Posted on October 15, 2010.
Motion detector wireless Wii turns off after a few minutes and battery light blinks constantlya I bought a Wii Sensor Bar Ultra and immediately noticed when using the battery light starts flashing on and off after about 3 minutes. regardless of the activity.
Looks like you need to replace the batteries. Sometimes that is what must be done immediately, because who knows how old these "new" batteries are really;)