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[hopkinslaw]

It is time to replace the house batteries on my 1990 Catalina 30. I can fit two group 31s as a bank under my dining bench. After some research on what battery to buy the clear choice is a pair of Firefly batteries.  https://www.bruceschwab.com/advanced-energy-storage-systems/firefly-energys-oasis-group-31/

I'm a bit puzzled at how clear the choice seems given that Firefly batteries remain a niche product.

It seems to me that for about 2-3 times the price I'd pay for a flooded or AGM battery the Firefly gives me:
1. maybe 8-10 times more life (3600 cycles to 50%DOD)
2. more usable battery capacity because these batteries can be regularly discharged 80% or more without damage. This is impossible with flooded batteries and likely destructive to most AGM batteries.
3. partial charging. These batteries claim not to suffer sulfation even if repeatedly partially charged. This means I can anchor for longer. I don't need to run my engine needlessly to push my batteries slowly up from 85% charge. When cruising I don't have to spend a night at a marina every week to get my batteries up to 100%.

If all this battery did was deliver on promise 1 it would make mathematical sense to buy these batteries over anything else I've considered. Item 2 is a massive bonus. Item 3 is great and it also locks in the other benefits. I'm more likely to actually get to use the extra cycles the battery promises because I won't ruin the battery through partial charging.

Three questions.
A. Why are the experts lukewarm about these batteries? Practical Sailor confirmed much of the marketing claims but stopped short of recommending the batteries saying further testing is required. Nigel Calder said much the same. I understand these batteries were developed 10 years ago. Why is there not better data on whether they truly deliver the promised number of cycles in the wild?

https://www.bruceschwab.com/wp-content/uploads/sites/86/old/firefly-testimonial-nigel.pdf
https://www.practical-sailor.com/blog/Can-Carbon-Foam-Batteries-Meet-Hype-11694-1.html

B. Why do Fireflies remain niche items? Obviously it's a big ask to shell out 2-3 times more money for a battery up front but overall cost of ownership appears to be much lower. Is the choice not quite as obvious as I have made it seem?

C. What else might cause these batteries to die? If I keep them above 50% DOD it could be decades before I cycle my batteries 3600 times.

Cheers.

-David Hopkins
1990 Catalina 30 5845
Vancouver

[mainesail]

A. Why are the experts lukewarm about these batteries? Practical Sailor confirmed much of the marketing claims but stopped short of recommending the batteries saying further testing is required. Nigel Calder said much the same. I understand these batteries were developed 10 years ago. Why is there not better data on whether they truly deliver the promised number of cycles in the wild?

They are lukewarm because the company is small, unproven and has failed to keep up with demand. There have been many companies like this in the past that did not survive.

B. Why do Fireflies remain niche items? Obviously it's a big ask to shell out 2-3 times more money for a battery up front but overall cost of ownership appears to be much lower. Is the choice not quite as obvious as I have made it seem?

IMHO it us because the current Indian owner of the company does not take this business seriously nor is he willing to properly fund the expansions needed to keep up with demand. He recently pulled manufacturing from the US and moved it to India. The US importer (Bruce) and Illinois lab have been left to do the QC & testing. The biggest issues, when they were built in the US, were the India manufactured components, such as bad valves. Firefly US stood behind a number of battery failures due to these bad valves but still QC in India has not been what it should have been.

Cost is another factor and to many boaters are incapable of the math. Another issue is that many owners don't buy these batteries then use them as they are designed to be used, and by that I mean cycling regularly to 80% DOD. If you are not using the full potential of the battery you are wasting money on Firefly's.. When cycled to 80% DOD and compared to batteries that can only cycle to 50% regularly, the cost becomes a non-issue. Again, too many folks are incapable of this math.

The other issue is supply. These batteries are very, very hard to get. Containers are usually 100% sold by the time they get to the US.

C. What else might cause these batteries to die? If I keep them above 50% DOD it could be decades before I cycle my batteries 3600 times.

