A person who is a real piece of work. Someone either really complex or really screwed up or someone almost unbearably hard to handle.
The genesis of the term can be traced from a person being a real piece of "work" or a real "load" and multiple jobs and tasks are often done in "batches." Thus.. a person who is extremely screwed up can be called a "batchload"
That dude Zen, I swear is a friggin BATCHLOAD