I updated to current on 16 1532Z July from April current, and it mostly
seemed ok other than racoon not starting and some coda oddness.

I shut my Thinkpad T60 down and when I got home and plugged it in the
orange charge light was flashing (indicating bad battery).  The system
booted up and then:

ul 16 19:43:03 poblano /netbsd: boot device: wd0
Jul 16 19:43:03 poblano /netbsd: root on wd0a dumps on wd0b
Jul 16 19:43:03 poblano /netbsd: root file system type: ffs
Jul 16 19:43:03 poblano /netbsd: acpibat1: critical capacity limit on 'acpibat1 charge'

and then it ran shutdown.  I booted again, not yet realizing blinking
yellow was bad, and thinking that there would be enough charge to be
above critical.  This time shutdown apparently had a time race and it
was telling me: 'no logins; shutdown at 18:55' but it was after 18:55.
I had to power cycle and fsck to recover.

So there are at least two bugs here:

  acpibat1 being critical while acpibat0 is at 99% is not cause to do
  anything other than perhaps log the occurence.  This is just what
  happens with two batteries.

  batteries being at critical charge while the AC adapator is present is
  not cause for shutdown.

I'm inclined to turn the shutdown in /etc/powerd/scripts/sensor_battery
into a warning until a cleaner solution is found - the current state is
too dangerous.  Objections?