Improvements in Electrical Accumulators.
Year: 1896

page_text: Date of Application, 20th June, 1896
Complete Specification Left, 22nd Mar., 1897-Accepted, 1st. May, 1897
PROVISIONAL SPECIFICATION.
Improvements in Electrical Accumulators.
We, FRANCIS WILLIAM GREENGRASS, Electrical Engineer, of Church Street,
Epsom, and STANLEY REYNOLDS DOCKING, Merchant, of Dingwall Road, Croydon,
both in the County of Surrey, do hereby declare the nature of this invention to be
as follows:-
The object of our invention is to provide an electrical accumulator especially
adapted for use in supplying current to the motors of horseless carriages and other
apparatus wherein lightness and storage capacity are of first importance."
In accumulators as usually heretofore constructed, owing to expansion due to
increase of the active material forming the plate, buckling of the plate has ensued,
and to remedy this the tendency of inventors and manufacturers has been in the
direction of stiffening the plate by increasing the bulk and stiffness of the lead
grids or frames which support or carry the active material, or by corrugating the
plate or otherwise rendering it more rigid, but all such attempts have not only
increased weight and bulk, but have not been successful.
According to our invention we make our plates as mobile as possible and of a
compressible character so as to permit the compression due to expansion to take
place naturally and within the limits of the plate itself; the result of this construc-
tion is that no buckling takes place, whereas with any system of stiffening such as
above referred to, should expansion affect in the least degree the uniform distance
apart and resistance between the plates, the consequent buckling though slow is
practically irresistible and finally destroys the plate.
In the manufacture of our improved plates and for the purpose stated we use
long continuous spirals of thin lead or lead alloy which may be easily produced
by the mechanical turning off a cylinder of the metal in an ordinary lathe or
otherwise. A sufficient quantity of these spiral strips for a plate is then combed.
out to form the plate and slightly flattened, care being taken that in the flattening
process the area produced is in suitable degree in excess of that of the finished plate.
The roughly formed plate is then pressed, and sufficiently but not too much con-
solidated. After removal it is trimmed to rectangular or required form, still
maintaining an area in excess of that of the finished plate. This margin is then
burnt down and forms a solid edging entirely round the plate.
A plate thus formed is exceedingly mobile, easily compressible, has an enormously
active surface, and is about one-tenth the weight of an ordinary plate of the same
capacity; it is entirely open in every part to the action of the electrolyte, and can be
electrically formed in about one-third of the ordinary time; owing also to the spiral
form of the shavings it retains the active material in a better manner, and as each
shaving composing the plate is a separate conductor leading to the consolidated edge
the plate has a minimum resistance, and owing to its compressible nature no strains
can be set up to produce buckling and short circuiting.
Such plates may be mounted in the following manner. The negatives are suitably
spaced apart, and an angular shaped lead clip is burnt upon the bottom corners acting.
as a conductor and also as feet adapted to stand upon the bottom of the containing
vessel. The outside plate of the series is consolidated at the top corner by burning
down the shavings and melting in a cast lead boss, into which is cast a coarse

page_text: threaded screw which passes through the ebonite (or other material) of the cell and
forms the negative terminal. Between the side of the vessel and the boss on the
negative plate a rubber washer is placed and by the screw tightly compressed; no
leakage taking place, there is no action of the acid upon the terminal. The entire
plates are submerged, and the terminal leaves the cell below the level of the
electrolyte.
The positive plates are mounted in a different manner, not standing (or being
packed) in the vessel, but suspended in the following manner upon blocks moulded
upon the interior of the containing vessel.
A lead tube is cast having one end closed by a solid boss, in which is embedded
a screw forming the positive terminal, and corresponds to the boss on the negative
plate.. Into, the end of the tube is inserted an insulated metal stiffening rod (the
insulation preventing local action by contact). The tube is then sealed up by
burning up the open end. The object is to obtain rigidity and reduce weight, and
any material possessing the qualities may be used. The tube is then burnt into the
top edges of the positive plates and the whole combination is entirely submerged in
the electrolyte.
The containing vessels are preferably moulded with an enlarged top, this enlarge-
ment starting from the level which the electrolyte takes when all the plates are
submerged, and forms a clean level rebate; the object of this is to get a flange
upon which a plate of glass or other suitable non-conducting material can be laid
(with or without an elastic edging), and just pressing by its superior weight upon the
surface of the electrolyte. This arrangement allows of the free escape of gas during
charging, and the plate being held down by atmospheric pressure and its weight during
discharge, permits the whole cell to be swung freely from side to side without per-
ceptible motion of the electrolyte; there is no wave action, and the energetic and
destructive washing action on the plates is entirely obviated, and the life of the plates
indefinitely prolonged.
Upon each inner end of the vessel are moulded projections having a depression in
the centre, and in these rest the ends of the suspenders, connecting the positive plates
already described. This arrangement of parts is such that it permits a partial valve-
like sealing of the cell, and the submersion of all connections destroys the tendency to
electrical leakage taking place by discharging itself across the moist top cover from
terminal to terminal; also reduces useless weight and minimises the quantity of the
electrolyte. Any number of plates may be mounted in the same manner in one
containing vessel and electrically connected.
The plates are electrically formed on the Planté system and can also be adapted to
the pasted method. When the latter process is adopted, the plate is placed in a mould,
the paste being spread thickly upon the surface. A pressure block then presses the
paste completely through the plate. To prevent a too consolidated plate, stops are
inserted as already explained.
CT 1800
J. C. CHAPMAN,
Agent.
COMPLETE SPECIFICATION.
Improvements in Electrical Accumulators.
We,. FRANCIS WILLIAM GREENGRASS, Electrical Engineer, of Church Street,
Epsom and STANLEY REYNOLDS DOCKING, Merchant, of Dingwall Road, Croydon, both
in the County of Surrey, do hereby declare the nature of this invention and in what
manner the same is to be performed to be particularly described and ascertained in
and by the following statement :-
The object of our invention is to provide an electrical accumulator especially adapted

