12V 116Ah Carbon Foam G31 AGM Battery with Exceptional Performance. Excellent for Solar, RV, Camping, Marine & Off-Grid. Lithium Ion Performance for Less Cost & Cold Weather Safe! Group 31 Deep Cycle

I bought 2 of the 12V G31 batteries and 3 of the large 4V batteries costing a total of $2900.14. The first year everything was fine. After that they just get worse and worse. By year 3 and 4, the only thing you'll be able to do with them is throw them out. With this kind of quality, they should be priced at less than half of an AGM battery considering that they only last 2 years. Instead, they are more than triple the price. Stay far far away from these batteries and don't believe all the hype. Go with standard AGM or Lithium. It's false advertising and the company should be sued.

I purchased 9 of these in July 2019 and installed them in August 2019. 2 identical house banks of 4 each and 1 separate start battery. I installed all new charging equipment to charge them exactly per the manual. House banks have been good. As of Decemeber 2019 the start battery has already failed. After fully charging to 14.4v and waiting for current to to drop to 0.6amps per the manual, and then completely disconnecting the battery terminals, the start battery sits at 10.7v. Never abused. Never even deeply discharged as it was just a start battery. It obviously won't start anything. Previously I had a plain lead acid Dyno Group 31 start battery that worked for 4 years until being replaced by the Firefly. Given the high cost I'm very disappointed.

Read the warranty. Degrades for every 10f above 80f.Not for my RV in Southwest USA. Marine boaters rave about them.BTW rumor is initial move to India had problems, per DIYSOLARFORUM

I bought a Firefly Oasis battery about four years ago. I am not easy on batteries. I accidentally put it through hell - two or three times accidentally dropping voltage down to around 5 volts. Each time it came back up like a champ. I couldn't believe it. Nor have I been reinvigorating it as I should yet it continues to soldier on. Any AGM or gel battery would have been quickly destroyed in my rig. I was sorry to hear about the other reviewers experiences. Apparently there were some quality control issues, but I can't say enough good about the one I have. There were some minor problems with the caps early on but those were easily fixed and don't seem to have affected the battery.

I installed 10 batteries less than 3 years ago. 8 batteries are for my house bank on my sailboat. With fewer than 100 cycles, the batteries have failed utterly and completely. These batteries are complete and utter rubbish. This company should not be in business.

Bought these batteries 2 years ago and have not been happy at all. They will not hold a charge, after charging them and letting them sit with the cables unhooked voltage will drop to 12.2 volts after 2.5 months. I have run my gen for hundreds of hours trying to keep charged. My old agm batteries lasted almost 9 years on my smart charger. Manufacture said they had some problems and that mine were bad from the start. I spent alot of money on these and wasted alot trying to keep charged. Buy something else.

These batteries are especially well suited for severe duty applications. Cycling to 50% DOD is unmatched in this battery chemistry. If this sounds like a commercial; just say that I am very impressed by FireFly.