On Thu, 4 Jan 2018 22:52:39 -0500, "Mr. Luddite"
wrote:

Don't know if it's still so but I remember in the old days you could
remove the battery from a car once it was running and it continued to
run just fine.

They always warned you not to but I did it on my 69 Corvette and
nothing bad happened. (dead battery, no cables and a borrowed battery
to get it going)
OTOH a new outboard (Yamaha or Mercury) will stop right away if you
disconnect or even have an open cell in a battery. (over voltage)
BTDT ... twice.