Moderation is key. Consume just what is needed and come back to it later if you need more. I find if I know I'll need pain relief I'll just eat an edible before I leave and right after I'll have a quick session. Usually they're timed out so I'm usually okay without feeling overly "burnt"
I would say you'd still need to charge it, but my guess is occasionally. Might kill off the battery's life span though in the long run, but doesn't sound like you're that worried if you'll have more batteries.
Edit-beat to the punch