battery from being used in a marine application? I would would not have a LiFePO4 battery without an internal BMS. The external BMS is an additional safeguard. The two types of BMS give slightly different protection.

What am I missing?

From what I read on The Hull Truth is that many boats are using LiFePO4 batteries for tolling motors. Few if any of these are protected with an external BMS.

ABYC Standards are not law, but best practices. The Technical Information Bulletin is a prelude to establishing standards.

Thanks for any comments.
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pcg



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PostPosted: Thu Oct 14, 2021 12:07 am    Post subject: Reply with quote

thataway wrote:
So you are saying that an internal BMS disqualifies a battery from being used in a marine application? I would would not have a LiFePO4 battery without an internal BMS. The external BMS is an additional safeguard. The two types of BMS give slightly different protection.

What am I missing?
Thanks for any comments.

Part of the confusion comes from the non-standard definition of what a BMS should do, and what different manufacturers have provided for an internal BMS. All LiFePO4 batteries do some internal BMS, and that is cell balancing. I'm only passing on what I heard at the training session, and that is that ABYC is considering recommending (or may already have done so) that Li batteries have a BMS that does three things (as I outlined in my post above), and that of these three, only cell- balancing can be done internally. Batteries that are advertised as having a "complete internal BMS" and do all three internally do not meet the guidelines. An example of this kind of battery is the Victron Li Superpack which has internal contacts for disconnecting the load and charging devices. Other Victron batteries, such as the Smart Li battery, has separate communication cables for communicating voltage and temperature states to an external BMS, which then activates external relays.

The other two tasks - disconnecting the load when voltage falls too low, and disconnecting the charging devices when the voltage gets too high, or it gets too hot or too cold, MUST be done externally. This is to ensure that the contacting devices that turn the load and charging currents off and on are of suitable size to handle current loads that might be found on a boat.

Again, I'm just repeating what was being discussed. I was surprised, but glad I found out when I did, and thought I would pass it along. And perhaps what was being discussed is not correct, or will not happen. At any rate I am redesigning for external BMS. If I end up not needing it at least it has forced me to get a better understanding of what is required to properly manage a LiFePO4 battery.
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thataway



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PostPosted: Thu Oct 14, 2021 8:55 am    Post subject: Reply with quote

Yes, I understand that.

As I recollect that the Multiplus disconnects the load if voltage gets too high or too low. The DC to DC charger will not connect the load if voltage is too low, and will disconnect if too high. Both of these chargers will disconnect if the is too hot.
I believe that an external high loaded inverter or charger should have a temperature lead to the battery.

This does leave the wiring between the chargers and the battery only protected by the internal BMS. The only issue then remains if the output to the 12V (actually 13.26 volts) circuit--in the boat I sold, Is only the freezer and refrigerator circuit is too low a voltage--which is handled by the internal BMS.

Since the Battleborn (and a few other batteries) have robust internal BMS, it would seem not at risk....Or I am still missing something. I'll have to go over that video with the CEO of Battleborn again--and see if there is something there. Also the internal BMS balance the cells, which an external cannot do.

Also Will Prowse videos contain a wealth of information on BMS and LiFePO4 batteries, granted he deals mostly with land or RV based applications:

From the How to Marine site:


Quote:
Unfortunately these FET’s often can’t handle the typical loads imparted by many cruising boats. On board devices such as bow thrusters 400A +, windlass’ (100A to 300A+, large inverters 150A to 300A +, electric winches 75A to 300A +, electric cook tops, massive alternators, chargers or large inverter-chargers are very very common on-board cruising boats these days. These are exactly the devices many boat owners are hoping to see a gain in performance from when switching to LiFePO4.

This is what a 120A rated FET based BMS, one of the biggest currently available, internal FET based BMS boards typically looks like with the heat sinks removed. The blue wires connect to the neg end of the cell string and the black wires are connected to the external negative battery post. This one uses two 10GA wires for its 120A continuous rating. All 120A has to pass through those two 10AWG wires, the printed circuit board and the FET’s. The hotter FET’s run the shorter the MTBF (mean time between failure) is.



My recollection is that the Battleborn batteries uses a bus bar to the output from internal BMS.
Since the only high loads are going thru the Victron inverter (and another good reason to use Victron or Mastervolt inverters) which has an external BMS, the batteries seem to be protected.

The largest load would be about 130 amps with the microwave. This is shared between the two Battleborn batteries, or 65 amps per battery.

This type of issue is why I suggest that people not just throw in a li battery and charge from an outboard or vehicle without any over voltage or temperature protection.