page_text: .
for. use in supplying current to the motors of horseless carriages and other apparatus
wherein lightness and storage capacity are of first importance.
In accumulators as usually constructed heretofore, owing to expansion due to
increase of the active material forming the plate, buckling of the plate has ensued, and
to remedy this the tendency of inventors and manufacturers has been in the direction
of stiffening the plate by increasing the bulk and stiffness of the grids or frames which
support or carry the active material, or by corrugating the plate or otherwise to render
it more rigid; all such attempts however, have not only increased the weight and bulk
but have not been successful.
According to our invention we make our plates as mobile as possible and of a
compressible character so as to permit the compression due to expansion to take place
within the plate itself; the result of this construction is that there is no buckling,
whereas with plates as heretofore constructed should the uniform distance apart and
resistance between the plates be affected in the least degree by the expansion, the
consequent buckling though slow is practically irresistible and finally destroys the plate.
In order that our invention may be fully understood we will describe same with
reference to the accompanying drawings of which Fig. 1 is a sectional side elevation
of the accumulator, Fig. 2 is a plan of the same,
Fig. 3 is a sectional elevation of the accumulator and Fig. 4 is a vertical section
thereof on the line 1-2 of Fig. 1.
The same letters of reference refer to the same parts in the several figures.
In the manufacture of our improved plates and for the purpose stated we use long
continuous spirals of load or lead alloy which may easily be produced by mechanically
turning them from a cylinder of the metal in an ordinary lathe or otherwise as will be
readily understood. A sufficient number of these spirals to form a plate is then
combed out and as it were tangled together or intermeshed. The arrangement of the
lay of the spirals is approximately horizontal as indicated in Fig. 1 so as to lie
approximately at right angles to the vertical separators S S which are placed between
the plates in the cell. The object of this disposition of the separate spirals is to
prevent lateral bulging of the plates when in use and it also enables the plates to keep
free from the choking action of the active material formed, better for example, than
is the case with loosely wound ribbons or corrugated or embossed strips. The mass
of entangled spirals is then slightly flattened, care being taken that in the flattening
process the area of plate produced is in suitable degree in excess of that of the finished
plate. This roughly formed plate is then pressed and sufficiently but not too much
consolidated, its thickness being determined by stops placed in the mould. After
removal from the press it is trimmed to rectangular or required shape still maintaining
an area in excess of that of the finished plate. This excess marginal area is then
burnt or melted down and forms a solid edging as at a entirely round the plate,
depressions a¹ being formed in the upper edge for a purpose hereinafter explained.
The plates are finished, mounted and arranged in the following way and as illustrated
in the drawings in which 3 plates only are shown. Upon each lower corner of the
negative plates N N angular-shaped lead clips n n are burnt which serve as conductors
and also as feet adapted to rest upon the bottom of the containing vessel C thus
providing also a suitable clearance space c below the plates for deposits. The outside
plate N of the series is consolidated at the top corner B by burning down the spirals
and melting-in a cast lead boss 6 which is provided with a coarse threaded screw T
passing through the ebonite (or other material) of the cell and forming the negative
terminal. Between the side of the vessel C and the said boss b a rubber washer R is
interposed and by the screw T tightly compressed, so that no leakage takes place, and
there is no action of the acid on the terminal. The entire plates are submerged, and
the terminal leaves the cell C below the level of the electrolyte.
The positive plates P are mounted in a different manner, not standing or being
packed, in the vessel C, but suspended upon tubes L supported by lugs C₁ moulded
upon the interior of the containing vessel, and passing across the depressions a' in the
negative plates. The tubes L are of lead or the like and have one end closed to form

