Back in the NiCd era this hassle started mid-September and lasted until DST ended. Do I carry the lights and batteries today? What if I get sucked into a late meeting and don't get out on time? I've had these batteries on the bike for two weeks, will they make it home with the lights running tonight?

When the daylight time switch changed, it got more complicated: How much runtime is on these batteries already, how much is left?

Now in the dyno light era, things are so much easier: Look, I can see the headlight. It's working.