It would be a nice feature to be able to have charged batteries right away, without requiring another system to charge them. In mods where electricity production can be complicated, batteries could become a sort of "early" source of electricity.
Considering that batteries require a block of redstone that is electrically "active", it even fits the logic of the game; and if it's an optional feature it shouldn't cause any problems.

Sorry for the late reply.
This is indeed a good idea and easily possible. I'll add this feature soon and release it for 1.19.2 and 1.20.1

The request was added and released with version 43.1.0 for 1.19.2 and 47.1.0 for 1.20.1