page_text: a solid boss, into which is fixed a screw T forming the positive terminal, and
corresponding to the screw T in the boss 6 on the negative plate N above referred to;
a rubber washer R¹ is also here interposed between plate and cell. Within each
tube L is placed an insulated stiffening rod L' of iron or any suitable material (the
insulation preventing local action by contact) and the tube is then sealed up by
burning up the open end. The object of thus forming the suspending pieces of the
positive plate is to obtain rigidity and lightness and any material possessing
the qualities may be used. The tube L is then burnt into the top edges of the
positive plate P and the whole combination entirely submerged in the electrolyte.
Plates thus constructed are exceedingly, mobile and can be "formed" electrically
in about one third of the ordinary time; owing also to the spiral form of the
elemental strips or shavings, the plate retains the active material in a better
manner and as each shaving composing the plate is a separate conductor leading
to the consolidated edge a, the plate has a minimum resistance, owing also to its
yielding nature no strains can be set up to produce buckling and short-circuiting.
When a plate of the ordinary kind is new, the interstices formed by the embossing
or corrugations allow of the free circulation of the electrolyte for a time, but upon
increasing formation of the active material from the plate the said interstices become
choked to the said electrolyte. With the mobile and open kind of plate formed by
the tangled spirals above referred to there is less tendency for the interstices to
become choked, and after a time the plate becomes practically a mass of porous
lead.
The containing vessels are preferably made with an enlarged top, this enlargement
starting from the level of the upper surface of the electrolyte when the plates and
their connections are immersed as described and form a level rebate r; the object
of this is to obtain a seat upon which a plate of glass or other suitable non-conducting
material G can be laid (with or without an elastic edging) so that its underside is
in contact with the surface of the electrolyte. This arrangement allows the free
escape of
gas during charging and the plate, held down by atmospheric pressure and
its weight during discharge, permits the whole cell to be swung freely from side to
side without perceptible motion of the electrolyte; there is no wave action, and the
energetic and destructive washing action on the plates is entirely obviated aud
the life of the plate considerably prolonged.
Upon each side of the vessel C are the bearers or lugs C' having a depression in
the centre, and in these rest the ends of the suspenders L, for supporting the
positive plates as already described. This arrangement of parts is such that it
permits a partial valve-like sealing of the cell, and the submersion of all connections
destroys the tendency to electrical leakage by discharge across the moist top cover
from terminal to terminal; it also reduces useless weight and minimises the quantity
of the electrolyte required. Any number of plates may be mounted in the same
manner in one containing vessel and electrically connected.
The plates are electrically "formed" preferably on the Planté system but they may
equally well be adapted to the pasted method. When the latter process is adopted,
the plate is placed in a mould, the paste, thin like ordinary paint, being spread thickly
upon the surface. A pressure block then presses the paste completely through the
plate. To prevent a too consolidated plate, stops are inserted in the mould as already
explained.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is:-
1. The manufacture of plates for electrical accumulators composed of entangled
spirals of lead or lead alloy gently compressed and arranged as specified and having
the margins consolidated by melting or burning so as to form a solid edging all round
the plate, substantially as and for the purposes herein set forth.
2. In an electrical accumulator having plates constructed as above described

page_text: supporting the negative plates in the cell on lead feet burned upon their bottom
corners and suspending the positive plate or plates on tubular rods supported by lugs
within the vessel the electrical connections being made and disposed substantially in
the manner set forth.
3. For use in an electrical accumulator such as above referred to a containing
vessel having a horizontal rebate at the level of the electrolyte adapted to receive
a sealing plate, the plates and their connections being entirely submerged beneath
said sealing plate in the electrolyte substantially as and for the purposes herein
described.
4. The herein described means for suspending the positive plates of an electrical
accumulator consisting of the lead tubes L constructed and arranged substantially
as and for the purposes stated.
5. An electrical accumulator having its containing vessel, plates and connections
constructed formed and adapted for use substantially in the manner herein described
and illustrated in the accompanying drawings.