Some thoughts:
A battery has less usable capacity when it's near freezing outside. Batteries also love being fully charged, especially if it's cold outside.
The alternator produces max output when you're on the move and on the throttle (i.e. >5000 rpm on a small bike). When you're idling or at very low speed, the alternator might be producing enough to power the lights and ignition, but it might not be producing enough extra current to recharge the battery at the same time.
If you aren't getting enough charge to top the battery sufficiently for a cold start, it might be a good idea to supplement the charging system on your Super 8 to get you through the winter months and prolong the battery. Some people like to go on a longer, faster ride to fully warm up the bike and get the battery fully charged once in a while. Others like to use a battery maintainer like the Deltran Battery Tender Jr. that they plug the bike into after they finish their ride. I do a combination of both.
Hope that helps steer you towards a solution.