Float Valve for Lead Acid Battery
FIELD OF THE INVENTION
The invention relates to a cap assembly for a lead acid battery. More particularly the invention relates to a cap assembly wherein the electrolyte level in a cell of the lead acid battery can be estimated from the outside.
BACKGROUND TO THE INVENTION
A lead acid battery is particularly useful in portable or stationary backup power solution applications. Lead acid batteries can be of many types. A common type of lead acid battery is the flooded battery. In this battery the acid is not fixed in gel or absorptive glass mat. During charging some of the water in the electrolyte decomposes into hydrogen and oxygen gas. Pressure builds up in the battery housing and the battery could, under certain circumstances, explode in case the gases are not vented. All flooded lead acid batteries therefore have a vent hole in the cover for permitting escape of gases.
Conventional lead acid storage batteries comprise a container, a cover, a plurality of battery cells with each battery cell comprising positive and negative plates and a cap assembly for each battery cell. Often electrolyte level indicators are a part of the cap assembly of the battery cell. The cap can be removed to permit filling or removal of electrolyte from the battery cell. The cap normally is vented in order to permit escape of gases that build up during the use of the lead acid battery.
For proper operation of the flooded lead acid battery it is necessary to maintain the electrolyte concentration within predetermined limits. It therefore becomes necessary to periodically add water to the electrolyte. Flooded lead acid batteries therefore have one or more holes in the cover through which water can be added. These holes are either plugged or otherwise closed when the filling operation is completed.
On account of the vent hole, electrolyte tends to spill out of the battery during transportation, handling and operation. This loss of acid can cause external damage and needs to be avoided.
The life of a lead acid battery can be reduced by failure to maintain proper electrolyte level in each battery cell of the lead acid battery. It is therefore important that the electrolyte level in each battery cell should be readily observable.
There is therefore a need for a cap assembly for each cell of a lead acid battery wherein the electrolyte level is readily observable from the outside. It is also necessary to transport, handle and operate the lead acid battery with the cap assembly in place. Further there is a need for a cap assembly wherein the evaporation of electrolyte is reduced.
SUMMARY OF THE INVENTION
The present invention in one aspect relates to a cap assembly for a lead acid battery. More particularly the present invention relates to a cap assembly comprising a float assembly. In another aspect the invention relates to a lead acid battery wherein the electrolyte level can be estimated from the outside.
This summary is provided to introduce a selection of embodiments in a simplified form that are further described below in the detailed description. This summary is not intended to limit the scope of the claimed subject matter.
The present invention in one embodiment relates to a cap assembly for a cell of a lead acid battery, such cell comprising electrolyte, the cap assembly comprising a transparent cap comprising vent holes; a float assembly comprising an upper portion, middle portion and a bottom portion such that the upper portion can be seen within the transparent cap and the bottom portion is connected at one end to the middle portion; a ring assembly comprising a cylindrical ring and a casing such that the cylindrical ring comprises a top portion and a bottom portion; the casing comprises an inside wall and a protrusion on the inside wall such that the top portion of the cylindrical ring can rest on the protrusion when the level of the electrolyte is below a first predetermined level.
The float assembly is aligned such that the upper portion is above the cylindrical ring and within the transparent cap; the middle portion passes substantially through the cylindrical ring and can move freely within the cylindrical ring; the bottom portion is
in contact with the electrolyte such that when the level of the electrolyte is above a second predetermined level, the bottom portion is in contact with the bottom portion of the cylindrical ring.
It would be clear to a person skilled in the art that the movement of the float assembly is dampened when the level of the electrolyte is above the second predetermined level. The cap assembly of the present invention thus can be of a lesser length than the cap assemblies of the prior art. This leads not only to the saving of material but also to easier handling, less damage and ease of transportation of the lead acid batteries of this invention.
The second embodiment of the invention further comprises the transparent cap of the previous embodiment wherein the transparent cap has markings on it. The presence of the markings makes it easier to estimate the level of electrolyte and to easier notice the movement of the upper portion of the float. This ensures better maintenance of the electrolyte level in the battery cell.
