It's not the quality of power, it's the constant short-cycle recharging
that kills the battery. I speak from experience.

Short periods of time on AC are okay, but leaving the laptop plugged in
and turned on for long periods is guaranteed to shorten battery life.

Cheers, Garrett

REad in one news report:
Investigators later determined an electrical short on board the 46-foot wooden boat Shell Lee
sparked the three-alarm fire. Damage was estimated at $10 million

This highlights  the importance of frequently checking your electrical panel and shore cord
connections.

Whether live-aboard or occasional user,  a loose connection will over-heat even when much less
than maximum current is drawn.
Having just last week done a service call on a brand new boat where a loose screw on the
Ship/shore selector switch caused the switch to melt and short out; I can attest to the facct age has
nothing to do with such  fire starters.

For your own peacce of mind, check all your power connections once a month  and look for any
sign of over heating.  Better yet, use an infra-red  thermometer to scan the energized  bus bars and
connections to detect incipient  hot spots before they develop into a fire.

Regards

Arild
Cheers