Method for welding a splice by means of an ultrasonic welding device , wherein the ultrasonic welding device has a sonotrode for generating ultrasonic vibrations, an anvil , a first lateral element , a second lateral element and a compaction chamber , the height (H) of which is adjustable by varying a distance between the sonotrode and the anvil and the width (B) of which is adjustable by varying a distance between the first lateral element and the second lateral element , wherein the method comprises: arranging first conductor portions of at least two electrical conductors to be welded in the compaction chamber ; adjusting the width (B) of the compaction chamber to a predetermined value for a first welding operation; performing the first welding operation by activating the sonotrode and compressing the first conductor portions between the sonotrode and the anvil , wherein the first conductor portions are welded together to form a first splice ; arranging a second conductor portion of at least one further electrical conductor to be welded and the first splice in the compaction chamber ; characterised by the following: adjusting the width (B) of the compaction chamber to a predetermined value for a second welding operation, wherein the width (B) of the compaction chamber for the second welding operation is greater by a predetermined tolerance value (ΔB) than the width (B) of the compaction chamber for the first welding operation; and performing the second welding operation by reactivating the sonotrode and compressing the first splice and the second conductor portion between the sonotrode and the anvil , wherein the first splice and the second conductor portion are welded together to form a second splice , wherein the predetermined tolerance value (ΔB) is at least 0.01 mm, and wherein the predetermined tolerance value (ΔB) is at most 5 mm. arranging first conductor portions of at least two electrical conductors to be welded in the compaction chamber ; adjusting the width (B) of the compaction chamber to a predetermined value for a first welding operation; performing the first welding operation by activating the sonotrode and compressing the first conductor portions between the sonotrode and the anvil , wherein the first conductor portions are welded together to form a first splice ; arranging a second conductor portion of at least one further electrical conductor to be welded and the first splice in the compaction chamber ; adjusting the width (B) of the compaction chamber to a predetermined value for a second welding operation, wherein the width (B) of the compaction chamber for the second welding operation is greater by a predetermined tolerance value (ΔB) than the width (B) of the compaction chamber for the first welding operation; and performing the second welding operation by reactivating the sonotrode and compressing the first splice and the second conductor portion between the sonotrode and the anvil , wherein the first splice and the second conductor portion are welded together to form a second splice , wherein the predetermined tolerance value (ΔB) is at least 0.01 mm, and wherein the predetermined tolerance value (ΔB) is at most 5 mm. <EOS>