The third embodiment of the invention comprises the previous embodiments wherein the top portion of the cylindrical ring has ribs that extend towards the bottom portion of the float assembly. The ribs ensure that the contact between the cylindrical ring and protrusion on the inside wall of the casing is minimal and the chances of the cylindrical ring and the float sticking to each other are reduced.
The fourth embodiment of the invention comprises any of the previous embodiments wherein the cap assembly further comprises an annular disc such that the annular disc is fixed to the casing; the cylindrical ring is below the annular disc; the middle portion of the float assembly passes through the annular disc; and the top portion of the float assembly is above the annular disc.
The presence of the annular disc ensures that electrolyte does not spill out of the cell. This makes the handling of the lead acid battery easier.
The fifth embodiment of the invention comprises the cap assembly of any of the previous embodiments wherein the top portion of the cylindrical ring is shaped like a funnel. This ensures that any electrolyte that either condenses or collects at the
transparent cap or the annular disc can flow back through the funnel. This reduces chances of the electrolyte accumulating between the upper portion of the float assembly and the transparent cap and the upper portion of the float assembly sticking to the transparent cap.
The sixth embodiment of the invention comprises the cap assembly wherein the transparent cap comprises a top portion and a bottom portion such that the bottom portion comprises a first knife edge substantially centered on the bottom portion. This ensures that the contact between the upper portion of the float assembly is minimized and the chances of the upper portion sticking to the transparent cap reduced. The term "knife edge" as used in this invention includes any sharp protrusion.
The seventh embodiment of the invention is an alternate to the previous embodiment and comprises the cap assembly wherein the upper portion of the float assembly comprises a second knife edge wherein the second knife edge is substantially centered on the upper portion.
The eighth embodiment of the invention comprises either of the previous embodiments wherein the bottom portion of the float assembly is either a disc or cylindrical, spherical or conical. It would be clear to a person skilled in the art that the bottom portion of the float can be one of many shapes.
In another embodiment invention comprises a lead acid battery further comprising the cap assembly of any of the previous embodiments.
It is reiterated that the above embodiments only by way of example and that the invention can be embodied in many other ways evident to a person skilled in the art. The above embodiments are intended to only exemplify the various manners in which the invention can be embodied. The embodiments are not intended to limit the scope of the invention. The invention, as would be evident to a person skilled in the art, can be exemplified in many other ways.
DRAWINGS
Fig. 1 describes a cap assembly 311 of a battery cell 31 of a lead acid battery 3 of the present invention.
Fig. 2 A describes a cap assembly 311 of the present invention.
Fig. 2B describes a ring assembly 341 of the present invention.
Fig. 2C describes a casing 345 of the present invention.
Fig. 3A describes a battery cell 31 wherein the electrolyte level is maintained at first predetermined level A.
Fig. 3B describes a battery cell 31 wherein the electrolyte level is maintained at second predetermined level B.
Fig. 4 describes a transparent cap 301 of an embodiment of the present invention.
Fig. 5A and Fig. 5B describes cylindrical ring 343 and its assembly wherein the top portion 343A of the cylindrical ring 343 has ribs 351.
Fig. 6 describes cap assembly 311 in accordance with an embodiment of the present invention.
Fig. 7 describes the cap assembly 311 wherein the top portion 343A of the cylindrical ring 343 is shaped like a funnel.
Fig. 8 describes a transparent cap 301 of cap assembly 311 of a battery cell 31 wherein the transparent cap 301 comprises a first knife edge 361.
Fig. 9 describes a float assembly 305 of a battery cell 31 wherein the upper portion 313 of the float 305 comprises a second knife edge 372.
Fig. 10A, Fig. 10B and Fig. 10C describe float assemblies 305 of cap assembly 311 wherein the bottom portion 317 of the float 305 is either a disc, spherical and conical respectively.
DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION
The present invention is described with reference to the following embodiments. It will be evident to a person skilled in the art that the following embodiments are by way of example only and that the invention can be exemplified in many other ways. The embodiments are not intended to limit the scope of the invention and the invention can be exemplified in many other ways evident to a person skilled in the art.
