B737 Captain reported a Lithium Ion battery powered wheelchair was incorrectly configured for transport. After conferring with ground personnel the Lithium Ion battery was securely attached to the wheelchair and required documents provided to the Captain; the aircraft departed safely.

Narrative

A Ramp Agent brought me a battery powered wheelchair form. The only box that was checked was the one next to Lithium ION Battery. I asked the Agent to send whoever loaded the wheelchair to come back up to the cockpit. When the Ground Agent arrived and I asked him about the subsequent selections in the Lithium Ion Battery box he said he only checks that top box; signs the bottom and that is it. When I attempted to point out that there were additional conditions that need to be met before transporting the battery; he said he would get a Supervisor. When the Supervisor arrived; I had to explain to him how the form works and that there was a checklist to follow. He went and talked to the customer and came back up and said the customer had the battery with them in the cabin; (crew members were not informed) so he circled B on the form; but still did not verify any of the subsequent conditions. When I asked him to verify that those 4 conditions were met; he went back to speak with the customer again; and discovered that Lithium battery was over 400WH which exceeds the cabin allowance. At that time; it was determined that we could only take the battery if was taken to the wheelchair and was securely attached to the wheelchair. The battery was finally transported in accordance with company procedures after a delay to rectify the improper loading.