Battery acid status indicator and method for production thereof

1. An acid status indicator for a lead-acid rechargeable battery, having:

(a) a sight glass ( 14 ) having a bead provided about the circumference of the sight glass and a head ( 22 ), wherein the bead is disposed in a middle section of the head, spaced apart from an upper end of the head; and

(b) a holder ( 12 ) for holding the sight glass ( 14 ) and for attaching the acid status indicator ( 16 ) to a housing ( 10 ) of the battery ( 11 ), the holder having an engaging projection which is received by the bead, wherein the bead is surrounded by the holder ( 12 ) in an interlocking manner, thereby preventing any movement in the axial direction of the sight glass ( 14 ) relative to the holder ( 12 ), the holder and the sight glass being connected to one another by a gas-tight shrink fit,

wherein the sight glass ( 14 ) comprises a first plastic and the holder ( 12 ) comprises a second plastic, with the first plastic shrinking less than the second plastic when it cools down.

2. The acid status indicator as claimed in claim 1 , wherein the sight glass ( 14 ) comprises styrene/acrylonitrile.

3. The acid status indicator as claimed in claim 1 , wherein the holder ( 12 ) comprises polypropylene.

4. The acid status indicator as claimed in claim 1 , wherein the sight glass ( 14 ) has a stepped end in order to indicate different acid levels.

5. The acid status indicator as claimed in claim 1 , wherein the sight glass ( 14 ) has a projection at the lower end, which projection is used to hold a ball cage to indicate the acid density.

6. A lead-acid rechargeable battery, having an acid status indicator ( 16 ) as claimed in claim 1 .

7. The acid status indicator of claim 1 , wherein the sight glass ( 14 ) and the holder ( 12 ) are two-component injection molding parts, with the holder ( 12 ) being an insert mold of the sight glass.

8. An acid status indicator for a lead-acid rechargeable battery, having:

(a) a sight glass ( 14 ) and

(b) a holder ( 12 ) for holding the sight glass ( 14 ) and for attaching the acid status indicator ( 16 ) to a housing ( 10 ) of the battery ( 11 ), the holder being shrunk onto the sight glass and resting completely on the sight glass such that the holder and the sight glass are connected to one another by a gas-tight shrink fit.

9. An acid status indicator for a lead-acid rechargeable battery, having:

(a) a sight glass ( 14 ) having a bead provided about the circumference of the sight glass and

(b) a holder ( 12 ) for holding the sight glass ( 14 ) and for attaching the acid status indicator ( 16 ) to a housing ( 10 ) of the battery ( 11 ), the holder surrounding the bead in an interlocking manner, the holder and the sight glass being connected to one another by a gas-tight shrink fit.

10. The acid status indicator of claim 8 , wherein the sight glass further comprises a head and a bead, wherein the bead is disposed in a middle section of the head, spaced apart from an upper end of the head.

11. The acid status indicator of claim 9 , wherein the sight glass further comprises a head, wherein the bead is disposed in a middle section of the head, spaced apart from an upper end of the head.

12. The acid status indicator of claim 10 , wherein the bead is surrounded by the holder ( 12 ) in an interlocking manner, thereby preventing any movement in the axial direction of the sight glass ( 14 ) relative to the holder ( 12 ).

13. The acid status indicator of claim 11 , wherein the bead is surrounded by the holder ( 12 ) in an interlocking manner, thereby preventing any movement in the axial direction of the sight glass ( 14 ) relative to the holder ( 12 ).