Battery: Firefly Carbon Foam
- Thread starter xavpil
- Start date
You take the batteries to the local scrap metal dealer so they can be recycled. That's what I did.
Firefly batteries were a great innovation and ticked all the boxes for the cruising sailor, good low SOC tolerance, high charge acceptance rate, less expensive than LiFePO4 batteries. They were an affordable option for cruising sailors instead of lithium batteries.
I had 2 of them and they met all expectations for the year I spent cruising. They were frequently deeply discharged and recharged with a high output alternator. They were everything I expected. Then I returned home and had the boat on shore power and gradually over the summer they did not seem to hold their charge as well, or perhaps more accurately the batteries capacity declined rapidly. I was not alone in experiencing this.
The batteries were originally designed for the trucking industry to meet the needs of long distance truckers who needed good batteries to run everything while they were in the mandatory resting periods. The batteries could be drawn down to a low SOC overnight and still be able to start the diesel in the morning. They could also accept a high charge, as much as 40- 50 amps, so they would recharge while on the road.
Eventually the company was sold and production was moved overseas. This did not work out well. There were production and warrantee problems and eventually the company ceased production.
There is one shred of (sort of) good news in this story. If the batteries were installed correctly, with a high capacity alternator and a high capacity charger most of the work to transition to LiFePO4 has been done.
All of this is well documented on YouTube and especially in Cruisers Forum.
Firefly batteries were a great innovation and ticked all the boxes for the cruising sailor, good low SOC tolerance, high charge acceptance rate, less expensive than LiFePO4 batteries. They were an affordable option for cruising sailors instead of lithium batteries.
I had 2 of them and they met all expectations for the year I spent cruising. They were frequently deeply discharged and recharged with a high output alternator. They were everything I expected. Then I returned home and had the boat on shore power and gradually over the summer they did not seem to hold their charge as well, or perhaps more accurately the batteries capacity declined rapidly. I was not alone in experiencing this.
The batteries were originally designed for the trucking industry to meet the needs of long distance truckers who needed good batteries to run everything while they were in the mandatory resting periods. The batteries could be drawn down to a low SOC overnight and still be able to start the diesel in the morning. They could also accept a high charge, as much as 40- 50 amps, so they would recharge while on the road.
Eventually the company was sold and production was moved overseas. This did not work out well. There were production and warrantee problems and eventually the company ceased production.
There is one shred of (sort of) good news in this story. If the batteries were installed correctly, with a high capacity alternator and a high capacity charger most of the work to transition to LiFePO4 has been done.
All of this is well documented on YouTube and especially in Cruisers Forum.
Yes. They are not reliable. I know you are planning a long cruise, I would not trust them for that. If next season you will be mostly in and around the marina, then you could get a way with another season.
As for winterizing them, there is really nothing to do. They should be no worse than they are now next spring.
The problem is they will suddenly fail to hold a usable charge. This is unlike other LA batteries where the capacity gradually declines over time.
Yes I am planning on a long cruise: winter in the Bahamas...
Now, I am sorta okay to buy lithium because I understand that I need reliable elements on the boat.
But now that "everybody" seems to be making lithium battery.... which direction to go?...
I checked the LiFePO4. What makes them good vs others... I don't know.
I don't even know what specs to look for
I bought the boat last August and the previous owner "thought" they were one year old...
Two already had this green powder corrosion showing.
The most important thing to know is "drop-in lithium batteries are only drop in in size."Yes I am planning on a long cruise: winter in the Bahamas...
Now, I am sorta okay to buy lithium because I understand that I need reliable elements on the boat.
But now that "everybody" seems to be making lithium battery.... which direction to go?...
I checked the LiFePO4. What makes them good vs others... I don't know.
I don't even know what specs to look for
There is a lot to learn and know about using Lithium batteries. Start with this article.
Drop-In LiFePo4- Be an Educated Consumer
Lead is Dead (almost) Warning: This article is long and detailed. It may require two reads so the nuances and detail are not missed. You may be wondering why I am saying lead is dead ?The answer to that is simple; lead acid battery makers dug their own graves
marinehowto.com
will do thx!. Start with this article.
