I have an EOS 7D that is well used. Recently purchased a 150-600mm lens (not a Canon). White out practicing with the lens, the camera started occasionally making an odd, mid-tone whining sound that seemed to be coming from from the battery compartmen...
The lens works really well but we have not eliminated it as the source of the noise since it did it on two different camera bodies. Have ordered a new battery but have not yet received it