Please don't waste your money on Firefly unless you plan to actually use them to 80% DOD. Batteries also die of simple calendar age, even if not used or cycled at all. Far too many people have misconstrued the Firefly to be "Permanent PSOC capable" and it is NOT. I like to see them get to 100% every 14 days or so, due to walk-down capacity loss, and then have "wake-up" cycling run at least bi-yearly. Wake-up cycling is pretty unique to Firefly and is taking the battery to 0% SOC to 5% SOC, under a 20 hour load, then recharging to 100%, at least two times, back to back. This re-opens the pathways and allows the battery to again perform at or near 100%. Incorrect charging will also murder a Firefly. 14.4V and 13.2V temp compensated for all charge sources is optimal. Kurtis, the inventor, actually prefers no float but has begrudgingly agreed to raise the float threshold to 13.4V "if you must" because far too many "dip-switch" chargers are simply incapable of charging the Firefly "properly".......

The Firefly technology is simply amazing but the company has had a few stumbles getting going. Supply is still a major issue.. I suspect the lions are just sitting there waiting for the patent to expire so they can pounce..

[hopkinslaw]

So the saying "build a better mousetrap and the world will beat a path to your door" is incomplete. You need to also build a good distribution network and quality control.

Thanks Maine. Interesting theories.

[mainesail]

So the saying "build a better mousetrap and the world will beat a path to your door" is incomplete. You need to also build a good distribution network and quality control.

Thanks Maine. Interesting theories.

Yes they have suffered a few growing pains but the technology actually works.. I have done more independent third-party PSOC testing of this battery than anyone else I know of and have been experimenting & using them since 2013.

The test battery from the 2015 Practical Sailor PSOC testing is still being abused, when not on-board my own boat as the "reserve battery". As of Nov still tested with 100% of original capacity. It is the only lead acid battery I have seen that can actually handle 80% DOD cycling and shake it off like nothing happened. You really should read the full Practical Sailor articles May 2015 and August 2015..

In the Practical Sailor PSOC testing all the AGM batteries were treated equally and there were massive variances in permanent capacity loss over just 30 cycles of deep-cycle PSOC use where the batteries were discharged to 11.7V at the 20 hour rate then recharged for exactly 1 hour at a .46C charge rate. A LifePO4 battery was used as a control, as they do not sulfate.

CALB LifeP04 - Lost 0% of Ah Capacity in 30 PSOC Cycles
**Firefly AGM - Lost 0% of Ah Capacity in 30 PSOC Cycles
Odyssey TPPL AGM - Lost 6.5% of Ah Capacity in 30 PSOC Cycles
**Northstar TPPL AGM - Lost 8.5% of Ah Capacity in 30 PSOC Cycles
Lifeline AGM - Lost 11.6% of Ah Capacity in 30 PSOC Cycles
Deka / East Penn AGM #1 - Lost 29.7% of Ah Capacity in 30 PSOC Cycles
*Deka East Penn AGM #2 - Lost 27.5% of Ah Capacity in 30 PSOC Cycles

*A second battery was tested because initial results were so poor.

**Marketed as sulfation resistant.

Capacity losses over 30 cycles were not recoverable, beyond what is shown, in any of the batteries that lost capacity. This means the damage & capacity loss from sulfation can be permanent in less than 30 cycles.

Unfortunately trying to predict cycle life, based on lab data, even Firefly's data, does not work in the marine environment until the manufacturers start giving us PSOC data. The cycle life data we get from the battery industry is about as good as the data Volkswagen gave the EPA on their "clean diesels," pure fairy tale...

I am in no way trying to steer anyone away from Firefly just to be realistic about the supply chain, math and potential for a QC issue, (though it is very small these days). As lead acid batteries go the Firefly may very well be the least expensive, based on what I have seen these batteries survive.

[KWKloeber]

It is time to replace the house batteries on my 1990 Catalina 30. I can fit two group 31s as a bank under my dining bench.

David

If you need more AH to reduce your DOD/extend cruising/on-hook range, I fit 3 Gp 31s under the quarter berth.  On the Mk-II, you probably can't fit the 3rd due to the water heater, but 2 should fit.  These aren't in-addition, I moved the house/start batts from the nav station (MK-I) to claim the storage room in the cabinet.  I could have 3 house, but currently use one as my reserve (which I could theoretically add in the engine compartment.)

Ken
C30 #3573