FIELD OF THE INVENTION
The present invention in general relates to a tubular lead-acid battery. More particularly,
the present invention relates to a tubular lead-acid battery with tubular negative plate to
5 increase battery life time.
BACKGROUND OF THE INVENTION
Lead acid batteries are commonly used inverter batteries as they provide a consistent
10 amount of current for an extended period of time. In general, Lead acid batteries are of two
types: flat plate batteries and tubular batteries.
In flat plate batteries, both positive and negative plates are made of grids of lead alloy. The
grids are made of transverse and longitudinal ribs, enclosed in a frame and a lug near the
15 top corner. These grids are pasted with a paste of active material and then the paste is
cured. The cured plate is then enveloped in a Polyethylene (PE) separator. During
charging and discharging process, the active material undergoes expansion and
contraction. After repeated charge-discharge cycles, the active material tends to get
loosened from the plate and swells and sheds. This swelling and shedding is somewhat
20 prevented by enveloping the plate in PE separator. PE separator thus has dual function. It
prevents shedding of active material and separates positive and negative plates to prevent
shorting.
Tubular technology was introduced for the construction of battery, to increase the battery
25 life, wherein the active material is sealed in polyester tubes called gauntlets, instead of
pasting it on the surface of the plate.
Tubular lead acid battery typically comprises of tubular positive plate and flat negative
electrode plates separated by micro-porous separators, with sulphuric acid serving as an
30 electrolyte. Figure 1 illustrates the structure of positive and negative plates of a traditional
tubular lead acid battery (100). The tubular positive plate (110) is made of spines of lead
3
alloy. One end of the spines is connected to a top bar having a lug. The other ends of the
spines are loose. These spines are inserted in a micro-porous, non-conductive hollow tube
(120), also known as gauntlet, of a polyester fiber. Inside each hollow tube, one spine is
inserted. The active material for the positive plate is in the form of a powder. After spines
5 are inserted in the gauntlet tubes, dry active powder is filled in the gauntlet tubes and then
the open end of the spines is sealed with a plastic bottom bar (130). The negative plate
(140) is in flat grid form.
Hence, to make it clear, flat plate batteries have both positive and negative plates in flat
10 grid form. Tubular batteries have only negative plate as flat pasted grid, while positive plate
is in the form of tubes.
When a flat plate battery discharges, the electrolyte dilutes and the lead sulphate deposits
on the lead plates. When the battery is recharged, the process reverses and the sulphate
15 dissolves into the electrolyte. During this charge-discharge process, the active material of
positive and negative plates expands and contracts. Therefore, flat plates have to be
enveloped in Polyethylene separator, because with consistent use, active material swells
and sheds, causing loss of capacity of the battery.
20 In tubular batteries, the tubular design of positive plate keeps the active material
mechanically together and presses it onto the gauntlet tube. Volume changes during
charge and discharge are mostly compensated by high elasticity of the gauntlet material.
While negative plates contain spongy metallic lead material within a rectangular grid
structure having a number of pockets. After a long time or after a number of charge25 discharge cycles, negative material swells and loses strength to hold on to the negative
grid.
Battery life ends due to cell short and no supporting material to react when the active
material of negative plate gets shedded and mixed with the electrolyte.
30
4
A number of solutions are proposed in the literature to solve the problem of swelling and
shedding of the negative active material and thereby increasing the battery life.
For example, the Chinese patent literature, CN103618067A, aims at providing a solution to
5 the above mentioned problems by disclosing a tubular negative plate of lead-carbon
battery. The negative plate disclosed in the patent literature comprises of a negative plate
grid and filled active substance powder. The negative plate grid is of a fence structure
consisting of transverse beams and conductive cores perpendicular to the transverse
beams. A sleeve layer is arranged outside the negative plate grid and the gap among the
10 sleeve layer and the conductive cores is filled with the active substance.
A utility model, CN202142609U, discloses a tubular lead-acid storage battery which aims
at reducing the weights of the grids and increasing the gravimetric specific energy of the
tubular lead-acid storage battery, while guaranteeing the performance of the positive and
15 negative tubular grids. The battery disclosed by the utility model comprises a positive plate
comprising a positive tubular grid which in turn comprises a positive plate lug, a currentcollecting bus and a round bar; a negative plate comprising a negative tubular grid which in
turn comprises a negative plate lug, a frame, a transverse inner rib and vertical inner rib; a
clap board and a battery shell. The round bar comprises a core rod made from high
20 polymer materials and a casing pipe made from lead alloy and the casing pipe is wrapped
outside the core rod.
As disclosed in the literature, negative plates are being constructed as grid structures,
which are eventually prone to swelling and shedding during charge-discharge cycles.
25
The present invention solves all the above mentioned problems in its own ways.
OBJECT OF THE INVENTION
30 It is therefore an object of the present invention to provide a tubular lead acid battery with
tubular negative plate having same construction as positive plate, so as to avoid blisters,
5
swelling and shedding of active material of negative plate and thereby increasing the
battery life.
SUMMARY OF THE INVENTION
5
The present invention provides a tubular lead acid battery with tubular negative plate.
In one aspect, the present invention provides a tubular lead acid battery which comprises a
tubular positive plate, a tubular negative plate, an electrolyte and a plastic frame wherein
10 each of the tubular positive and negative plate is made up of spine of lead alloy inserted
into a gauntlet tube. One end of the spine is connected to a top bar having a lug while
other ends of the spine are loose. The gauntlet tube consists of hollow tubes of a polyester
fibre and inside each of the hollow tube, one spine is inserted. Active material of each of
the positive and negative tubular plates is in the form of dry powder filled in the gauntlet
15 tubes and then the open ends of the spines are sealed with a plastic bottom bar. The
plastic frame holds and covers the top bar and bottom bar of positive and negative tubular
plates while rest of the plates remain exposed to each other.