Incidentally the Li battery output goes directly to a 500 amp rated switch, via about 6" of 2/00 wire. Next about 3" away is a 300 amp fuse. Short distances, large cables are imperative with these high capacity batteries.

Maybe my 85 year old brain is missing something.

Thanks


Last edited by thataway on Thu Oct 14, 2021 9:14 am; edited 1 time in total
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kaelc



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PostPosted: Thu Oct 14, 2021 9:08 am    Post subject: Reply with quote

From my recollection C-dory’s were not built to ABYC standards until a few years ago, so let’s take the recommendations and use our best judgement on how to implement them.
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pcg



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PostPosted: Thu Oct 14, 2021 9:52 am    Post subject: Reply with quote

kaelc wrote:
From my recollection C-dory’s were not built to ABYC standards until a few years ago, so let’s take the recommendations and use our best judgement on how to implement them.


Yes, I agree, and I certainly didn't intend to alarm anyone. I just wanted to make folks who are contemplating LFP aware of this issue. My situation is different than most in that I'm building out a boat from a bare hull and I want to make sure I can get insurance. I'm insured now, but only for storage, not for on the water. I'm aware that, in some instances, lack of conformity to ABYC guidelines can be an argument for an insurance company to deny coverage so I'm not just concerned about reliability and safety, but also the perception of reliability and safety.
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PostPosted: Thu Oct 14, 2021 10:42 am    Post subject: Reply with quote

My plan is to use Battleborns. They're one of the best batteries on the market with an internal BMS disconnect for low and high voltages. One of the most advanced batteries, warranties and built right here in the US. If I go to sell and the buyer doesn't like them I'll gladly take them out and put in lead acid. Smile
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san juanderer



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PostPosted: Thu Oct 14, 2021 11:01 am    Post subject: Reply with quote

When some see the LI battery, they just see the external case and posts. Looks like a wet cell or AGM battery. But the picture above reveals that current flows thru two 10 guage wires. In your home a 30 amp circuit uses a 10 guage wire.
Do the math.
Now those 2 wires are very short, so the tables regarding ratings might be underrated. But how much ?
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thataway



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PostPosted: Thu Oct 14, 2021 12:47 pm    Post subject: Reply with quote

The teardown of the Battle Born is very instructive. It uses sold copper from cells to posts. The BMS is in the negative circuit, and input/out put are 5# 10 wires, which will easily handle 100 amps discharge or charge. It uses cylindrical cells. Current cost is $799.

Will Prowse tear down of the Battle Born 100 amp hour battery

I have used a Renogy 100 amp battery which uses packet cells, and a slightly little less robust conductive mechanism, with 4 wires from the BMS to the terminal posts. Will Prowse tear down of Renogy. These are now down to $600, and become very competitive with AGM batteries.

Caution: many of these are not certified for engine start batteries--so total conversion is not wise unless you have high confidence that the system you use will be able to used for engine start without damaging the battery.

As to the issue of building to ABYC Standards--my recollection is that most C Dorys I have seen are in compliance with ABYC when leaving the factory. Modifications can be in violation of the standards. ABYC does not certify boats.

What has happened in more recent years is that C Dory has built some boats to CE standards. There inspections have to be made that the boat meets the EU standards. The boat cannot be sold as new unless it meets the CE standards.

Quote:
Recreational Craft Directive (RCD), which is a single set of “harmonized” essential requirements for boats sold in any member country. Unlike the ABYC standards in the US, compliance with the RCD is required by law in the EU and third-party inspections and certifications are required as part of the process. The boat is given a CE mark at the end of the process, which confirms that it has passed muster and is legally valid for sale in the EU. These are typically referred to as “CE boats.”
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Pat Anderson



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PostPosted: Thu Oct 14, 2021 6:28 pm    Post subject: Reply with quote

This is all way beyond my comprehension. All the batteries we have right now are NAPA flooded cell deep cycle batteries. I would like to get lithium ion batteries for both the boat house batteries and the Northern Lite camper, but I have read quite a few articles on charging them and am more confused than before. On my chargers I do not have the option to set different voltages for different charging stages, and I don't understand what you do when you have lithium house batteries and a flooded cell or AGM starting battery. It does not seem that they can both be connected to the same charger (?) - and can they both connect to the outboard's alternator with the VSR, or would I need a ton of other stuff to regulate the lithium ion battery's charging? So I guess for now I will stick with flooded cell and replace with AGM when needed.

I applaud Dr. Bob for going down this path - I'll be he buys green bananas too!

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