State of charge indicator and methods related thereto

1. A device for determining the mass of a fluid contained within a fluid enclosure, comprising:

a charge indicator that responds to a deformation of a solid component in contact with the fluid contained within the fluid enclosure, wherein the solid component is contained within the fluid enclosure and wherein the solid component is a composite hydrogen storage material that includes active material particles mixed with a binder;

wherein the deformation is a function of the mass of fluid contained within the fluid enclosure and wherein the deformation is used to determine the mass of fluid contained within the fluid enclosure.

2. The device of claim 1 , wherein environmental temperature changes introduce less than about a 1% error in determining the mass of fluid contained within the fluid enclosure.

3. The device of claim 1 , wherein environmental humidity changes introduce less than about a 1% error in determining the mass of fluid contained within the fluid enclosure.

4. The device of claim 1 , wherein environmental barometric pressure changes introduce less than about a 1% error in determining the mass of fluid contained within the fluid enclosure.

5. The device of claim 1 , wherein the deformation comprises a change in physical dimensions of the solid component.

6. The device of claim 1 , wherein the deformation comprises about a 1% deformation.

7. The device of claim 1 , wherein the deformation comprises about a 1% to about a 3% deformation.

8. The device of claim 1 , wherein the deformation comprises about a 3% to about a 10% deformation.

9. The device of claim 1 , wherein the fluid comprises a gas, a liquefied gas, a liquid or a combination thereof.

10. The device of claim 1 , wherein the fluid comprises a gas.

11. The device of claim 1 , wherein the fluid comprises hydrogen.

12. The device of claim 1 , wherein settling in the composite hydrogen storage material introduces less than about a 1% error in determining the mass of fluid contained within the fluid enclosure.

13. The device of claim 1 , wherein aging of the composite hydrogen storage material introduces less than about a 1% error in determining the mass of fluid contained within the fluid enclosure.

14. The device of claim 1 , wherein the solid component comprises a metal hydride.

15. The device of claim 1 , wherein the solid component comprises type AB, AB 2 , A 2 B, AB 5 , BCC metal hydrides or combinations thereof.

16. The device of claim 1 , wherein the solid component comprises LaNi 5 , FeTi, or MmNi 5 , wherein Mm refers to a mixture of lanthanides.

17. The device of claim 1 , wherein the solid component comprises clathrates, silicas, aluminas, zeolites, graphite, activated carbons, nano-structured carbons, micro-eramics, nano-ceramics, boron nitride nanotubes, palladium-containing materials or combinations thereof.

18. The device of claim 1 , wherein the solid component comprises the fluid enclosure, the fluid enclosure is a flexible fluid enclosure, and the flexible fluid enclosure is conformably coupled to the composite hydrogen storage material.

19. The device of claim 18 , wherein the charge indicator comprises a color change in the flexible fluid enclosure.

20. The device of claim 1 , wherein the charge indicator comprises a mechanical transducer.

21. The device of claim 1 , wherein the charge indicator comprises open cell foam.

22. The device of claim 1 , wherein the charge indicator comprises a fluid.

23. The device of claim 1 , wherein the charge indicator comprises a lever indicator.

24. The device of claim 1 , wherein the charge indicator comprises a visible window to view the deformation of a component.

25. The device of claim 24 , wherein the window is at about a 90 degree angle to the component.

26. The device of claim 24 , wherein the window is at an angle less than about a 90 degree angle to the component.

27. The device of claim 24 , wherein the window is at about a 90 degree angle to the fluid enclosure and wherein the fluid enclosure is flexible.

28. The device of claim 24 , wherein the window is at an angle of about 50 degrees to about 90 degrees to the component.

29. The device of claim 1 , further comprising a second fluid enclosure.

30. The device of claim 29 , wherein the second fluid enclosure contacts a fluid and wherein the fluid comprises substantially the same fluid as in contact with the first fluid enclosure.

31. The device of claim 30 , wherein the charge indicator associated with the first fluid enclosure maintains a charge balance with the second fluid enclosure, such that the charge correlates and the second fluid enclosure is not monitored.

32. The device of claim 1 , wherein the charge indicator comprises a mechanical indicator.

33. The device of claim 32 , wherein the mechanical indicator comprises a. mechanical linkage.

34. The device of claim 1 , wherein the charge indicator comprises a solid that changes an observable property when displaced.

35. The device of claim 1 , wherein the charge indicator comprises a liquid.

36. The device of claim 1 , wherein the charge indicator comprises an optical interference pattern.

37. The device of claim 36 , wherein the optical interference pattern comprises a grid.

38. The device of claim 36 , wherein the optical interference pattern comprises a faceted pattern,

39. The device of claim 36 , wherein the optical interference pattern comprises pixels.

40. The device of claim 36 , wherein the optical interference pattern provides one or more visible words upon straining of the component.

41. The device of claim 1 , wherein the charge indicator comprises a transducer.

42. The device of claim 1 , wherein the charge indicator comprises a charge-variable resistor.

43. The device of claim 1 , wherein the charge indicator comprises a strain gauge.

44. The device of claim 1 , wherein the charge indicator comprises an extensometer.

45. The device of claim 1 , wherein the charge indicator comprises a fiber optic strain gauge.

46. The device of claim 1 , wherein the charge indicator comprises a resistance strain gauge.

47. The device of claim 1 , wherein the charge indicator comprises an array of conductors on the surface of the component and in contact with one or more fixed brushes.

48. The fuel cell system of claim 1 , wherein the fluid enclosure is conformably coupled to the solid component.