Batteries, alternators, & solar - question on setup

[SeldomHere]

Hi folks,
I am about to pull the trigger on a F-RIB 430 and 30HP Yamaha 2-stroke, but given the wait for the F-RIB, through I would get my head around the electric side of things in the meantime.

I would prefer to opt for the electric start on the yammy, which then leads to having a starter battery. This is ok, as we do a lot of camping and it could double up as a campsite power source once we hit the beach. Which brings me to my head spinning conundrums.

- The yammy has an alternator so it could charge up the battery en route whist on the water.
- Whilst in camp, we would use solar to keep the battery(s) topped up (we get plenty of sun here in Hong Kong).
- We would only use the battery to run a camp fridge (about 5Wh max), and maybe a small projector.

There are lots of benefits for opting to go lithium, weight/lifespan/charging time/etc, but I have heard lithium can damage the alternator if not setup correctly (when fully charged it instantly cuts off the charge which can burn out the diodes in the alternator instantly).
An AGM battery would work well for the boat, but would be heavier and slower to charger on solar.

Has anyone here setup something similar?

Options I have as far as I can see:

a) Opt for Lithium and manage the BMS cut off for alternator charging with some electronic wizardry (any suggestions?)
b) Opt for AGM and manage the slower solar charge rates (bigger battery perhaps)
c) opt for hybrid and have a AGM for the boat, which stays on the boat and then have another solar/lithium system for camp (e.g. Bluetti 200max), but would double the weight of the setup.

Note: the boat will be packed up and brought home at the end of every trip (hence opting for a F-RIB) so everything I put onto the boat has to be carried on and off every trip. Yes, I know how much a 30hp 2-stroke weighs and am comfortable lifting it about with the help of an outboard trolley (and 3 weetabix for breakfast).

If it turns out to be too complicated, I may just opt for the manual pull start option and go fully solar.

Many thanks,

Tim

[warder54]

I would recommend the pull start option and get a nice 100ah + LiFePo4 battery, this newish generation is much safer from a fire hazard point of view. We have a 120ah LiFePo4 in our caravan, it's 50% lighter than AGM, with an MPPT solar charge controller (Very efficient) and a 200W solar panel, it charges rapidly (Esp in HK - I lived in Broadcast Drive, Kowloon for 2 years, 1976 - 1978) We have 2 TV's (24" and 32") use 2 laptops and mobiles and LED lighting. Last year here in Scotland we were "Off Grid" for 12 days and never went below 56% charge - they can be used right down to 5% without damage compared to 50% for AGM/LA, also has the benefit of still putting out 12.7v all the way down.