Patent ID: 8047241

Claim:
A method for filling a battery cell with electrolyte, wherein the battery cell is provided with an electrolyte injection receptacle, comprising the steps of: a) establishing a sealed connection between said electrolyte injection receptacle and a connection nozzle of a fill head defining a chamber connected through respective valves to a source of high pressure, to the free atmosphere and to a source of high vacuum, wherein only one of said valves can be open at any time, while during the present step a) said valve leading to the free atmosphere being open; b) opening said valve leading to said high vacuum for a predetermined first period to discharge air from the interior of said battery cell through said chamber; c) separating a major upper portion of the interior of said chamber from a lower portion thereof communicating with said connection nozzle by a sliding shut-off plunger and opening said valve connecting to the free atmosphere; d) dispensing a prescribed amount of electrolyte in said upper portion of said chamber through a temporarily opened electrolyte fill port so that the electrolyte fills a part of said interior above said shut-off plunger, while keeping said valve leading to the free atmosphere open; e) raising said shut-off plunger to let a major portion of said dispensed liquid be sucked into the interior of said battery cell under the effect of the vacuum established therein in step b) and allowing any gas bubble in said battery cell to get removed through the electrolyte; f) providing a mechanical support for said battery cell and opening said valve connected to said source of high pressure for a second predetermined period to push said electrolyte into said battery cell; g) opening said valve leading to the free atmosphere for a third predetermined period; and h) repeating steps f) and g) at least once for the more complete removal of gases from the battery cell and filling the prescribed volume of electrolyte; and i) disconnecting said battery cell from said fill head.