LiFePo or Carbon Foam AGM

[OceanPlanet]

if only I were able to make those decisions...sigh.

However one wish is done: there is no need to "equalize" Firefly CF batteries. That is a desulfating survival technique for other Pb batteries that can suffer permanent sulfation. Which doesn't happen with Firefly. Simply do a full charge & discharge cycle, recharge and good to go.

Originally Posted by ranger42c

And remember that 6V golf cart version, please. (Perhaps ideally, equalizable, like Lifelines.)




I'd be an early adopter, but for that G31-only thing... and I might be due to replace our oldest bank of Odyssey G31s next season.

-Chris

[Maine Sail]

Originally Posted by ranger42c

And remember that 6V golf cart version, please. (Perhaps ideally, equalizable, like Lifelines.)

As Bruce said these batteries do not need equalization and it is actually counter productive. They recover lost capacity due to sulfation through one or two back to back deep discharges, each one followed by full recharges to 100% SOC at 14.4V temp compensated to 77F. At the worst you may want to hold them at 14.4V a bit longer than normal.

I was very skeptical of the technology when Bruce first showed it to me, so I bought one and began beating the living piss out of it. I could not make it lose capacity and even left it sitting in my shop for about 40 days at about 35% SOC, and it recovered fully. (this was an accident not on purpose BTW)

At that point I was very intrigued and wanted to see how it would compare to other competitive AGM's including some others that claim sulfation resistance. I then set up and conducted PSOC AGM testing with competitive batteries, which involved hundreds and hundreds of hours of data collection, and cycling and the Firefly nailed that too...

Yes they have growing pains and that is a bit frustrating but I hope it can grow because the technology for resisting sulfation build up actually works.

I do have one on my own boat as a reserve lead bank. It has been charged at 13.8V and I capacity tested it last week and it is still producing 100% of its capacity. It really does seem to pair up well as a reserve battery for LiFePO4 even when charged at just 13.8V as opposed to 14.4V. Course I only cycled it a few times over the season using the inverter but still, it has only been charged to 13.8V. This type of charging would permanently damage other AGM's...

I do have a real market and a definite need for these batteries, for my own customers, but supply has been hard to get. Hopefully I can get some inside scoop today about future production.

Keep in mind these are not LiFePO4 they are still lead acid but with a much higher resistance to sulfation and a deeper cycling ability. They match up very well to PSOC use, how we use batteries on boats, but are still not LFP in terms of overall performance.

They should also be treated like any expensive battery with temp compensated charging, good quality charge sources, large alternator, alternator temp compensation etc...

[ranger58sb]

Originally Posted by OceanPlanet

However one wish is done: there is no need to "equalize" Firefly CF batteries. That is a desulfating survival technique for other Pb batteries that can suffer permanent sulfation. Which doesn't happen with Firefly. Simply do a full charge & discharge cycle, recharge and good to go.

Originally Posted by Maine Sail

As Bruce said these batteries do not need equalization and it is actually counter productive. They recover lost capacity due to sulfation through one or two back to back deep discharges, each one followed by full recharges to 100% SOC at 14.4V temp compensated to 77F. At the worst you may want to hold them at 14.4V a bit longer than normal.

Good to know, thanks for clarifying that!

-Chris

[exMaggieDrum]

Bruce (at Ocean Planet)
Thanks for all the contributions to the forum. I just did a quick and dirty (but a long couple of hours) search to find out availability and pricing of the G31 batteries from Firefly. Some other posts here imply they are hard to buy. Are they currently available to ship and what is the cost of them?

Also, Maine Sail said something to the effect that the carbon Fireflies are still basically LA AGMs with some new tech. I have read that they can take up to 250A of charge at 25C. But other AGMs can take that current and then closer to 90% SOC start pushing back so cannot sustain that current. From what is said on here that is OK since you don't have to bring them up to 100% SOC like you do other AGMs to maintain capacity over many cycles. Can you provide any info on the charging characteristics of the Fireflies?

[OceanPlanet]

Yes, they are available. There was a big backlog over the summer however now they are more caught up. We have a good inventory here in Maine, NorCal, SoCal, and some in Seattle but not sure how many are there. Check with BRJ Solutions there.

Regarding charging, like all AGM's the CAR (Charge Acceptance Rate) is good when you star from a low SOC, but of course the CAR gets lower and lower at higher SOC. However the big difference with the carbon foam AGM is that you don't have to do the long slow absorption charge...simply don't bother to charge to 100%. Every now & then it is a good thing to do but it's not mandatory as with other AGM.

