Drill bit with electrical power generation devices

1. A drill bit comprising:

a body including one of a magnet and a coil; and

a roller cone having cutting elements, the roller cone supported by a leg of the body and rotatable relative to the body, the roller cone coupled to the other of the magnet and the coil,

wherein rotation of the roller cone drill bit during drilling causes the body and the roller cone to rotate relative each other, thereby generating an electrical charge in the coil.

2. The drill bit of claim 1 , wherein the roller cone includes the magnet and the coil is at a surface of the body of the roller cone drill bit.

3. The drill bit of claim 1 , wherein the body includes a first member that carries one of the coil and the magnet and a second member that includes the other of the coil and the magnet, wherein the second member is coupled to the roller cone and rotation of the roller cone relative the body causes the second member to rotate in the bit body.

4. The drill bit of claim 3 further comprising a gear device that defines the rotation of the second member relative to the roller cone.

5. A roller cone drill bit comprising:

an electrical energy generation device placed in a body of the roller cone drill bit, wherein the electrical energy generation device includes a coil and a magnet, wherein one of the coil and the magnet is configured to move relative to the other of the coil and the magnet when a roller cone of the drill bit supported by a leg of the body and having a plurality of cutting elements is rotated relative the body to drill a wellbore.

6. The drill bit of claim 5 , wherein the coil is suspended in a space in the bit body and the magnet is stationary inside the bit body proximate the coil.

7. The drill bit of claim 5 , wherein the electrical energy generation device is a module placed in a cavity in the bit body.

8. A drill bit comprising:

a rotatable member placed along a surface of a bit body, wherein the rotatable member includes a magnet that is configured to rotate when the rotatable member comes in contact with a wall of a wellbore when the drill bit is rotated in a wellbore; and

a coil in the bit body proximate the magnet, wherein rotation of the magnet induces an electrical charge in the coil.

9. The drill bit of claim 8 , wherein the rotatable member is further configured to act as a stabilizer for the drill bit.

10. The drill bit of claim 8 , wherein the rotatable member includes an uneven surface configured to contact the wall of the wellbore.

11. The drill bit of claim 8 , wherein the induced electrical charge is used as one of; to charge a battery in the drill bit; to charge an energy storage device; to provide electrical energy to a component in a bottomhole assembly; and to provide electrical energy to one or more sensors in the drill bit.

12. A method of making a roller cone drill bit, comprising:

providing a body of the roller cone drill bit having one of a magnet and a coil; and

providing a roller cone configured to be supported by a leg of the body and to rotate relative to the body;

coupling the other of the magnet and the coil to the roller cone, wherein rotation of the drill bit during drilling causes the body and the roller cone to rotate relative to each other, thereby generating an electrical charge in the coil.

13. The method of claim 12 , wherein the roller cone includes the magnet and the body includes the coil.

14. The method of claim 12 , wherein the bit body includes the coil and the roller cone is coupled to the magnet, and rotation of the roller cone relative to the bit body causes the magnet to rotate in the bit body.

15. The method of claim 14 further comprising providing a gear device between the first and the second members configured to define the rotation of the second member relative to the roller cone.

16. A method of making a roller cone drill bit comprising:

placing an electrical energy generation device in a bit body of the roller cone drill bit, wherein the electrical energy generation device includes a coil and a magnet, wherein one of the coil and the magnet is configured to move relative to the other of the coil and the magnet when a roller cone of the drill bit having a plurality of cutting elements and supported by a leg of the bit body is used for drilling a wellbore.

17. The method of claim 16 , wherein the coil is suspended in a space in the bit body and the magnet is stationary inside the bit body proximate the coil.

18. The method of claim 16 , wherein the electrical energy generation device is a module placed in a cavity in the bit body.

19. A method of drilling a well, comprising:

conveying a drill string in the wellbore, the drill string including a roller cone drill bit at an end thereof, wherein the roller cone drill bit includes a body including one of a magnet and a coil and a roller cone having a plurality of cutting elements and supported by a leg of the body and rotatable relative to the body, the roller cone including the other of the magnet and the coil, wherein rotation of the roller cone drill bit during drilling causes the body and the roller cone to rotate relative each other, thereby generating an electrical charge in the coil;

drilling the wellbore by rotating the drill bit to generate the electrical charge in the drill bit; and

utilizing the generated charge downhole to perform a selected function.

20. The method of claim 19 , wherein the roller cone is further configured to be one of: a stabilizer for the drill bit and a cutting member.

21. An apparatus for use downhole, comprising:

a body of a roller cone drill bit including one of a magnet and a coil; and

a roller cone of the roller cone drill bit that is supported by a leg of the body and moves relative to the body, the roller cone including the other of the magnet and the coil when the apparatus is in use downhole, wherein

the relative motion between the body and the roller cone generates an electrical charge in the coil.