I was thinking about getting a second laptop battery and put it in my bag so that if I am out and do not have a plug, I will have some extra battery time. Is there a problem with carrying a loose battery around in the laptop bag?
Keep it in an anti-static bag and you will be fine. Actually all you need to do is keep the contacts from being shorted out. Even a sturdy plastic bag should work.
I usually carry mine in a separate compartment in my laptop bag away from metallic objects like keys & paper clips.
Some of the better bags used to come with a small Accessories pouch, (nominally for cables), which can be better used for a battery pouch - of course these days this sort of useful freebie is less common
Quote