An E-Battery is basically your energy provider taking your surplus and allowing you to consume it back for a small fee or for free, depending on the provider.
For simulation purposes it works like a 'big' battery storage, but because it's not a real battery (Lead Acid or Lithium) it does not need all to account for all the parameters like temperature, deep discharge, etc...
How can I define a 'universal' battery, I did not find this.