So, you can use discharge them deeper, then recharge fast with a high-output alternator (etc.) to 14.4V. And when the CAR slows down to the point where you feel like you are wasting fuel simply stop charging. If you have charge sources that will stay on (solar, wind, shore, or motoring for a long time) you should adjust the float voltage to 13.2V or less. No need to hold them higher than that once they have been charged; and in fact they will last even longer this way.


I hope this helps!
B

Originally Posted by exMaggieDrum

Bruce (at Ocean Planet)
Thanks for all the contributions to the forum. I just did a quick and dirty (but a long couple of hours) search to find out availability and pricing of the G31 batteries from Firefly. Some other posts here imply they are hard to buy. Are they currently available to ship and what is the cost of them?


Also, Maine Sail said something to the effect that the carbon Fireflies are still basically LA AGMs with some new tech. I have read that they can take up to 250A of charge at 25C. But other AGMs can take that current and then closer to 90% SOC start pushing back so cannot sustain that current. From what is said on here that is OK since you don't have to bring them up to 100% SOC like you do other AGMs to maintain capacity over many cycles. Can you provide any info on the charging characteristics of the Fireflies?

[zboss]

Originally Posted by OceanPlanet

Simply do a full charge & discharge cycle, recharge and good to go.

What specifically IS a full discharge on the Firefly batteries?

BTW - I see they make 4 V E31 batteries. Any take on them?

[Ostinato]

Does anyone know if Firefly batteries (E31) are available in Europe?

[exMaggieDrum]

Bruce, thanks for the reply regarding charging. Prices? I'll call your Seattle distributor.

Regarding the questions on the E31 batteries, I had not really checked that out (and should have). There must be a configuration difference of some sort between the E31 (4V and 12V) and the G31 but I can't find any reference to a group E31 anywhere. The H W L is identical for all three batteries. Weight and terminal specs are the same too. What's the difference?

The two 12V batteries (E31 and G31) have identical Ah ratings (e.g. 116Ah @ 20hrs) but the 4V battery has a whopping 346Ah!!! Could you confirm that please. Since the nominal voltage is 4V (versus 3.2 for the LFP smaller batteries), does it take only 3 batteries in series to make a nominal 12V (seems it should)? For 1038Ah!! in three batteries the size of a G31. Amazing. I also noted that the max charge for the 4V batt is 150A while the max charge rate for the 12V batteries is 250A.

Could you comment on these points please?

[Maine Sail]

Originally Posted by exMaggieDrum

Bruce, thanks for the reply regarding charging. Prices? I'll call your Seattle distributor.

Regarding the questions on the E31 batteries, I had not really checked that out (and should have). There must be a configuration difference of some sort between the E31 (4V and 12V) and the G31 but I can't find any reference to a group E31 anywhere. The H W L is identical for all three batteries. Weight and terminal specs are the same too. What's the difference?

The two 12V batteries (E31 and G31) have identical Ah ratings (e.g. 116Ah @ 20hrs) but the 4V battery has a whopping 346Ah!!! Could you confirm that please. Since the nominal voltage is 4V (versus 3.2 for the LFP smaller batteries), does it take only 3 batteries in series to make a nominal 12V (seems it should)? For 1038Ah!! in three batteries the size of a G31. Amazing. I also noted that the max charge for the 4V batt is 150A while the max charge rate for the 12V batteries is 250A.

Could you comment on these points please?

In series Ah capacity stays the same.... So three 4V batteries in series is still 346Ah bank or about the same Ah capacity as three 12V G-31 Firefly batteries. The 4V batteries may use thicker cells, because only 2 cells need to fit in a G31 case, vs. 6 cells, so the benefit may be in higher cycling life.

The magic of a Firefly not necessarily in its AGM acceptance rates but rather that you can cycle in bulk (bulk is nearly 100% efficient) many more times in between 100% recharges than you can with other AGM batteries.

If this cycling is from say 20% SOC to 80% SOC you are really using 60% of the banks capacity vs. traditional AGM's where you would cycle from 50% to 80% & use about 30% of the banks total capacity. Course this type of PSOC use would sulfate and damage a traditional AGM where a Firefly AGM could recover this lost capacity to go on and do another 20 -30 days between full recharges.