Drop-In LiFePo4- Be an Educated Consumer
Lead is Dead (almost) Warning: This article is long and detailed. It may require two reads so the nuances and detail are not missed. You may be wondering why I am saying lead is dead ?The answer to that is simple; lead acid battery makers dug their own gravesmarinehowto.com
Maine Sails article is a great source of info. Many of us have converted to LFP (LiFePo4) batteries which I consider to be the only good lithium chemistry for a boat. It does not have the explosive and fire risks that the other types do. Two years ago, I built a DYI LFP battery on my boat that has 560Ah of capacity which fits into a compartment built for two Group 27 batteries. I can use 500Ah without ever worrying about degrading them and they should last for much longer than any other battery I have ever owned.
The two main things to consider in the charge is your battery charger and alternator. Maine goes into a lot of detail on these things. What do you have for battery charging and is your alternator the factory internally regulated type or a high output externally regulated one.
Back to your original question on the Firefly's, If they still hold a charge, and you want to nurse another season out of them, they get winterized like any other lead acid battery. Charge them fully and disconnect them and store them. Give that you are in Milwaukee, they would be best stored in your home garage. As long as they are fully charged, they will not freeze down to around 0ºF but you can get much colder than that.
I thought a fully charged battery was good to about -70F. ( Helping Your Boat Battery Survive Winter Storage - Practical Sailor )
One of the promises of Firefly batteries was the ability to be left in a partial state of charge for extended periods with losing capacity. The early batteries met that promise.
A Firefly battery is an AGM battery with a carbon foam mat instead of a glass mat. There is (was) a video floating around on the internet by Nigel Calder in which he speculates that the small cell structure of the carbon foam inhibits the formation of large sulfate crystals. The smaller crystals are easier to break up and do not expand as much as larger crystals in glass mat and FLA batteries. Thus the capacity does not change when left in a PSOC.
Because the Fireflys tolerate being in PSOC far better than traditional AGM or FLA batteries, they do not have to be returned to a fully charged condition before winter storage, although it is still a good idea. As @Davidasailor26 notes, LA batteries have a very low freeze temperature, if they are fully charged. Leaving the batteries fully charged in the boat over winter is fine. There is often concern about the self-discharge rate of extended storage which lowers the SOC and potentially reduces capacity. This concern is often over stated. Batteries generate electricity through a chemical reaction. One of the basic tenets of chemistry is cold slows chemical reactions. Thus over winter the colder the better as the reactions slow and the self discharge rate is thereby reduced.
In Michigan, fully charged batteries that are disconnected can be safely left in the boat. My boat is in Upstate NY with winter temperatures below freezing for weeks at a time. My batteries have always been left in the boat with no appreciable deterioration in performance. My back appreciates not moving 70 lbs batteries around twice a year.
A Firefly battery is an AGM battery with a carbon foam mat instead of a glass mat. There is (was) a video floating around on the internet by Nigel Calder in which he speculates that the small cell structure of the carbon foam inhibits the formation of large sulfate crystals. The smaller crystals are easier to break up and do not expand as much as larger crystals in glass mat and FLA batteries. Thus the capacity does not change when left in a PSOC.
Because the Fireflys tolerate being in PSOC far better than traditional AGM or FLA batteries, they do not have to be returned to a fully charged condition before winter storage, although it is still a good idea. As @Davidasailor26 notes, LA batteries have a very low freeze temperature, if they are fully charged. Leaving the batteries fully charged in the boat over winter is fine. There is often concern about the self-discharge rate of extended storage which lowers the SOC and potentially reduces capacity. This concern is often over stated. Batteries generate electricity through a chemical reaction. One of the basic tenets of chemistry is cold slows chemical reactions. Thus over winter the colder the better as the reactions slow and the self discharge rate is thereby reduced.
In Michigan, fully charged batteries that are disconnected can be safely left in the boat. My boat is in Upstate NY with winter temperatures below freezing for weeks at a time. My batteries have always been left in the boat with no appreciable deterioration in performance. My back appreciates not moving 70 lbs batteries around twice a year.
Fully charged, yes. Fully discharged it will freeze at 32º. Given self-discharge over time, during the coldest time of the winter, it will be somewhere between the two. I was being cautiously conservative.
With all due respect, this goes against the fundamental chemical process inherent in lead acid battery chemistry.
Potentially it is less noticable, and the smaller crystals may not cause the mechanical damage that the larger crystals may cause, however, the fundamental chemistry is the same. Lead sulfate does not break down into lead and sulfur at charging voltages, that's what equalization voltages achieve.
