A Ki'ai power cell is a power source created by an extinct race known as the Ki'ai.
When a Ki'ai power cell is in use, it gives off strange readings and side effects that affect people's mentality. Individuals that come under its effects will start behaving oddly, such as babbling nonsense and become easily triggered into sudden violence.
Visually, a Ki'ai power cell resembles a group of translucent light blue crystals that give off a continuous white glow, regardless of whether or not it is in use.
SG-16 found some Ki'ai power cells and gave them to Dr. Lee for study. After he ran multiple simulations on the device, it was determined that the cells seemed compatible with Zero Point Modules, and should theoretically be safe. Because of this, General Landry sent one of the cells to the Atlantis expedition, to see if they could use it. Dr. McKay was skeptical, but the rest of the staff had already turned it on before he got there. Once the Ki'ai power cell was switched on, people around the city began to act oddly and violently. Woolsey ordered it to be turned off and as soon as Dr. McKay switched it off, people returned to their senses. After the event, Woolsey had the cell returned to Dr. Lee in Stargate Command. (SGA: "Stargate Atlantis / Stargate Universe Anthology 1")