I would not concern yourself with max charge rates between any of the AGM's once you get above about .5C, as these are still lead acid AGM batteries and like any AGM they will take what they take until they become voltage limited.

The higher the current the sooner in the SOC curve you hit absorption voltage (constant voltage) and begin limited current acceptance. The lower the current the later in the SOC curve you hit acceptance limits. AGM's can benefit from higher charge currents but really there is a point at which throwing more at them means a less charge efficient cycle as you will just be in absorption the entire time.

This chart by Lifeline shows that by throwing more current at the battery the high current does not last very long. At 2C or 200% of Ah capacity bulk is over pretty much instantly.

Where this chart fails us is that it does not take the time to 100% SOC into account, it stops at 2 hours, so it is a bit misleading in that regard. The differences in time to 100% SOC would not be as different as many often assume they are. This time to 100% SOC is where a LiFePO4 battery slam-dunks an AGM battery yet a LiEPo4 never needs to even get there and an AGM, especially traditional AGM's, need to....

No AGM battery I know of is going to take 2C or let alone .5C all the way to 90% SOC especially if starting from 50% SOC. By the time you hit 90% SOC with an AGM, even at .5C, you will have been in absorption for a while. As the batteries age and sulfate the point at which you hit constant voltage will happen even sooner.

[missourisailor]

Originally Posted by exMaggieDrum

Bruce, thanks for the reply regarding charging. Prices? I'll call your Seattle distributor.

The two 12V batteries (E31 and G31) have identical Ah ratings (e.g. 116Ah @ 20hrs) but the 4V battery has a whopping 346Ah!!! Could you confirm that please. Since the nominal voltage is 4V (versus 3.2 for the LFP smaller batteries), does it take only 3 batteries in series to make a nominal 12V (seems it should)? For 1038Ah!! in three batteries the size of a G31.

NEVERMIND! Mainesail beat me to this.

Yeah.. I think you got your math wrong.
For series batts you add the voltages and for parallel batts you add the capacity.

So for the 4v batt's you will need three of them to make 12v. But the capacity will be 346Ah.

If you put three of the 12v batteries in parallel, you will still have 12v but the capacity will be 348Ah.

Only two more Ah's for the 4v's.

Not worth the trouble. Also, after talking with Bruce Schwab yesterday, the 4v batt's are only a pipe dream and are not in production.

[CDN Paradigm]

I have two of the Firefly CF batteries and a Xantrex Link Pro Monitor. The batteries charge quickly (one hour) when I use a 30 amp Sterling Procharge unit but have noticed the monitor registering one battery falling in capacity after a day or so once the float state is achieved. Voltage in both batteries are within .01 of a volt but the total capacity falls. I've no idea if it is a battery issue or a monitoring issue.

[exMaggieDrum]

Originally Posted by Maine Sail

....

The magic of a Firefly not necessarily in its AGM acceptance rates but rather that you can cycle in bulk (bulk is nearly 100% efficient) many more times in between 100% recharges than you can with other AGM batteries.

If this cycling is from say 20% SOC to 80% SOC you are really using 60% of the banks capacity vs. traditional AGM's where you would cycle from 50% to 80% & use about 30% of the banks total capacity. Course this type of PSOC use would sulfate and damage a traditional AGM where a Firefly AGM could recover this lost capacity to go on and do another 20 -30 days between full recharges.

I would not concern yourself with max charge rates between any of the AGM's once you get above about .5C, as these are still lead acid AGM batteries and like any AGM they will take what they take until they become voltage limited.

The higher the current the sooner in the SOC curve you hit absorption voltage (constant voltage) and begin limited current acceptance. The lower the current the later in the SOC curve you hit acceptance limits. AGM's can benefit from higher charge currents but really there is a point at which throwing more at them means a less charge efficient cycle as you will just be in absorption the entire time.

This chart by Lifeline shows that by throwing more current at the battery the high current does not last very long. At 2C or 200% of Ah capacity bulk is over pretty much instantly.
....

Thanks Maine Sail, and Missouri Sailor. I had a fundamental "duh" moment on the Ah in series/parallel. You are entirely correct and I need to think more before hitting fingers to keys. Looks like no need to even think about the 4V batteries for the moment so no more on that. Still not sure what the differences are between a 12V E31 and G31 battery (if they sell the E31 at all since the 4V is on the website still as a product).

