If you as a producer with an obligation to register do not have a branch in Germany, you can register yourself, or you can appoint an authorised agent situated in Germany (§ 2 paragraph 15a) to do so. This authorised agent takes on your obligations resulting from BattG in his own name and applies for the necessary registrations in your stead.
Any reliable and legally capable legal person with a branch in Germany can be an authorised agent. Only one authorised agent may be appointed for all brands and types of batteries from one producer.
By appointing an authorised agent all resulting obligations for a producer without a branch in Germany are transferred to the domestic authorised agent chosen by the producer.
A valid appointment of an authorised agent must be in writing and in German (§ 26 paragraph 2 clause 4 BattG). The contents of this appointment are not checked by stiftung ear, though, and the appointment of a BattG authorised agent does not require any confirmation by stiftung ear.
If the BattG authorised agent is no longer acting for you, the obligations return back to you and you must if necessary apply for the necessary registrations yourself.