It's possible that you can allow more sulfation to occur and still be able to equalize to remove it, I don't know. In standard deep cycle batteries the lead sulfates can get buried too deeply into the lead on the plates such that equalization cannot break it back down. But when the lead is tied up in lead sulfate, it is removed from the battery capacity, hence battery capacity must be lowered.
dj
I second that emotion. Great promise; but after two batteries being replaced under warranty after one season I was offered a deal by the US importer to replace all with their high end AGM batteries at cost and I'm glad I did. Sold that boat afterward and bought one with a properly installed LiFePo4 system installed and it is awesome.
The Firefly manual makes no reference to an "equalization" charge. They do call for periodic restoration charges which are high current charges, followed by a deep discharge. From the manual:
The recommended charging current is .4C to .5C @14.4v, which is about 45 amps per battery. As for breaking the ionic bonds in the sulfate crystals, I draw a parallel to salt. Finely ground salt dissolves into solution more quickly than large crystals. Admittedly it takes more energy to break the bonds in lead sulfate than salt, however, it is difficult for me to see how that basic principle we see in salt would not apply to lead sulfate, smaller crystals are easier to put in solution than larger crystals.
High equalization voltages in FLA batteries are needed to mix the electrolyte as it will stratify with a higher concentration of sulfuric acid at the bottom than the top of the battery. The high voltage is necessary to cause convection currents to mix the water and sulfuric acid. An AGM battery like the Firefly does not have the same level of stratification as a FLA battery and the sulfate crystals do not settle to the bottom of the battery case. Thus, destratifying the electrolyte is unnecessary.
As I understand equalization charging of an FLA battery it is done at the .2C rate at ~15v. For a 100 ah battery that is 300 watts (20a * 15v). The normal charging condition for a Firefly is 14.4v at .4C, the battery is charged at 669 watts (46a @ 14.4). This is more than twice the energy provided in the equalization phase of a FLA battery.
If this is all correct, then it explains why an equalization charge is not needed and why repeated shallow charging is deadly to FF batteries. Functionally, every charge cycle at the recommended current is in essence an equalization charge. Lower charge currents supply much less power than the typical FLA charge current, i.e., 20a @ 14.4v (288w) vs. 20a @ 14.8v (296w). Without the high current charge the sulfate crystals build up in the foam, reducing the batteries capacity.
Of course, all of this is kind of moot since FF batteries are no more.
The normal equalization voltage for a flooded lead acid battery is 15.8 to 16.2 volts. Decimals matter.
Lifeline AGM's are the only AGM battery that publish an equalization cycle for AGM's as far as I'm aware. It falls within the above, although it isn't exactly the same. I used to have Lifelines and would do their recommended equalization but I don't recall the exact potentials they publish.
The current must be controlled to limit heating. So it is not the over-all energy being put in, but rather you have to cross the threshold in potential to break down the lead sulfate bonds.
The stratification you talk about above is primarily for stationary battery banks. Boats are not stationary so it's not as much of a problem. (I guess dock queens could be an exception)
I have seen the 15v referenced - as far as I'm aware it is simply wrong. You can look this up in an IEEE standard. I don't recall the number off the top of my head or I'd give you the citation.
But as you say, it's beating a dead horse as these batteries are defunct.
dj
Lifeline AGM's are the only AGM battery that publish an equalization cycle for AGM's as far as I'm aware. It falls within the above, although it isn't exactly the same. I used to have Lifelines and would do their recommended equalization but I don't recall the exact potentials they publish.
The current must be controlled to limit heating. So it is not the over-all energy being put in, but rather you have to cross the threshold in potential to break down the lead sulfate bonds.
The stratification you talk about above is primarily for stationary battery banks. Boats are not stationary so it's not as much of a problem. (I guess dock queens could be an exception)
I have seen the 15v referenced - as far as I'm aware it is simply wrong. You can look this up in an IEEE standard. I don't recall the number off the top of my head or I'd give you the citation.
But as you say, it's beating a dead horse as these batteries are defunct.
dj
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On the other hand, thinking about and discussing sometimes arcane aspects of sailing and cruising helps us to better understand the systems on our boats.
For a more pressing topic, how do I find and get rid those people who keep hiding stuff on my boat? It is really getting annoying. I know it's neither my wife nor I who would do such a thing. Boat projects would go more quickly if only these denizens would cease with their antics every time I turn my back.
