Here is a
fixed link.
They do claim new technology which may have some substance. However they do not guarantee it for any longer than any other lead acid battery manufacturer. One of the limitations of most battery technologies is the calendar time: once the battery is manufactured, a clock starts and it will be junk in some period of time due to chemical degradation even if it is never discharged at all. For good AGMs this seems to be about 10-12 years.
So one question is, how many discharge cycles (and how deep) do you expect to have in the batteries warrantee period? 6 years of every weekend use and assuming 50% discharge each night used is only 624 cycles - which most batteries will tolerate. And that would be severe use for the batteries. Last weekend watching the battery monitor I was only getting down to 92% each night (two 6V batteries, 220 AH capacity). I wasn't running the heater (which is the largest energy consumer) but I was running the vent fan all night, lights, charging the computer, etc. When I run the heater in very cold temperatures (20 deg) I will go down to 80%. Over two nights with no charging down to 60%. But now with solar it is all recharged by noon the next day so never below 80%. My point is that unless you are living 365 off grid with unusual energy requirements you are unlikely to "wear out" batteries in a camper through too many cycles. Instead they will be killed by improper charging, sulfating them by self discharge during storage, or just calendar time.
So logically you should choose batteries based on criteria other than cycle life (assuming good quality in whatever technology). In the camper, I like AGMs mainly due to no outgassing corrosion, no maintenance, and low self discharge rates. Even self discharge is unimportant in a camper stored outside with solar charging.
That said, by all means you should buy those Fireflys and report back to us on how they work!
