After a reluctant start yesterday (with final banging noise) I removed the battery and recharged it. It took somewhere between 6 and 12 hours of charge, meaning it was pretty low.

This happened on December 19th during the cold season, just about four months ago.

How often do you guys remove and recharge your batteries? Is this a normal thing to happen to my battery or should I be concerned about the alternator or battery?

I typically take short trips, i.e. 8-12 minutes or shorter, often with stops in between. 

Any opinions appreciated.

I have no answer for you but I was wondering the same thing. I left my bike sitting for four days while I went on vacation and when I got back it wouldn't start. Water level was fine. Switches were fine. After jumping it from my car it's just like new.

My current theory is that I don't rev high enough to recharge the battery. I recall a post here that claimed the battery doesn't charge below 5k rpm. Most of my riding is surface streets in stop-and-go traffic for my half-hour commute. As a newbie, I was car shifting most of the time which meant I wasn't getting enough revs to ever recharge the battery. Now that I've started shifting only when I'm up in the 8k range I haven't had anymore problems. We'll see though, this is just my theory.

-James

I was having a little bit of trouble starting my bike in the winter and just assumed that my battery was getting old, but then I checked the water level and it was really low, so after I topped it up I never had any problems. I usually do plenty of longer rides and even with heated grips always on I never have problems.

The short low speed rides don't fully recharge the battery and you may need to periodically recharge it.

Not riding the bike for over a week could cause a so so battery to discharge as well.

For the short rides/infrequent use You should consider a Battery tender and plug it in when it's going to sit for a long time or once every few days if you do short trips. No need to remove the battery (just make sure the vent tube is attached)

Batterys sometimes only last 3 years, so a new battery may help if it's an old batt, they don't last as long when used as described above either.

This is also why I wish bikes still had kick starters. Hopefully the 1977 Kawasaki Z1 that I'm going to look at tomorrow works out, it has a kicker!