Number of cycles and how deep always drives a batteries decline. The Firefly has a design cycle life of 1000 cycles to 80% DOD and 3600 cycles to 50%. The carbon foam makes this possible. The carbon foam limits and minimizes the sulfate from hardening and clustering something that murders other batteries when PSOC cycled.
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CMS - " design cycle life " mentioned in your above.
Is that computer design only? Have several randomly chosen Firefly batteries been hands-on tested, utilizing normalized marine conditions, to prove their ability that they can actually reach these stated levels of 1000 cycles for 80% DOD and 3600 cycles for 50% DOD?
It is not just computer design. They run then look at various tests, various temps, various discharge rates and then project design life using industry accepted calculations to arrive at DOD to cycle life under "ideal" conditions.
This is no different than how other manufacturers do it Firefly just calls it "design cycle life" and some other battery makers insinuate they have tested all batteries at all SOC depths for cycle life. This would take eons to do, tie up millions of dollars of test equipment etc. and it is not done. Almost all cycle life graphs are projected. While based on actual testing they are still using mathematical projections. Sadly ideal conditions do not exist in the real world. This is why I created my own PSOC test when the Firefly was shown to me. I'm a skeptic at heart...
While short in duration (data collection actually took over 6 months) this PSOC testing was enough to see marked differences in PSOC performance and cycle life degradation. Now if we could only get the industry to adopt a similar test we'd all have significantly better data with which to buy batteries.
The Firefly batteries have undergone numerous tests both independent and in their own lab. One test took a FF to 100% DOD (0% SOC) each cycle at a 1C discharge rate (116A for a 116Ah battery) at 25°C/77°F and it survived this 1250 times before falling to 80% of its original capacity.
In an independent J2185 Test, which is at 50°C/122°F, the Firefly ran for 724 cycles at 50% DOD. This is pretty insane at 122°F when you consider that a rise of just 10°F beyond 77°F can halve the cycle life of a lead acid battery.
The Firefly delivered a cumulative 35,108 Ah's and the Odyssey Group 31 PC2150 TPPL AGM, (another very good AGM) delivered just 7815 Ah's. This is actually pretty respectable at those temps. In that same test a Deka G-31 flooded battery delivered just 3264 cumulative Ah's.
Manufacturer claims on
cycle life almost never stack up in the marine market because no one tests for PSOC capability, how many of us use batteries, nor do they all use the same test criteria. Lab data is really only
sort of telling within a brand. For example if Trojan suggests that the T105 will do 1200 cycles to 50% DOD and the SCS-225 (group 31) will only do 600 cycles to 50% that is decent information
within the Trojan line up. If Deka says their G-31 flooded will do 350 cycles and their golf cart battery will do 1000 cycles that too is good data
within the Deka brand under ideal lab conditions...
Some outside the battery industry have been pushing BCI to initiate PSOC ratings to make it fairer to understand how a battery might fair in the real world of off-grid, RV or marine applications. Sadly the industry fights this tooth and nail.
So yes, this is why I said "
design cycle life". From what I have seen I still suspect that in a PSOC application the cycle life of the Firefly should be considerably better than other AGM batteries. Also I don't think most realize how many cycles 1000 really is, it is a LOT. I have been working my LiFePO4 battery really hard for nearly 5 years and still have not broken 800 cycles to 80% DOD and I am regularly cycling it to 80% DOD in the off season...
Kind of like feeding a new common rail diesel through an 80 micron filter with dirty fuel... Might work for a short time but eventually it's going to cost you $$$. 