The invention is general in nature and the battery of this invention can comprise any number of cells.
Embodiment 1:
Fig. 1 describes a cap assembly 311 for a cell 31of a lead acid battery 3, such cell 31
comprising electrolyte 321.
Fig. 2 describes a cap assembly 311 for a cell 31 comprising:
a. a transparent cap 301 comprising vent holes 303. The cap can be
constructed of material such as transparent acid resistant plastics or
other materials known to the art;
b. a float assembly 305 comprising an upper portion 313, middle
portion 315 and a bottom portion 317 such that the upper portion
313 can be seen within the transparent cap 301 and the bottom
portion 317 is connected at one end to the middle portion 315. The
float can be constructed of material such as acid resistant plastics,
ceramic or other materials known to the art. The upper portion 313
can be of a color different from the color of the middle portion 315
or the bottom portion 317 of the float 311 so that it is visible within
the transparent cap 301;
c. a ring assembly 341 shown in detail in Fig. 2C comprising a
cylindrical ring 343 and a casing 345 such that:
1. the cylindrical ring 343 comprises a top portion 343A and a bottom portion 343B;
2. the casing 345 shown in detail in Fig. 2C comprises an inside wall 347 and a protrusion 348A on the inside wall 347 such that the top portion 343A of the cylindrical ring 343 can rest on the protrusion 348A when the level of the electrolyte 321 is below a first predetermined level A. The cylindrical ring 343 and the casing 345 can be constructed of materials such as acid resistant plastic or other materials known to the art. d. The float assembly 305 is aligned such that:
1. the upper portion 313 is above the cylindrical ring 343 and within the transparent cap 301;
2. the middle portion 315 passes substantially through the cylindrical ring 343 and can move freely within the cylindrical ring 343;
3. the bottom portion 317 is in contact with the electrolyte 321 such that when the level of the electrolyte 321 is above a second predetermined level B, the bottom portion 317 is in contact with the bottom portion 343B of the cylindrical ring 343.
Fig. 3 A and Fig. 3B describe the cap assembly 311 where the level of the electrolyte is at
first predetermined electrolyte level A and second predetermined electrolyte level B
respectively.
Embodiment 2:
The second embodiment of the invention as described in Fig. 4 further comprises the
transparent cap 301 of the previous embodiment wherein the transparent cap 301 has
markings 322 on it. The markings 322 can be painted using acid resistant paint or using
other techniques known to the prior art.
Embodiment 3:
The third embodiment of the invention as described in Fig. 5 & Fig. 5A comprises the
previous embodiments wherein the top portion 343A of the cylindrical ring 343 has ribs
351 that extend towards the bottom portion 317 of the float assembly 305. The ribs 351
can be of the same material as the cylindrical ring 343.
Embodiment 4:
The fourth embodiment of the invention as described in Fig. 6 comprises any of the
previous embodiments wherein the cap assembly 311 further comprises an annular disc
371 such that:
1. the annular disc 371 is fixed to the casing 345;
2. the cylindrical ring 343 is below the annular disc 371;
3. the middle portion 315 of the float assembly 305 passes through the annular disc 371;
4. the top portion 313 of the float assembly 305 is above the annular disc 371.
The annular disc 371 can be constructed of porous acid resistant plastic, ceramic or any
other porous acid resistant material.
Embodiment 5:
The fifth embodiment of the invention as described in Fig. 7 comprises the cap assembly
311 of any of the previous embodiments wherein the top portion 343A of the cylindrical
ring 343 is shaped like a funnel.
Embodiment 6:
The sixth embodiment of the invention as described in schematic view in Fig. 8
comprises the cap assembly 311 wherein the transparent cap 301 comprises a top portion
301A and a bottom portion 301B such that the bottom portion 301B comprises a first
knife edge 361 substantially centered on the bottom portion 301B. The knife edge can be
constructed of the same material as the transparent cap 301.
