IMPROVEMENTS IN APPARATUS FOR USE IN CHARGING SECONDARY BATTERIES OR ACCUMULATORS."
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by Thomas John Jones and Ernest
Cecil Rimington at the Office of the Commissioners of Patents on the 14th
September 1883.
THOMAS JOHN JONES of Princes Street, Hanover Square in the County of
Middlesex, Electrician and ERNEST CECIL RIMINGTON of Norwood in the County of
Surrey, Electrician, IMPROVEMENTS IN APPARATUS FOR USE IN CHARGING
SECONDARY BATTERIES OR ACCUMULATORS."
46
It frequently happens in charging secondary batteries or accumulators with a
series dynamo machine that in consequence of any slight diminutions in the speed
of the engine or other causes, the electromotive force of the dynamo machine
becomes less than the back or opposing electromotive force of the accumulators to
be charged, and when this happens the accumulators reverse the polarity of the
dynamo and discharge through it with a very large current, tending to make the
dynamo a motor, which would rotate in the reverse direction to the machine as
driven by the engine, thus causing
1* Great and destructive beating effect in the coils of the dynamo by reason of
the large current passing through it. -
2nd Great loss of power by reason of the accumulators discharging
3rd Great strain on the belting, shafting and engine &°
These aforesaid inconveniences usually necessitate constant care on the part of
an attendant to break the circuit as soon as the current reverses.
The object of the present invention is to entirely obviate these inconveniences
by means of an electro-mechanical contrivance, which, when the current falls
below a certain point prior to reversal, automatically cuts off the batteries from
the dynamo and substitutes for them a suitable resistance, through which the
dynamo is circuited until it recovers sufficient electromotive force to again
overcome the opposing electromotive force of the accumulators, and continue the
charging when the current is again automatically switched on to the batteries, thus
obviating any need of attention.
This contrivance consists essentially of a balance beam in the circuit of the
dynamo, in combination with an electro-magnet and mercury contacts arranged in
such manner that when the beam is oscillated in one direction the circuit is made
Dmine 77

page_text: through the batteries, and when oscillated in the other direction this circuit is
broken and is made through the resistance, the electro magnet being in the dynamo
circuit, and causing the beam to assume the former position, as soon as there is
sufficient current set up to excite the field magnets of the dynamo to such an
extent as to give a sufficient electro-motive force. The electro-magnet then
becomes strong enough to oscillate the beam which is adjustably weighted so as to
automatically assume the latter position when the electro-magnet loses its power.
The beam can be.so adjusted as not to be oscillated until the desired current is
obtained and the beam is provided with an adjustable bob for varying its sensibility
as required..
•
The surfaces of the mercury are so arranged that contact is made at the one
before it is broken at the other, and the surfaces are covered with some (preferably
non-oxidisable) fluid to prevent excessive sparking