Is death from carbon monoxide by charcoal burning as painless as they say?

This all depends. What happens is that the carbon monoxide combines with the hemoglobin in the blood. When this happens the blood can't carry enough oxygen to the brain that tells us when to do everything else including breathing. In a high concentration this will cause death in about 10 minutes. In a lesser amount it can also leave you with permanent memory loss and/or brain damage. I'm not sure why you need to know this, but please don't try this at all. The chance of you getting just poisoned and left with the damage is more likely then you being found dead. Who would you think would be the first to find you? Please think allot more about this. If you stop to think hopefully you'll think to stop. Good luck and God Bless