[Hunter450]

Not sure what kind of cranking amps a 150 hp outboard draws but you might want to confirm that the cranking amp requirements match the capacity of your proposed lithium batteries. Does that "old bass boat" start up in under 3 seconds or it a 15 second starter?

You would hate to "suck the guts" out of your lithium golf cart batteries by using them as starter batteries ... I am not sure if they are really designed for that.

Yeah, my old motor takes about 5 secs to crank after the long winter. A day or two before the fishing trips, I'll start and run the outboard at the house. Usually, just a bump of the key and she fires off.

The bass fishing market is pushing the lithium drop replacements and some of those guys (pro's-semi pro's) have been running lithium's in their boats for over five years and just praise how they perform. The 125AH battery seems to be the choice for cranking 250hp motors so I'm pretty confident the 2-100AH batteries wired in parallel will spin my 150.

Another neat aspect is each battery has it's own BMS and is Bluetooth capable. Just download the app to your phone and you can monitor in real time the actual condition of each battery.