Yes - you can add charcoal to your offset smoker BBQ while smoking. Unlike some popular briquettes that need to be ashed over before cooking and can also give off chemical smells during that initial burn, natural lump charcoal can be used immediately.
The first thing you need to do is make sure that your charcoal is of good quality. This means choosing a brand that burns evenly and doesn't produce too much ash. Once you've got your charcoal, it's time to get started.
We highly recommend gidgee charcoal, Flaming Coals Lump charcoal and Flaming Coals HotRods. These are made of natural charcoal timber burned into charcoal and the hotrods are processed charcoal that doesn't have any added chemicals other than timber sawdust so they have a neutral flavour.
When adding the charcoal to the smoker while smoking, we recommend not waiting until the charcoal burns right down but plan ahead. If the coal base is half to three-quarters of what you had, add the fresh charcoal alongside the burning coal so it slowly catches alight and maintains a steady burn. Adding fresh charcoal on top of burning charcoal can initially smother your fire then there will be a temperature spike when it all catches so try and avoid doing this.