Interesting, I've been studying this on and off for a couple years now, good to see this discussion!
The Lilied website gives me pause as zero technical information is available.
The info on the DIY forum and printed on the battery claims 800 amps maximum current, but neither claim comes with a temperature rating for that scenario, so it's impossible to tell if the amps are adequate for cranking the engine. My Suzuki 250 requires 800A marine cranking amps (32F) or 1000 cold cranking amps (0F). A group size 48 battery is quite small, so I have serious doubts about the claims here.
My main concern as a start battery is how it shuts itself down once charging is done - does it just disconnect the load? If so, it will destroy the alternator, which cannot withstand a sudden disconnect of current and associated instantaneous spike in back-voltage. Perhaps if you install an alternator protector, such as sold by Sterling? But remember those are intended for stand-alone alternators rather than outboard alternators so I'm not at all sure it's appropriate for an outboard.
As a house battery it seems like it may work fine. I like that it has posts on each corner. However, up against the Kilovault batteries from AltE store, without a lot more information, these give me way more questions than answers, and the Kilovault batteries appear to have better charge/discharge specs, although I think most of that is from the fact that the Lilead battery is smaller than the smallest Kilovault battery, which could mean the Lilead's smaller size is it's greatest potential advantage here.
Personally, I would not run a lithium start battery on an outboard boat - I don't think the BMS is ready to protect the outboard alternator adequately. As a house battery, with a battery to battery charger from an AGM start battery, is where the sweet spot is. The other issue with lithium as a house battery is that they really don't want to see a constant trickle charge, as from a solar panel or small charger as pictured (the Noko). They want a bulk charge, a short absorption charge, then nothing. I've been looking into it for my boat and given that I'd have to change all 3 of my solar charge controllers plus add some sort of control to shut them down when the battery was fully charged, it's just too much $$ and time to save the 25 or so pounds.
I think Victron and Kilovault are the best options here, with Victron offering a more or less complete solution for marine applications, but again, not geared toward outboard boats, so there are issues to resolve here. I think for outboard boats, the only way to go is with the battery to battery charger, and again, leave a "standard" lead acid battery (or AGM) as the start battery to prevent any problems with the outboard.