Embodiment 7:
The seventh embodiment of the invention as described in schematic view in Fig. 9
comprises the cap assembly 311 of Embodiments 1 to Embodiment 6 wherein the upper
portion 313 of the float assembly 305 comprises a second knife edge 372 wherein the
second knife edge 372 is substantially centered on the upper portion 313.
Embodiment 8:
The eighth embodiment of the invention as described in Fig. 10A, Fig. 10B and Fig. 10C comprises either of the previous embodiments wherein the bottom portion 317 of the float assembly 305 is either a disc, a cylindrical or shaped like a cone respectively. Embodiment 9:
The ninth embodiment of the invention comprises a lead acid battery further comprising the cap assembly 311 of any of the previous embodiments.
It is reiterated that the above embodiments only by way of example and that the invention can be embodied in many other ways evident to a person skilled in the art.
The above embodiments are intended to only exemplify the various manners in which the invention can be embodied. The embodiments are not intended to limit the scope of the invention. The invention, as would be evident to a person skilled in the art, can be exemplified in many other ways.

We Claim:
1. A cap assembly 311 for a cell 31of a lead acid battery, such cell 31 comprising electrolyte 321, the cap assembly 311 comprising:
a. a transparent cap 301 comprising vent holes 303;
b. a float assembly 305 comprising an upper portion 313, middle
portion 315 and a bottom portion 317 such that:
1. the upper portion 313 of the float assembly 305 can be seen within the transparent cap 301;
2. the bottom portion 317 of the float assembly 305 is connected at one end to the middle portion 315.
c. a ring assembly 341 comprising a cylindrical ring 343 and a casing
345 such that:
1. the cylindrical ring 343 comprises a top portion 343A and a bottom portion 343B;
2. the casing 345 comprises an inside wall 347 and a protrusion 348A on the inside wall 347 such that the top portion 343A of the cylindrical ring 343 can rest on the protrusion 348A when the level of the electrolyte 321 is below a first predetermined level A;
d. the float assembly 305 is aligned such that:
1. the upper portion 313 of the float assembly 305 is above the cylindrical ring 343 and within the transparent cap 301;
2. the middle portion 315 of the float assembly 305 passes substantially through the cylindrical ring 343 and can move freely within the cylindrical ring 343;
3. the bottom portion 317 of the float assembly 305 is in contact with the electrolyte 321 such that when the level of the electrolyte 321 is above a second predetermined level B, the bottom portion 317 of the float assembly 305 comes in contact with the bottom portion 343B of the cylindrical ring 343.
2. The cap assembly 311 of claim 1 such that the transparent cap 301 has markings 322 on it.
3. The cap assembly 311 of any of the preceding claims wherein the top portion 343A of the cylindrical ring 343 has ribs 351 that extend towards the bottom portion 317 of the float assembly 305.
4. The cap assembly 311 of any of the preceding claims further comprising an annular disc 371 such that:

1. the annular disc 371 is fixed to the casing 345;
2. the cylindrical ring 343 is below the annular disc 371;
3. the middle portion 315 of the float assembly 305 passes through the annular disc 371;
4. the top portion 313 of the float assembly 305 is above the annular disc 371.

5. The annular disc 371 of claim 3 wherein the annular disc 371 comprises either ceramic or any other porous acid resistant material.
6. The cap assembly 311 of any of the preceding claims wherein the top portion 343A of the cylindrical ring 343 is shaped like a funnel.
7. The cap assembly 311 of any of the preceding claims wherein the transparent cap 301 comprises a top portion 301A and a bottom portion 301B such that the bottom portion 301B comprises a first knife edge 361 substantially centered on the bottom portion 301B.
8. The cap assembly 311 of any of claims 1 to claims 6 wherein the upper portion 313 of the float assembly 305 comprises a second knife edge 372 wherein the second knife edge 372 is substantially centered on the upper portion 313 of the float assembly 305.
9. The cap assembly of any of the preceding claims wherein the bottom portion 317 of the float assembly 305 is either a disc, a cylindrical or shaped like a cone.
10. A lead acid battery further comprising the cap assembly 311 of any of the previous claims.