The foregoing is a summary and thus contains, by necessity, simplifications,
20 generalizations and omissions of detail; consequently, those skilled in the art will
appreciate that the summary is illustrative only and is not intended to be in any way limiting
of the invention. As will also be apparent to one of skilled in the art, the operations
disclosed herein may be implemented in a number of ways, and such changes and
modifications may be made without departing from this invention and its broader aspects.
25 Other aspects, inventive features, and advantages of the present invention, as defined
solely by the claims, will become apparent in the non-limiting detailed description set forth
below.
BRIEF DESCRIPTION OF THE DRAWINGS
30
6
The above and other objects and features of the invention will become apparent from the
following description of preferred embodiments taken in conjunction with the accompanying
drawings, in which like reference numbers indicate like features.
5 Figure 1 illustrates the structure of positive and negative plates of a traditional tubular leadacid battery.
Figure 2 illustrates the tubular construction of negative plate of the tubular lead acid battery
according to an embodiment of the present invention.
10
DETAILED DESCRIPTION OF THE INVENTION
The embodiments of the present invention will now be described more fully with reference
to the accompanying drawings, in which some of the embodiments are shown. The
15 following description is intended to be illustrative of embodiments of the invention and
should not be taken to be limiting.
Figure 2 illustrates the tubular construction of negative plate of the tubular lead acid battery
according to an embodiment of the present invention. The tubular negative plate (200)
20 consists of spines (210) of lead alloy slipped into a porous tube (230) of a polyester fibre
which contains the active material (220) in free space between the spine (210) and the
braided tube (230) (also known as gauntlet). The spines (210) are centralized by means of
fins (240) integral with the spine (210) in the gauntlet (230). One end of the spine (210) is
connected to a top bar having a lug while other ends of the spine are loose. Active material
25 (220) is used as dry powder filled in the gauntlet tubes and then the open ends of the
spines (210) are sealed with a plastic bottom bar (250). Each annulus is filled with the
active material which makes intimate contact with the supporting spines. The active
material is tightly packed into the tube and when fully formed becomes solid but highly
porous making a perfect electrical contact with the spines which, in turn conduct the
30 current to the terminals. The electrolyte is allowed to penetrate freely, whilst the tubular
sleeve acts as an effective retainer of the active material.
7
Tubular positive plate is also of the same construction as the negative plate.
Since both the plates have gauntlets, it act as separators between positive and negative
5 plates. Hence, PE separators are not required. However, to maintain a small gap between
positive and negative plates, a plastic frame is used. The plastic frame holds and covers
the top bar and bottom bar of both positive and negative tubular plates. Rest part of plates
remain exposed to each other to react during charging and discharging.
10 In the tubular lead-acid battery of the present invention, the active materials are lead
dioxide (PbO2) in the positive plate, sponge lead (Pb) in the negative plate, and a solution
of sulphuric acid (H2SO4) in water as the electrolyte. The chemical reaction during
discharge and recharge is normally written:
15
According to the embodiment of the present invention, since the active material is
contained in gauntlet tubes and the gauntlet material is sufficiently elastic to accommodate
the expansion and contraction of active material during charging-discharging cycles, the
20 issue of plate swelling and shedding of active material does not arise. Consequently, the
life of the battery increases.
While the foregoing written description of the invention enables one of ordinary skills to
make and use what is considered presently to be the best mode thereof, those of ordinary
25 skill will understand and appreciate the existence of variations, combinations and
equivalents of the specific embodiment and details herein.
8
While the preferred embodiments of the invention have been described and illustrated, it
will be appreciated that various changes can be made therein without departing from the
scope of the invention.

We claim:

1. A tubular lead acid battery comprising:
a tubular positive plate;
5 a tubular negative plate (200);
an electrolyte; and
a plastic frame,
wherein each of the tubular positive and negative plate comprises a plurality of
spines (210) slipped into a plurality of gauntlets (230) containing active material
10 (220) in free space between the spine (210) and the gauntlet (230).
2. The tubular lead acid battery as claimed in claim 1, wherein the spines (210) are
centralized by means of fins (240) integral with the spine (210) in the gauntlet
(230).
15
3. The tubular lead acid battery as claimed in claim 1, wherein one end of the spine
(210) is connected to a top bar having a lug and the other ends are sealed with a
plastic bottom bar (250).
20 4. The tubular lead acid battery as claimed in claim 1, wherein the gauntlet (230) is a
hollow tube of a polyester fibre.
5. The tubular lead acid battery as claimed in claim 1, wherein a single spine (210) is
inserted inside each of the gauntlet (230).
25
6. The tubular lead acid battery as claimed in claim 1, wherein the gauntlets (230) are
separators between positive and negative plates.
7. The tubular lead acid battery as claimed in claim 1, wherein the active material
30 (220) is used as dry powder filled in the gauntlet (230).
10
8. The tubular lead acid battery as claimed in claim 1, wherein the plastic frame holds
and covers the top bar and bottom bar of positive and negative tubular plates, and
maintains a small gap between positive and negative plates.
5 9. The tubular lead acid battery as claimed in claim 1, wherein the active materials
(220) are lead dioxide (PbO2) in the positive plate, sponge lead (Pb) in the
negative plate, and the electrolyte is a solution of sulphuric acid (H2SO4) in water.
10. The tubular lead acid battery as claimed in claim 1, wherein the spines (210) are
10 made of lead alloy.