I installed Fireflys on my previous boat.
many of the benefits of Lithium, except the weight.
They will also charge using your conventional chargers.
I was pleased. I replaced a 600 amp hour, standard AGM house bank with 348 amp hour Fireflys and didn’t notice any reduction in usage, as you can discharge them deeper than conventional lead acid without damage.
today’s concern is that I can now find Lithium for similar prices as Firefly.