This is a tread drift definitely but I wonder if any of the people fitting
Lithium batteries know about flooded NiCa as an alternative. Would be my first choice if I had a larger boat but I don't have room (or need) for a 900ah bank which was the smallest I could find at the time. NiCad was, and I think still is, a standard for large scale banks in the
power industry. I am talking about the batteries that keep the hospital equipment running while the generators get up to speed in a
power outage. They are practically indestructible, have a 20yr life can be cycled to 100% (recommendation is to store them discharged when not in use!), have no objection to C 1 charge/discharge rates (just in case you do have a 900a
alternator handy or 3 phase AC power!!) and are very well established technology. Initial cost is about twice FLA's but because of the larger DDC and longer life, over time they are cheaper.
They do of course have a down side, what doesn't. In this case it is an alkaline electrolyte which is rather dangerous if you spill it on skin. Same effect as strong bleach, skin goes soapy and dissolves but painlessly. There have been cases of severe damage because of unnoticed spills when a battery case case been damaged. This is however only when cells are used for.mining/caving as power for individual lights and case got damaged in a fall.
The other downside is that they are about 25% bigger than FLA's although I think lighter.
If you are looking for a power pack that can massive
current, take as much charge as you can throw at it and store a usable 900ah+ capacity they may be worth a look at what Wikapiadia says. (down the page, first part is the little sealed one like you have in a flashlight). Ignore the bits on cell memory, it only applies to sealed cells.