I have been giving biochar a quick overnight charge when adding to the garden or potting soil. I use liquid kelp or pee. The pee char just goes in the garden, not potting soil.

I don't like wasting my pee, so I got a 5 gallon bucket with char. Once I started getting smell I added water and more char on top. This bucket was just placed in the shed until I was ready to use it.

Most of the char i have made gets mixed in with compost or chicken bedding for charging