As far as concerning myself with max charge for the regular AGMs and CF AGMs I am assuming it does matter assuming you can still bulk charge the CF for the additional Ah replacement coming from 30% PSOC instead of 50% PSOC, i.e. stay in bulk for longer for the same Ah's replaced. If that is not a good assumption please let me know.

Thanks for reiterating the chart on AGM battery charging at different Amps per Ah capacity. I do need to "play battery" and compare with some numbers the differences between the LFP and the AGM batteries (including the CF type). It will really sink in for me that way.

So please excuse my babbling here as I attempt to talk my way through this. I get the differences in charging, life cycles, and all - just trying to put in it terms of real life on a boat, although with not totally realistic assumptions. What I am really trying to do is walk through this to get an idea of how to size the different types of batteries on a boat for the same daily amp budget. Then look at the total costs for each including the initial purchase price of the whatever Ah banks. Of course the total cost has to include the necessary robust charging sources, monitoring, and battery management equipment required for the different types.

E.g. assuming a daily 100Ah net usage, 100A (actual steady charge) charger for a 200Ah AGM battery, how many minutes would it take to efficiently replace the 100Ah of usable energy? A regular AGM could take .5C (or the whole 100A) for about 24min. If the battery were 100% efficient in recharge, then that would be 24/60x100A=40Ah, at which point the battery goes in to absorption charging so it will take less and less charge per minute. But you still need to take the regular AGM up to 100% again (or close to) otherwise you pay a very steep cycle life penalty. I.e. you can't just size up the bank so you only have to replace up to the 80% SOC, although you would get some additional cycle life by only going down to 67% SOC daily. You should be able to roughly figure out the daily engine run time required.

If the charger is an engine alternator, the motor is still burning (roughly) close to the same amount of fuel per minute as it was for the 100A full alt ouput but only putting in less and less of the amps. Fuel, noise, heat, engine wear and tear, etc. costs associated with that.

If I am understanding all this right, the LFP would be the winner in that it would not have any decrease in charge rate from 30% to 80% SOC so the run time would be dramatically shorter, and never has to get to 100%. Theoretically then the engine would only have to run for an hour using the same alternator. The CF would be second because it can start at 30% and take high bulk amps for longer than the regular tech AGM. It still only needs to get to 80% SOC most all the time (weekly or less often to 100%?). But it still will drop off from bulk to absorption charging at some point like any AGM, only it will be in bulk for more of the time, resulting in some additional time to get to 80% SOC. Some estimate of this could be made. The regular AGM needs to go from 50% (where it is closer to pushing back on the charge rate than the others) to 100% as much as possible - with a dramatic loss in cycle life if not done daily or thereabouts. So it would take X amount of engine run time over and above what the CF battery would need. You could go with a bigger AGM bank but there is no free lunch and you'll still need to run longer.

Once you have the battery bank size for each type of battery then it is straight-forward to calculate the initial cost of the installation (with potentially much more expensive alternators, etc), extrapolate to the time when you would need to replace each of the different types of banks, and come up with a total cost for a period of time, say for five years, assuming a steady X amps per day.

I'm just starting out thinking through all this so please bear with me. You guys have been looking at this for much longer.

[ranger58sb]

E31? 4V??


Not seeing any mention of either on Bruce's site...


??


-Chris

[Maine Sail]

Originally Posted by CDN Paradigm

I have two of the Firefly CF batteries and a Xantrex Link Pro Monitor. The batteries charge quickly (one hour) when I use a 30 amp Sterling Procharge unit but have noticed the monitor registering one battery falling in capacity after a day or so once the float state is achieved. Voltage in both batteries are within .01 of a volt but the total capacity falls. I've no idea if it is a battery issue or a monitoring issue.

Ah counters need very precise calibration, see the link below for much more detail. You also can not charge a lead acid battery in 1 hour. You can charge it part-way in an hour but it still takes many hours to get to 100% SOC and this is just the nature of lead acid batteries and why the Firefly is a great option because it allows you to not have to get back to 100% as often.

Programming A Battery Monitor


.

[Maine Sail]

Originally Posted by ranger42c

E31? 4V??


Not seeing any mention of either on Bruce's site...


??


-Chris

Guys,

Forget about the 4V battery and the 6V... We will be lucky to continue getting a small supply of the 12V G31 for a ways into the future. They are currently being hand built in small batches while they try and tool up to meet the demand.